The Flat Earth Society
Flat Earth Discussion Boards => Flat Earth Q&A => Topic started by: CommonCents on July 17, 2007, 08:40:03 AM
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I've heard it said before that photons don't break relativity because they are 'emitted' at light speed and don't accelerate to it. If this is the case, why can't a different particle be 'emitted' at greater than light speeds?
Let the flaming begin!!
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I've heard it said before that photons don't break relativity because they are 'emitted' at light speed and don't accelerate to it. If this is the case, why can't a different particle be 'emitted' at greater than light speeds?
Let the flaming begin!!
There are particles, generalized as tachyons, that are emitted during radioactive decay that go faster than the speed of light. Interestingly, these particles take more energy to slow to the speed of light. So c is actually some sort of asymptotic energy barrier. It's really interesting stuff.
Additionally, c is a constant based off of early vacuum experiments. You can alter vacuums to speed up c, like in a casimir vacuum.
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As long as I am hijacking your thread.
Photons are not traveling at c because they are emitted at that speed. This has been shown by cooling a photon, which slows it, then warming it, which speeds it back up to c. If it can only attain a velocity of c during its initial emition, these types of experiments could never work.
Typically, physicists will look at photons as waves for your thought argument. This allows them to ignore their mass. They will then look at them as particles when they need them to have mass. Basically we have the newtonian vs quantum laws that we pick and choose from. This is evidence that we have a flaw in our model at a more elementary level.
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It's not that they are emitted at c so they aren't traveling at c, it's that they are emitted at c so they don't accelerate to c.
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It's not that they are emitted at c so they aren't traveling at c, it's that they are emitted at c so they don't accelerate to c.
I understand. But then if you slow them down, how can they ever get back to c?
My point is they can because they are "massless."
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Perhaps they don't get back up to c. Perhaps they accelerate back up to near c. Are the experiments you mention being done in vacuums?
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In GR, I can't imagine anything being transmitted FTL. Although there is the group velocity aspect in which they travel FTL.
Other than GR though, superposition could be taken into account.
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In GR, I can't imagine anything being transmitted FTL. Although there is the group velocity aspect in which they travel FTL.
Other than GR though, superposition could be taken into account.
GR specifically states that massy objects cannot reach c, however there is no restriction in any of its laws against massy objects moving faster than c. This supposes that they begin and always remain faster than c.
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Perhaps they don't get back up to c. Perhaps they accelerate back up to near c. Are the experiments you mention being done in vacuums?
yes.
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General Relativity does not prohibit the movement of particles at velocities greater than c. It's just that objects with mass can't accelerate to c. Now, it is theorized, that tachyons exist and that they travel at FTL speeds. However, we can't see them until they have passed us by, otherwise, they would violate the no communication theorem. They also don't violate causality as a person observing them would see two of them, one coming and one leaving, and would have no way of differentiating which one is the real tachyon, thus, losing the message in the background noise.
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Thank you TheEngineer! So communication at FTL speeds is impossible according to GR? This is why a graviton that could be emitted at FTL speeds could not be the messenger particle for the force of 'gravity'?
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Yes, information transfer at FTL speeds is strictly prohibited by GR. Things can move at FTL speeds, but they can't tell us they are doing so. This would cause all kinds of problems with causality, so there is usually a very neat mathematical solution as to why information can't be transfered at FTL speeds. Such as a tachyon detector: It would be able to detect the incoming tachyon, but it would also emit an exact copy of that tachyon, thus losing the information.
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Yes, information transfer at FTL speeds is strictly prohibited by GR. Things can move at FTL speeds, but they can't tell us they are doing so. This would cause all kinds of problems with causality, so there is usually a very neat mathematical solution as to why information can't be transfered at FTL speeds. Such as a tachyon detector: It would be able to detect the incoming tachyon, but it would also emit an exact copy of that tachyon, thus losing the information.
That's not strictly correct. The "No-Communications" says we, not nature, cannot communicate at FTL speeds. Nature could, and probably does, communicate at FTL speeds.
From Wikipedia (http://en.wikipedia.org/wiki/No-communication_theorem)
In quantum information theory, a no-communication theorem is a result which gives conditions under which instantaneous transfer of information between two
observers is impossible.[/list]
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Oh, good Lord, here we go again. ::)
You must have a very narrow definition of an observer.
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Oh, good Lord, here we go again. ::)
You must have a very narrow definition of an observer.
Oh, it's much wider than your definition of local--That's for sure!
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Way to back up your argument, TomG.
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My definition of local in the context that it was used in that thread was less than global. One satellite could not give global, 24/7 coverage as I was led to believe.
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Way to back up your argument, TomG.
Still waiting on your reference for that Einstein quote you claim. You sure seem to be taking your time. Maybe you're lying?
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I guess I'm a little hesitant to agree with TomG...
Doesn't gravity work at FTL speeds? If I had an instrument that were unbelievable sensitive to changes in gravity... Couldn't we communicate, lightyears apart, by simply waving our arms around?
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Ah, look at that! TomG has made a statement he can't back up! He now tries to change the subject in true TomG fashion. It's getting harder and harder to tell the difference between the two Toms!
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Doesn't gravity work at FTL speeds? If I had an instrument that were unbelievable sensitive to changes in gravity... Couldn't we communicate, lightyears apart, by simply waving our arms around?
No, 'gravity' is subluminal.
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Ah, look at that! TomG has made a statement he can't back up! He now tries to change the subject in true TomG fashion. It's getting harder and harder to tell the difference between the two Toms!
1) I challenged you to back up your quote before your post; and 2) Your post doesn't ask for anything or reference the claim you're looking me to support.
We're still waiting on that reference...
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Ah, look at that! TomG has made a statement he can't back up! He now tries to change the subject in true TomG fashion. It's getting harder and harder to tell the difference between the two Toms!
1) I challenged you to back up your quote before your post;
Try keeping the threads straight, TomG.
2) Your post doesn't ask for anything or reference the claim you're looking me to support.
Those word games sure are cute. Too bad you used to cry about others using them. But I guess when you talk out your ass, you have to try to do something to divert our attention...
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Ah, look at that! TomG has made a statement he can't back up! He now tries to change the subject in true TomG fashion. It's getting harder and harder to tell the difference between the two Toms!
1) I challenged you to back up your quote before your post;
Try keeping the threads straight, TomG.
2) Your post doesn't ask for anything or reference the claim you're looking me to support.
Those word games sure are cute. Too bad you used to cry about others using them. But I guess when you talk out your ass, you have to try to do something to divert our attention...
1) Time is not that relative. You first, pal.
2) Since you're too lazy to ask for what you want and too pompous to provide references for your own quotes, don't be amazed when you don't get what you want as soon as you ask for it. All of life is not a government handout.
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Doesn't gravity work at FTL speeds? If I had an instrument that were unbelievable sensitive to changes in gravity... Couldn't we communicate, lightyears apart, by simply waving our arms around?
No, 'gravity' is subluminal.
Ah, thanks.
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Doesn't gravity work at FTL speeds? If I had an instrument that were unbelievable sensitive to changes in gravity... Couldn't we communicate, lightyears apart, by simply waving our arms around?
No, 'gravity' is subluminal.
Evidence? I thought 'gravity', in theory, traveled at, not below, the speed of light.
From Wikipedia (http://en.wikipedia.org/wiki/Speed_of_gravity)
In mathematical physics, particularly in the context of classical theories of gravitation, the speed of gravity refers to the speed at which gravitational field propagates. This is the speed at which changes in the distribution of energy and momentum result in noticeable changes in the gravitational field which they produce.
Where no other theory is specified, discussion of the speed of gravity is normally in reference to general relativity, which predicts it to equal c.
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I believe TheEngineer has already stated that gravitation travels in waves near c. Anyway here's an article about that very subject for your enjoyment.
http://www.physorg.com/news103902795.html
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I believe TheEngineer has already stated that gravitation travels in waves near c. Anyway here's an article about that very subject for your enjoyment.
http://www.physorg.com/news103902795.html
He's stated it both ways, at c and "subluminal" (below c). I think he just erred with "subluminal" in this thread. I've already posted experimental evidence that gravity travels at c in another thread.
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How do you know it travels AT the speed of light and not JUST UNDER the speed of light or something >_<
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How do you know it travels AT the speed of light and not JUST UNDER the speed of light or something >_<
I don't know. I do believe that GR is clear in its prediction that gravity travels at exactly c. I accept GR as the best theory for determining such speeds. I also put confidence in the experimental evidence that puts a reasonable confidence level about the speed of gravity that allows only a small probability that it could be "subluminal".
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My previous post was, and I hope was interpreted as, a joke.
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I also put confidence in the experimental evidence that puts a reasonable confidence level about the speed of gravity that allows only a small probability that it could be "subluminal".
While I did somewhat misspeak, gravity is assumed to propagate at c in GR. In the first experimental measurement of the speed of gravity, it was calculated to be .95c, however, there was a rather large experimental error of .25c, so the speed of gravity could very well be c, which I am inclined to agree with.
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I also put confidence in the experimental evidence that puts a reasonable confidence level about the speed of gravity that allows only a small probability that it could be "subluminal".
While I did somewhat misspeak, gravity is assumed to propagate at c in GR. In the first experimental measurement of the speed of gravity, it was calculated to be .95c, however, there was a rather large experimental error of .25c, so the speed of gravity could very well be c, which I am inclined to agree with.
I thank you for clarifying.
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That's not strictly correct. The "No-Communications" says we, not nature, cannot communicate at FTL speeds. Nature could, and probably does, communicate at FTL speeds.
From Wikipedia (http://en.wikipedia.org/wiki/No-communication_theorem)
In quantum information theory, a no-communication theorem is a result which gives conditions under which instantaneous transfer of information between two
observers is impossible.[/list]
Back up your statement that nature can communicate at FTL speeds, but we can't. And please, please misuse Bell's work again. Please.
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That's not strictly correct. The "No-Communications" says we, not nature, cannot communicate at FTL speeds. Nature could, and probably does, communicate at FTL speeds.
From Wikipedia (http://en.wikipedia.org/wiki/No-communication_theorem)
In quantum information theory, a no-communication theorem is a result which gives conditions under which instantaneous transfer of information between two
observers is impossible.[/list]
Back up your statement that nature can communicate at FTL speeds, but we can't. And please, please misuse Bell's work again. Please.
Ah, now I understand. You just can't read. That's alright. We forgive you.
Nowhere in that quote do I state that nature can communicate at FTL speeds. Nice straw man though. divito must be proud of you.
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That's not strictly correct. The "No-Communications" says we, not nature, cannot communicate at FTL speeds. Nature could, and probably does, communicate at FTL speeds.
Back it up.
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That's not strictly correct. The "No-Communications" says we, not nature, cannot communicate at FTL speeds. Nature could, and probably does, communicate at FTL speeds.
Back it up.
Since you asked so nicely and finally demonstrated that you can read, though only after prompting, I'm happy to support my assertion: physicist.org (http://www.physicist.org/pnu/1998/split/pnu399-1.htm)
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NONLOCALITY GETS MORE REAL. "Bell's Inequalities," the set of mathematical relations that would rule out the notion that distant quantum particles exert influences on each other at seemingly instantaneous rates, have now been violated over record large distances, with record high certainty, and with the elimination of an important loophole in three recent experiments, further solidifying the notion of "spooky action at a distance" in quantum particles. At the Optical Society of America meeting in Baltimore earlier this month, Paul Kwiat ([email protected]) of Los Alamos and his colleagues announced that they produced an ultrabright source of photon pairs for Bell's inequality experiments; they went on to verify the violation of Bell's inequalities to a record degree of certainty (preprint at p23.lanl.gov/agw/2crystal.pdf). Splitting a single photon of well-defined energy into a pair of photons with initially undefined energies, and sending each photon through a fiber-optic network to detectors 10 km apart, researchers in Switzerland (Wolfgang Tittel, Univ. Geneva, [email protected]) showed that determining the energy for one photon by measuring it had instantaneously determined the energy of its neighbor 10 km away--a record set by the researchers last year but now demonstrated in an improved version of the original experiment. (Tittel et al., Physical Review Letters, 26 October 1998.) A University of Innsbruck group performed Bell measurements with detectors that randomly switched between settings rapidly enough to eliminate the "locality loophole," which posited that one detector might somehow send a signal to the other detector at light or sub-light speeds to affect its reading. (Weihs et al.,Phys. Rev. Lett., website at http://www.uibk.ac.at/c/c7/c704/qo/photon/_bellexp/)
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Again, it's nature, not observers, that communicates FTL.
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So when did nature not become an observer?
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So when did nature not become an observer?
Always been that way. Check out QP, for example.
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We must be traveling at FTL speeds, as we've had this same argument before, so we must have violated causality.
Some recent popularizers of Bell's work when confronted with [Bell's inequality] have gone on to claim that telepathy is verified or the mystical notion that all parts of the universe are instantaneously interconnected is vindicated. Others assert that this implies communication faster than the speed of light. That is rubbish; the quantum theory and Bell's inequality imply nothing of this kind. Individuals who make such claims have substituted a wish-fulfilling fantasy for understanding. If we closely examine Bell's experiment we will see a bit of sleight of hand by the God that plays dice which rules out actual nonlocal influences. Just as we think we have captured a really weird beast--like acausal influences--it slips out of our grasp. The slippery property of quantum reality is again manifested.
Did you forget about the no communication theorem?
Or the fact that we were talking about GR?
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We must be traveling at FTL speeds, as we've had this same argument before, so we must have violated causality.
Some recent popularizers of Bell's work when confronted with [Bell's inequality] have gone on to claim that telepathy is verified or the mystical notion that all parts of the universe are instantaneously interconnected is vindicated. Others assert that this implies communication faster than the speed of light. That is rubbish; the quantum theory and Bell's inequality imply nothing of this kind. Individuals who make such claims have substituted a wish-fulfilling fantasy for understanding. If we closely examine Bell's experiment we will see a bit of sleight of hand by the God that plays dice which rules out actual nonlocal influences. Just as we think we have captured a really weird beast--like acausal influences--it slips out of our grasp. The slippery property of quantum reality is again manifested.
Did you forget about the no communication theorem?
Or the fact that we were talking about GR?
Nope. You're just confused in your thinking that nature is an observer and thereby constrained by the no-communications theorem. It's a common mistake.
Oh, and you really should put a date on your Pagels quote. He was great, but QP has moved on. Try to find a quote to support your belief from anytime after the October 26, 1998 AIP web reference or the associated APL article.
Oh, and I'm perfectly happy to demonstrate again to you the error of your ways. Don't hesitate to ask for help on anything you don't understand, such as nature not being an observer.
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Observations on entangled states naively appear to conflict with the property of relativity that information cannot be transferred faster than the speed of light. Although two entangled systems appear to interact across large spatial separations, no useful information can be transmitted in this way, so causality cannot be violated through entanglement. This is the statement of no communication theorem.
Although no information can be transmitted through entanglement alone, it is possible to transmit information using a set of entangled states used in conjunction with a classical information channel. This process is known as quantum teleportation. Despite its name, quantum teleportation cannot be used to transmit information faster than light, because a classical information channel is required.
Now, like I said, did you forget what we were talking about?
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Observations on entangled states naively appear to conflict with the property of relativity that information cannot be transferred faster than the speed of light. Although two entangled systems appear to interact across large spatial separations, no useful information can be transmitted in this way, so causality cannot be violated through entanglement. This is the statement of no communication theorem.
Although no information can be transmitted through entanglement alone, it is possible to transmit information using a set of entangled states used in conjunction with a classical information channel. This process is known as quantum teleportation. Despite its name, quantum teleportation cannot be used to transmit information faster than light, because a classical information channel is required.
Now, like I said, did you forget what we were talking about?
I haven't forgotten. Thanks for adding that copy-and-paste to the thread.
No useful information can be transmitted FTL. We can't create a causality violation. Did you think that I thought otherwise? Oh, and please ratchet up the quality of your references. Wikipedia just pales so much against APL, don't you think? Don't forget "after 1998" this time.
Oh, and while you're out there on the Internet searching, keep an eye out for your quote of Einstein: "gravity as a force does not exist".
Oh, and don't forget to let us know how Wikipedia should be updated with your single FoR that explains how two people are held down on the surface of the Earth, on opposite sides of the Earth, without portraying gravity as a force. We really need to get your insights into GR out there in Wikipedia, for the public good!
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Oh, just to help you out on understanding non-locality , here's a nice straightforward article:
Spooky Action at a Distance (http://eeng.net/CS/blogs/smileycoyote/archive/2007/07/04/516.aspx)
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I guess I'm a little hesitant to agree with TomG...
Doesn't gravity work at FTL speeds? If I had an instrument that were unbelievable sensitive to changes in gravity... Couldn't we communicate, lightyears apart, by simply waving our arms around?
That really depends on if gravitational waves really do exist. If they do exist then(Which I believe they do) then no because gravity can only travel at c however if they do not exist then that would mean that Newton was right and we could communicate across the universe in an instant. Too bad according to FE we can not prove they exist.
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No useful information can be transmitted FTL.
Oh, good Lord... ::) Did you just realize how stupid you made yourself seem so you had to quickly 'change' what you were talking about?
Oh, and please ratchet up the quality of your references. Wikipedia just pales so much against APL, don't you think?
No.
Oh, and while you're out there on the Internet searching, keep an eye out for your quote of Einstein: "gravity as a force does not exist".
In general relativity, the effects of gravitation are ascribed to spacetime curvature instead of to a force.
I'm pretty sure Einstein would not have thought differently, as it's his theory. ::)
Oh, and don't forget to let us know how Wikipedia should be updated with your single FoR that explains how two people are held down on the surface of the Earth, on opposite sides of the Earth, without portraying gravity as a force.
Geodesics as in, the things that cause gravitation, in GR, which you seem to agree with only every once in a while.
Oh, just to help you out on understanding non-locality
You are the one that needs the help in understanding it.
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No useful information can be transmitted FTL.
Oh, good Lord... ::) Did you just realize how stupid you made yourself seem so you had to quickly 'change' what you were talking about?
Oh, and please ratchet up the quality of your references. Wikipedia just pales so much against APL, don't you think?
No.
Oh, and while you're out there on the Internet searching, keep an eye out for your quote of Einstein: "gravity as a force does not exist".
In general relativity, the effects of gravitation are ascribed to spacetime curvature instead of to a force.
I'm pretty sure Einstein would not have thought differently, as it's his theory. ::)
Oh, and don't forget to let us know how Wikipedia should be updated with your single FoR that explains how two people are held down on the surface of the Earth, on opposite sides of the Earth, without portraying gravity as a force.
Geodesics as in, the things that cause gravitation, in GR, which you seem to agree with only every once in a while.
Oh, just to help you out on understanding non-locality
You are the one that needs the help in understanding it.
Evading every question I see. How sad. You have the articles. You have the text. You have been pointed to your misunderstanding that Nature is not an observer. You have in hand, text from AIP, the link to the APL article, the relevant Wikipedia entry, and the "simple" article on eeng all showing that that Nature probably transmits information FTL.
You've failed for hours now to produce the quote you ascribed to Einstein, "Gravity as a force does not exist." Relying on Wikipedia's short summary, and ignoring the more detailed text, to justify your quote. Even Wikipedia disagrees with you.
You've failed to produce a single FoR that does not need to portray gravity as a force in order to explain how two people standing on opposite sides of the Earth remain on Earth. Even Wikipedia disagrees with you. You evade the challenge with your standard "Horses and the feathers they don't have" reply. We see through your pompous attitude, especially when you can't deliver.
You failed to find a reference that supports your claim that Nature cannot transmit information FTL, beyond something before 1988.
You make the outlandish statement that a top-shelf peer-reviewed reference is inferior to Wikipedia. That's really lame.
I guess we're just seeing you run for cover when you have to face that you're wrong.
Oh, and I have never maintain that useful, as in useful to the observers, information can be transferred FTL. You on the other hand have claimed that Nature cannot do so by misapplying No-Communications Theory, failing to understand that Nature is not an observer.
Oh, and one more thing, I hope you finally used the search feature that you're so pompous about referring others to and found the reason why FE doesn't support GR and how GR doesn't support FE. Let me know if you need help using it.
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No useful information can be transmitted FTL.
Nice change.
"Many things such as shadows can go FTL but not in a useful way which can carry information."
"It has long been known theoretically that it is possible for the "group velocity" of light to exceed c ... However, it is not possible to use this technique to transfer information faster than c"
As for Einstein actually saying that, I believe TheEngineer was more so paraphrasing Einstein's findings, that are available in many places.
"It occurred to Einstein – thinking first of all in visual terms, as was usual for him – that if a man were falling from the roof of his house and tried to let anything drop, it would only move alongside him, thus indicating the equivalence of acceleration and gravity. In Einstein's words, "the acceleration of free fall with respect to the material is therefore a mighty argument that the postulate of relativity is to be extended to coordinate systems that move nonuniformly relative to one another . . . .""
- http://www.aip.org/history/einstein/essay-einsteins-third-paradise.htm
"Einstein said that gravity is a function of mass alright but not as a force exerted by the mass! To the scientists of his day these words amounted to scientific heresy. If gravity is not a force, they asked, then what is it? Einstein's answer is no less than life changing! Gravity, he said, is the result of the mass of an object bending space! Bending Space! Can you imagine? I cannot!
What Einstein was saying is that objects do not fall because of an attractive force reaching out of an object and pulling it to itself, as Newton said."
"Einstein revolutionized modern science by putting forward the theory that gravity is not a force like other forces, but is a result of the fact that space-time is not flat."
"About 50 years ago, Albert Einstein gave us a revolutionary explanation for the gravity we are familiar with. Einstein said gravity is not a force of attraction, as Isaac Newton described it, but rather, comes from the warping of space-time itself."
"This special theory of relativity , was inconsistent with the Newtonian theory of gravity , which said that objects attracted each other with a force that depended on the distance between them.
In 1915 Einstein made the revolutionary suggestion that gravity is not a force like other forces"
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No useful information can be transmitted FTL.
Nice change.
What change?
Earth's gravity, denoted by g, refers to the attractive force that the Earth exerts on objects on or near its surface (or, more generally, objects anywhere in the Earth's vicinity).
As useful as the equivalence between gravitational and inertial effect might be, it does not constitute a complete theory of gravity. Notably, it cannot answer the following simple question: what keeps the people on the other side of the world from falling off? We might be able to explain gravity near our location on the Earth's surface as a fictitious force – as due to the fact that we have chosen a reference frame that is not in free fall. But a freely falling reference frame on our side of the Earth cannot explain why the people on the opposite side of the Earth experience a gravitational pull in the opposite direction.
A more subtle manifestation of the same effect involves two bodies that are falling side by side towards the Earth. In a reference frame that is in free fall alongside these bodies, they appear to hover weightlessly – but not completely so: after all, if you look more closely, these bodies are not falling in the same direction, but towards the same point in space: the Earth's center of gravity. Because of this, there is a minute component of motion bringing the two bodies ever closer to each other (see the image at right).
Whenever bodies fall in different directions or at different rates due to differences in the strength and direction of gravitational forces, we are dealing with what are called tidal effects (since such differences in force are also responsible for the tides in the Earth's oceans). The equivalence between inertia and gravity cannot explain these tidal effects – it cannot explain the variation of the gravitational field from location to location.[9]
How to recognize fictitious forces / accelerated reference frames
So, suppose we observe things moving in a way which suggests that forces are acting on them. How can we tell whether we are in an inertial reference frame, and the forces we observe are real, or whether we are in an accelerated reference frame, and the forces we observe are "fictitious"? The answer lies in the Force Law, which specifies that the acceleration which an object receives depends not only on the force acting on it, but also on its own mass, or inertia, or resistance to a change in its motion. For real forces, there is no guarantee that the force acting on the object and the mass of the object will produce a particular acceleration. The acceleration could be large or small, for a given force, depending upon how much inertia the object has. For fictitious forces, all objects seem to be accelerated in the same way, which means that the force acting on the objects seems to be directly proportional to the inertia of the object. Things that have little inertia seem to have little force acting on them, and things that have a lot of inertia seem to have a lot of force acting on them.
In mathematical terms, real forces Freal acting on different masses m will produce varying accelerations a, according to the rule
Freal = m a
where a could have any value, while fictitious forces Ffictitious acting on different masses will all produce the same acceleration aconstant, according to the rule
Ffictitious = m aconstant
So if we see different objects moving with different accelerations, at least some of those accelerations, and the forces causing them, must be real; whereas if we see different objects moving with the same acceleration, the accelerations are probably not real, but a mirror-image of an acceleration of the reference frame, and forces required to explain them are "fictitious".
Is Gravity A Fictitious Force?
There is one situation in which we see accelerations which are the same, and presume that the forces causing those accelerations are real -- namely, when we see objects falling toward the Earth, under the influence of gravity. No matter what the objects are made of, or how big or small they are, all objects fall under the influence of gravity with exactly the same acceleration, the acceleration of gravity. Solids, liquids, gases, green cheese, moonbeams, fairy dust and horsefeathers would all fall the same under the influence of gravity, as would sand grains, pebbles, boulders, mountains, moons and planets. Because of this we write the Force Law in a special way for the force of gravity, replacing the force F with the object's weight W, and the acceleration a with the acceleration of gravity, g, thusly
W = m g
The fact that gravity, like fictitious forces, involves a constant acceleration, makes us wonder whether gravity could be a fictitious force. It's hard to imagine that anything so pervasive and seemingly real could be "fictitious", but the forces experienced by the person in the accelerated car feel real, and are presumably fictitious. Is there some way that we could create the phenomenon of gravity, without the force?
There is indeed such a way. Suppose that you were in a rocket ship, headed upwards at the acceleration of gravity, so that anything not attached to the ship seems to "fall" with a mirror image of that upward acceleration. Then every such object would fall toward the back of the ship, at the acceleration of gravity, and trying to stop such a fall would require a force, in the direction of the acceleration, proportional to the object's mass, which would be equal to, and appear to be, its real weight.
Of course, we can't explain gravity in that way, as that would require every part of the Earth to be accelerating upward and outward, which would make the Earth bigger and bigger, which is not observed. So the simplest explanation is to assume that, peculiar though it may be, gravity -- although a perfectly real force -- acts as though it is a fictitious force. No other real force is known to act in this way, but perhaps gravity is "special", and it is merely a coincidence that it looks like a fictitious force.
The strange and in some ways disturbing answer to this supposition is that the phenomenon of gravity (the fact that things fall, and have weight) is real, but the force of gravity, as described by Newton, is not a real force, but a fictitious force. According to Einstein's General Theory of Relativity, gravity is a curvature of space-time such that in the future, things are closer together than they are now, even if they are moving in straight, parallel lines, with no force between them. For in curved space-time, there is no such thing as a straight line, but instead, only curved lines, called geodesics, which are the straightest possible paths in curved space-time, but are always and inexorably curved. (for now, see the chapter on black holes and general relativity in the text for a more detailed discussion) And since curved paths, in our experience, require some centripetal force to create them, the motion of things along geodesics seems to require some force to explain the acceleration observed, as a result of that curvature.
So we see things falling, with an acceleration which we call the acceleration of gravity, and thinking that we live in a straight-line, uniformly moving or stationary inertial reference frame, we attribute that acceleration to a force, the force of gravity. Whereas in reality, objects falling toward the Earth are moving along geodesic paths, with no acceleration, and according to a modified version of the Law of Inertia (objects which are at rest tend to remain at rest, and objects which are moving tend to move along geodesic paths with uniform motion, unless some force acts on them), have no force acting on them. They fall simply because the curved space-time near the Earth makes it natural for them to be closer to us in the future, than they are now.
But if no force is required to make them fall, why do they seem to have weight, when we hold them? In Newton's physics, the weight we perceive is a direct measure of the force of gravity acting on them. How can they have weight, if there is no force acting on them?
The answer is, that if we are holding them, there is a force acting on them, namely the upward force we are exerting, which keeps them from doing what they are supposed to do, namely fall. And of course that upward force on the object we're holding creates a reaction force, which is downward and equal to the upward force we are exerting, and that is what we are observing, when we observe that something has weight. In fact, even when we perceive our own weight, that is what we are observing. Whatever is keeping us from falling is pushing us upward, with a force equal to our "weight", and what we think is our weight, pushing downward, is just a reaction to that upward push. If there weren't anything pushing us upward -- if, for example, we were to jump off the top of the D building -- we would feel no upward force, and would therefore feel "weightless". We would presume that we weren't really weightless, because the ground is rapidly rising to meet us, but that isn't because we have weight, but because it is natural, in the absence of a force preventing it, for us to fall toward the Earth, along a space-time geodesic. (splat conveying the distinct notion that there's some force around here, somewhere, Einstein's Theory or not)
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Photons are not traveling at c because they are emitted at that speed. This has been shown by cooling a photon, which slows it, then warming it, which speeds it back up to c. If it can only attain a velocity of c during its initial emition, these types of experiments could never work.
How do you measure the temperature of a single photon?
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Photons are not traveling at c because they are emitted at that speed. This has been shown by cooling a photon, which slows it, then warming it, which speeds it back up to c. If it can only attain a velocity of c during its initial emition, these types of experiments could never work.
How do you measure the temperature of a single photon?
Well, first you get a really small thermometer. Then you hold the photon face down in one hand and the thermometer in the other. Then you gently insert .... Oh wait, wrong forum, never mind.
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No useful information can be transmitted FTL.
Nice change.
What change?
Earth's gravity, denoted by g, refers to the attractive force that the Earth exerts on objects on or near its surface (or, more generally, objects anywhere in the Earth's vicinity).
I thought g meant grams =/
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As useful as the equivalence between gravitational and inertial effect might be, it does not constitute a complete theory of gravity. Notably, it cannot answer the following simple question: what keeps the people on the other side of the world from falling off?
I find it quite strange that a supposed university instructor would constantly refer to GR as just the EP.
Like I said earlier, I may just have to stop responding, as you will just prove me right all on your own. From your own post:
The strange and in some ways disturbing answer to this supposition is that the phenomenon of gravity (the fact that things fall, and have weight) is real, but the force of gravity, as described by Newton, is not a real force, but a fictitious force. According to Einstein's General Theory of Relativity, gravity is a curvature of space-time such that in the future, things are closer together than they are now, even if they are moving in straight, parallel lines, with no force between them. For in curved space-time, there is no such thing as a straight line, but instead, only curved lines, called geodesics, which are the straightest possible paths in curved space-time, but are always and inexorably curved. (for now, see the chapter on black holes and general relativity in the text for a more detailed discussion) And since curved paths, in our experience, require some centripetal force to create them, the motion of things along geodesics seems to require some force to explain the acceleration observed, as a result of that curvature.
So we see things falling, with an acceleration which we call the acceleration of gravity, and thinking that we live in a straight-line, uniformly moving or stationary inertial reference frame, we attribute that acceleration to a force, the force of gravity. Whereas in reality, objects falling toward the Earth are moving along geodesic paths, with no acceleration, and according to a modified version of the Law of Inertia (objects which are at rest tend to remain at rest, and objects which are moving tend to move along geodesic paths with uniform motion, unless some force acts on them), have no force acting on them. They fall simply because the curved space-time near the Earth makes it natural for them to be closer to us in the future, than they are now.
But if no force is required to make them fall, why do they seem to have weight, when we hold them? In Newton's physics, the weight we perceive is a direct measure of the force of gravity acting on them. How can they have weight, if there is no force acting on them?
The answer is, that if we are holding them, there is a force acting on them, namely the upward force we are exerting, which keeps them from doing what they are supposed to do, namely fall. And of course that upward force on the object we're holding creates a reaction force, which is downward and equal to the upward force we are exerting, and that is what we are observing, when we observe that something has weight. In fact, even when we perceive our own weight, that is what we are observing. Whatever is keeping us from falling is pushing us upward, with a force equal to our "weight", and what we think is our weight, pushing downward, is just a reaction to that upward push. If there weren't anything pushing us upward -- if, for example, we were to jump off the top of the D building -- we would feel no upward force, and would therefore feel "weightless". We would presume that we weren't really weightless, because the ground is rapidly rising to meet us, but that isn't because we have weight, but because it is natural, in the absence of a force preventing it, for us to fall toward the Earth, along a space-time geodesic. (splat conveying the distinct notion that there's some force around here, somewhere, Einstein's Theory or not)
I bolded and made the important parts bigger, as you seem to have a really hard time reading. Thank you for making this so easy, you are a real help. Good job, you get a gold star!
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As useful as the equivalence between gravitational and inertial effect might be, it does not constitute a complete theory of gravity. Notably, it cannot answer the following simple question: what keeps the people on the other side of the world from falling off?
I find it quite strange that a supposed university instructor would constantly refer to GR as just the EP.
Like I said earlier, I may just have to stop responding, as you will just prove me right all on your own. From your own post:
....
I bolded and made the important parts bigger, as you seem to have a really hard time reading. Thank you for making this so easy, you are a real help. Good job, you get a gold star!
Where do I say that the GR is just the EP? You used a quote from Wikipedia to build your straw man.
I know that it goes against your principles, but I quote entire articles, even when sections, taken out of context, don't support me. I suggest that you try reading the entire posting. Oh, and if you get the chance, try being honest too.
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Like I said earlier, I may just have to stop responding, as you will just prove me right all on your own.
Gulliver the Hypocrite's good at that! ;D
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I know that it goes against your principles, but I quote entire articles, even when sections, taken out of context, don't support me. I suggest that you try reading the entire posting. Oh, and if you get the chance, try being honest too.
So your own source proves you wrong, so you cry about it being taken out of context?
That's an evasion tactic even TomB would be proud of.
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I know that it goes against your principles, but I quote entire articles, even when sections, taken out of context, don't support me. I suggest that you try reading the entire posting. Oh, and if you get the chance, try being honest too.
So your own source proves you wrong, so you cry about it being taken out of context?
That's an evasion tactic even TomB would be proud of.
The source proves me correct.
As useful as the equivalence between gravitational and inertial effect might be, it does not constitute a complete theory of gravity. Notably, it cannot answer the following simple question: what keeps the people on the other side of the world from falling off? We might be able to explain gravity near our location on the Earth's surface as a fictitious force – as due to the fact that we have chosen a reference frame that is not in free fall. But a freely falling reference frame on our side of the Earth cannot explain why the people on the opposite side of the Earth experience a gravitational pull in the opposite direction.
Of course, we can't explain gravity in that way, as that would require every part of the Earth to be accelerating upward and outward, which would make the Earth bigger and bigger, which is not observed. So the simplest explanation is to assume that, peculiar though it may be, gravity -- although a perfectly real force -- acts as though it is a fictitious force. No other real force is known to act in this way, but perhaps gravity is "special", and it is merely a coincidence that it looks like a fictitious force.
[C]onveying the distinct notion that there's some force around here, somewhere, Einstein's Theory or not
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Oh and speaking of evading... Where's the FoR and explanation of how gravity as a force isn't need in the two-person on opposite sides of the Earth that we need to get into Wikipedia? Where's that quote from Einstein that "gravity as a force does not exist"? Where's that proof that nature is an observer? Where's that reference after 1998 that Nature does not send information FTL? That's four open issues that you've been evading for almost a whole day.
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Like I said earlier, I may just have to stop responding, as you will just prove me right all on your own.
Gulliver the Hypocrite's good at that! ;D
Do we need to have that argument again? You already conceded once. Geesh, some people.
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I know that it goes against your principles, but I quote entire articles, even when sections, taken out of context, don't support me. I suggest that you try reading the entire posting. Oh, and if you get the chance, try being honest too.
So your own source proves you wrong, so you cry about it being taken out of context?
That's an evasion tactic even TomB would be proud of.
The source proves me correct.
As useful as the equivalence between gravitational and inertial effect might be, it does not constitute a complete theory of gravity. Notably, it cannot answer the following simple question: what keeps the people on the other side of the world from falling off? We might be able to explain gravity near our location on the Earth's surface as a fictitious force – as due to the fact that we have chosen a reference frame that is not in free fall. But a freely falling reference frame on our side of the Earth cannot explain why the people on the opposite side of the Earth experience a gravitational pull in the opposite direction.
Of course, we can't explain gravity in that way, as that would require every part of the Earth to be accelerating upward and outward, which would make the Earth bigger and bigger, which is not observed. So the simplest explanation is to assume that, peculiar though it may be, gravity -- although a perfectly real force -- acts as though it is a fictitious force. No other real force is known to act in this way, but perhaps gravity is "special", and it is merely a coincidence that it looks like a fictitious force.
[C]onveying the distinct notion that there's some force around here, somewhere, Einstein's Theory or not
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Oh and speaking of evading... Where's the FoR and explanation of how gravity as a force isn't need in the two-person on opposite sides of the Earth that we need to get into Wikipedia? Where's that quote from Einstein that "gravity as a force does not exist"? Where's that proof that nature is an observer? Where's that reference after 1998 that Nature does not send information FTL? That's four open issues that you've been evading for almost a whole day.
The curvature in spacetime keeps them from falling off. You're right in saying that the Equivalence Principle is not a full theory of gravitation. General Relativity, however, is. The Equivalence Principle is what led Einstein to develop General Relativity, in which SPACETIME BENDS, to be a better theory of gravitation.
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I'll post again:
"It occurred to Einstein – thinking first of all in visual terms, as was usual for him – that if a man were falling from the roof of his house and tried to let anything drop, it would only move alongside him, thus indicating the equivalence of acceleration and gravity. In Einstein's words, "the acceleration of free fall with respect to the material is therefore a mighty argument that the postulate of relativity is to be extended to coordinate systems that move nonuniformly relative to one another . . . .""
- http://www.aip.org/history/einstein/essay-einsteins-third-paradise.htm
"Einstein said that gravity is a function of mass alright but not as a force exerted by the mass! To the scientists of his day these words amounted to scientific heresy. If gravity is not a force, they asked, then what is it? Einstein's answer is no less than life changing! Gravity, he said, is the result of the mass of an object bending space! Bending Space! Can you imagine? I cannot!
What Einstein was saying is that objects do not fall because of an attractive force reaching out of an object and pulling it to itself, as Newton said."
"Einstein revolutionized modern science by putting forward the theory that gravity is not a force like other forces, but is a result of the fact that space-time is not flat."
"About 50 years ago, Albert Einstein gave us a revolutionary explanation for the gravity we are familiar with. Einstein said gravity is not a force of attraction, as Isaac Newton described it, but rather, comes from the warping of space-time itself."
"This special theory of relativity , was inconsistent with the Newtonian theory of gravity , which said that objects attracted each other with a force that depended on the distance between them.
In 1915 Einstein made the revolutionary suggestion that gravity is not a force like other forces"
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Is Gravity A Fictitious Force?
There is one situation in which we see accelerations which are the same, and presume that the forces causing those accelerations are real -- namely, when we see objects falling toward the Earth, under the influence of gravity. No matter what the objects are made of, or how big or small they are, all objects fall under the influence of gravity with exactly the same acceleration, the acceleration of gravity. Solids, liquids, gases, green cheese, moonbeams, fairy dust and horsefeathers would all fall the same under the influence of gravity, as would sand grains, pebbles, boulders, mountains, moons and planets. Because of this we write the Force Law in a special way for the force of gravity, replacing the force F with the object's weight W, and the acceleration a with the acceleration of gravity, g, thusly
W = m g
The fact that gravity, like fictitious forces, involves a constant acceleration, makes us wonder whether gravity could be a fictitious force. It's hard to imagine that anything so pervasive and seemingly real could be "fictitious", but the forces experienced by the person in the accelerated car feel real, and are presumably fictitious. Is there some way that we could create the phenomenon of gravity, without the force?
There is indeed such a way. Suppose that you were in a rocket ship, headed upwards at the acceleration of gravity, so that anything not attached to the ship seems to "fall" with a mirror image of that upward acceleration. Then every such object would fall toward the back of the ship, at the acceleration of gravity, and trying to stop such a fall would require a force, in the direction of the acceleration, proportional to the object's mass, which would be equal to, and appear to be, its real weight.
Of course, we can't explain gravity in that way, as that would require every part of the Earth to be accelerating upward and outward, which would make the Earth bigger and bigger, which is not observed. So the simplest explanation is to assume that, peculiar though it may be, gravity -- although a perfectly real force -- acts as though it is a fictitious force. No other real force is known to act in this way, but perhaps gravity is "special", and it is merely a coincidence that it looks like a fictitious force.
The strange and in some ways disturbing answer to this supposition is that the phenomenon of gravity (the fact that things fall, and have weight) is real, but the force of gravity, as described by Newton, is not a real force, but a fictitious force. According to Einstein's General Theory of Relativity, gravity is a curvature of space-time such that in the future, things are closer together than they are now, even if they are moving in straight, parallel lines, with no force between them. For in curved space-time, there is no such thing as a straight line, but instead, only curved lines, called geodesics, which are the straightest possible paths in curved space-time, but are always and inexorably curved. (for now, see the chapter on black holes and general relativity in the text for a more detailed discussion) And since curved paths, in our experience, require some centripetal force to create them, the motion of things along geodesics seems to require some force to explain the acceleration observed, as a result of that curvature.
So we see things falling, with an acceleration which we call the acceleration of gravity, and thinking that we live in a straight-line, uniformly moving or stationary inertial reference frame, we attribute that acceleration to a force, the force of gravity. Whereas in reality, objects falling toward the Earth are moving along geodesic paths, with no acceleration, and according to a modified version of the Law of Inertia (objects which are at rest tend to remain at rest, and objects which are moving tend to move along geodesic paths with uniform motion, unless some force acts on them), have no force acting on them. They fall simply because the curved space-time near the Earth makes it natural for them to be closer to us in the future, than they are now.
But if no force is required to make them fall, why do they seem to have weight, when we hold them? In Newton's physics, the weight we perceive is a direct measure of the force of gravity acting on them. How can they have weight, if there is no force acting on them?
The answer is, that if we are holding them, there is a force acting on them, namely the upward force we are exerting, which keeps them from doing what they are supposed to do, namely fall. And of course that upward force on the object we're holding creates a reaction force, which is downward and equal to the upward force we are exerting, and that is what we are observing, when we observe that something has weight. In fact, even when we perceive our own weight, that is what we are observing. Whatever is keeping us from falling is pushing us upward, with a force equal to our "weight", and what we think is our weight, pushing downward, is just a reaction to that upward push. If there weren't anything pushing us upward -- if, for example, we were to jump off the top of the D building -- we would feel no upward force, and would therefore feel "weightless". We would presume that we weren't really weightless, because the ground is rapidly rising to meet us, but that isn't because we have weight, but because it is natural, in the absence of a force preventing it, for us to fall toward the Earth, along a space-time geodesic. (splat conveying the distinct notion that there's some force around here, somewhere, Einstein's Theory or not)
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I'll post again:
"It occurred to Einstein – thinking first of all in visual terms, as was usual for him – that if a man were falling from the roof of his house and tried to let anything drop, it would only move alongside him, thus indicating the equivalence of acceleration and gravity. In Einstein's words, "the acceleration of free fall with respect to the material is therefore a mighty argument that the postulate of relativity is to be extended to coordinate systems that move nonuniformly relative to one another . . . .""
- http://www.aip.org/history/einstein/essay-einsteins-third-paradise.htm
"Einstein said that gravity is a function of mass alright but not as a force exerted by the mass! To the scientists of his day these words amounted to scientific heresy. If gravity is not a force, they asked, then what is it? Einstein's answer is no less than life changing! Gravity, he said, is the result of the mass of an object bending space! Bending Space! Can you imagine? I cannot!
What Einstein was saying is that objects do not fall because of an attractive force reaching out of an object and pulling it to itself, as Newton said."
"Einstein revolutionized modern science by putting forward the theory that gravity is not a force like other forces, but is a result of the fact that space-time is not flat."
"About 50 years ago, Albert Einstein gave us a revolutionary explanation for the gravity we are familiar with. Einstein said gravity is not a force of attraction, as Isaac Newton described it, but rather, comes from the warping of space-time itself."
"This special theory of relativity , was inconsistent with the Newtonian theory of gravity , which said that objects attracted each other with a force that depended on the distance between them.
In 1915 Einstein made the revolutionary suggestion that gravity is not a force like other forces"
I'll post it again: Wikipedia (http://en.wikipedia.org/wiki/Introduction_to_general_relativity#Tidal_effects)
As useful as the equivalence between gravitational and inertial effect might be, it does not constitute a complete theory of gravity. Notably, it cannot answer the following simple question: what keeps the people on the other side of the world from falling off? We might be able to explain gravity near our location on the Earth's surface as a fictitious force – as due to the fact that we have chosen a reference frame that is not in free fall. But a freely falling reference frame on our side of the Earth cannot explain why the people on the opposite side of the Earth experience a gravitational pull in the opposite direction.
A more subtle manifestation of the same effect involves two bodies that are falling side by side towards the Earth. In a reference frame that is in free fall alongside these bodies, they appear to hover weightlessly – but not completely so: after all, if you look more closely, these bodies are not falling in the same direction, but towards the same point in space: the Earth's center of gravity. Because of this, there is a minute component of motion bringing the two bodies ever closer to each other (see the image at right).
Whenever bodies fall in different directions or at different rates due to differences in the strength and direction of gravitational forces, we are dealing with what are called tidal effects (since such differences in force are also responsible for the tides in the Earth's oceans). The equivalence between inertia and gravity cannot explain these tidal effects – it cannot explain the variation of the gravitational field from location to location.[9]
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You cannot find the FoRs in the two persons on opposite sides of the Earth to eliminate gravity as a force. Einstein even said so himself. You need to stop trying to simplify an analogy to help us understand the Universe into the incorrect statement: "gravity as a force does not exist" until you can provide a solution without gravity as a force to describe that situation.
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I'll post again:
Hey! That's the same thing TomB does when he has lost.
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I'll post again:
Hey! That's the same thing TomB does when he has lost.
Hey! You're still avoiding all those challenges, just like TomB does when he can't answer them!
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What challenges is he avoiding?
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What challenges is he avoiding?
My money says Gulliver is currently arguing for whatever he started arguing against. Any takers? I'll give you great odds.
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What challenges is he avoiding?
My money says Gulliver is currently arguing for whatever he started arguing against. Any takers? I'll give you great odds.
I'm in for $1,000,000.00 US.
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What challenges is he avoiding?
My money says Gulliver is currently arguing for whatever he started arguing against. Any takers? I'll give you great odds.
I'm in for $1,000,000.00 US.
(you need the cash to start with G...)
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What challenges is he avoiding?
My money says Gulliver is currently arguing for whatever he started arguing against. Any takers? I'll give you great odds.
I'm in for $1,000,000.00 US.
(you need the cash to start with G...)
If you insist on cash, then I'll have to settle for just $700,000. Oh, and at great odds, say two to one, you'll need $1.4 million in cash to cover.
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What challenges is he avoiding?
...
Oh and speaking of evading... Where's the FoR and explanation of how gravity as a force isn't need in the two-person on opposite sides of the Earth that we need to get into Wikipedia? Where's that quote from Einstein that "gravity as a force does not exist"? Where's that proof that nature is an observer? Where's that reference after 1998 that Nature does not send information FTL? That's four open issues that you've been evading for almost a whole day.
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The first one has been answered. Consult the other thread where THE SAME EXACT THING is being debated.
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The first one has been answered. Consult the other thread where THE SAME EXACT THING is being debated.
You asked for a list. I provided it. I also disagree that the first one has been answered.
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The first one has been answered. Consult the other thread where THE SAME EXACT THING is being debated.
You asked for a list. I provided it. I also disagree that the first one has been answered.
Just because you disagree doesn't mean it was avoided. My point about staying in the other thread is to keep the arguments in one place.
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The first one has been answered. Consult the other thread where THE SAME EXACT THING is being debated.
You asked for a list. I provided it. I also disagree that the first one has been answered.
Just because you disagree doesn't mean it was avoided. My point about staying in the other thread is to keep the arguments in one place.
I maintain that the answer was nothing more than Theengineer's standard "horses and the feathers that they don't have" evasion. He just throws out nouns without making a case when he gets in trouble with his statements. If he make even a worthy attempt, I would agree with you.
If you wanted a list of items avoided only in this thread, then I suggest you might have asked for that.
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Well, it's official. Gulliver sux.
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His own source proves him wrong, so it must be that the article, in its entirety no less, is now out of context. But prior to this realization, the article was just fine, in its entirety, no less.
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Well, it's official. Gulliver sux.
That was official a long time ago.
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I like pork.
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I'll keep that in mind when your birthday comes around.
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His own source proves him wrong, so it must be that the article, in its entirety no less, is now out of context. But prior to this realization, the article was just fine, in its entirety, no less.
Still waiting on that quote from Einstein that "gravity as a force does not exist". Still waiting on your proof that Nature is an observer. Still waiting on any proof that the 1998 AIP web page is wrong about Nature sending info FTL. I will consider your geodesics explanation, but still haven't seen any evidence that Einstein thought we should stop treating gravity as a force in all cases.
Oh, and I will be the better man and avoid insulting you, for now anyway.
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Oh, and please ratchet up the quality of your references. Wikipedia just pales so much against APL, don't you think?
No.
If what you are saying is that Wikipedia is a reliable source of information, then
The Earth's shape is very close to an oblate spheroid—a rounded shape with a bulge around the equator—although the precise shape (the geoid) varies from this by up to 100 metres (327 ft).[18]
and the Earth is round.
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I think just quoting wikipedia just shows that you lack a solid understanding of the subject, if you had a good working knowledge of the subject then it see,s that you should be able to properly explain it yourself, I think the only links should be to where actual studies have been done so we can read them ourselves.
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I think just quoting wikipedia just shows that you lack a solid understanding of the subject, if you had a good working knowledge of the subject then it see,s that you should be able to properly explain it yourself, I think the only links should be to where actual studies have been done so we can read them ourselves.
I'm not going to teach every noob that comes along General Relativity. You are perfectly capable of doing research on your own. I can point you in a direction, and, if you are not too lazy, you can do some reading for yourself.
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and yet when someone defends a statement that they have made that person should be able to explain the stance that they took in thier own words, not just quote what somone else said because it sounds smart.
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and yet when someone defends a statement that they have made that person should be able to explain the stance that they took in thier own words, not just quote what somone else said because it sounds smart.
It's amazing that people will assume that anything said by an 'FE'er' must be wrong, just because they are an 'FE'er.'
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I think just quoting wikipedia just shows that you lack a solid understanding of the subject, if you had a good working knowledge of the subject then it see,s that you should be able to properly explain it yourself, I think the only links should be to where actual studies have been done so we can read them ourselves.
The main point of my argument was not to use Wikipedia as a source. I agree with you 100%. But in in previous post, FE'ers cited Wikipedia and also said that it was a credible source. If they are willing to accept this, then I have refuted their beliefs.
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I think just quoting wikipedia just shows that you lack a solid understanding of the subject, if you had a good working knowledge of the subject then it see,s that you should be able to properly explain it yourself, I think the only links should be to where actual studies have been done so we can read them ourselves.
Do you have one source that is better?
Explaining something yourself allows people to question your words. Using sources allows for points to be better made, and understood.
Just because Wikipedia happens to allow revision doesn't make it any less credible, nor does it mean you don't understand what you're reading.
Wikipedia also makes it easier to get a concise summary. Googling something incredibly specific for use as a source would be time-consuming and there'd be no guarantee you'd find anything.
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<snip>
Explaining something yourself allows people to question your words. Using sources allows for points to be better made, and understood.
Just because Wikipedia happens to allow revision doesn't make it any less credible, nor does it mean you don't understand what you're reading.
Wikipedia also makes it easier to get a concise summary. Googling something incredibly specific for use as a source would be time-consuming and there'd be no guarantee you'd find anything.
Perhaps. I must admit, however, that explaining something in your own words does demonstrate a better understanding of the subject. Here’s what pisses me off Divito, I have read this entire thread as well as others in this forum with similar topics and am now not sure who believes what!?
TheEngineer is clearly an intelligent, educated individual that invokes very interesting, spirited discussions, many of which I’ve learned from. However, he seems to exist on this forum merely to antagonize Gulliver (TomG?). And Gulliver seems to be some kind of strange conduit to Wikipedia!?
The rest of the cast on this forum merely exists to fill in the gaps between their (TE and TG’s) posts. At first I was intrigued, now I’m simply bored with the whole damn thing… ???
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Perhaps. I must admit, however, that explaining something in your own words does demonstrate a better understanding of the subject. Here’s what pisses me off Divito, I have read this entire thread as well as others in this forum with similar topics and am now not sure who believes what!?
TheEngineer is clearly an intelligent, educated individual that invokes very interesting, spirited discussions, many of which I’ve learned from. However, he seems to exist on this forum merely to antagonize Gulliver (TomG?). And Gulliver seems to be some kind of strange conduit to Wikipedia!?
The rest of the cast on this forum merely exists to fill in the gaps between their (TE and TG’s) posts. At first I was intrigued, now I’m simply bored with the whole damn thing… ???
It has gotten rather repetitive lately, which is unfortunate. But that's only because when someone makes a claim and it goes through the debate process, we arrive at the same simple disagreements.
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His own source proves him wrong, so it must be that the article, in its entirety no less, is now out of context. But prior to this realization, the article was just fine, in its entirety, no less.
Still waiting on that quote from Einstein that "gravity as a force does not exist". Still waiting on your proof that Nature is an observer. Still waiting on any proof that the 1998 AIP web page is wrong about Nature sending info FTL. I will consider your geodesics explanation, but still haven't seen any evidence that Einstein thought we should stop treating gravity as a force in all cases.
Um, I don't recall anyone saying that we should stop treating gravity as a force in all cases. I recall TheEngineer saying that gravity is a fake force. There's a difference. We can treat it like a force when we're dealing with it, but that doesn't make it a force.
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His own source proves him wrong, so it must be that the article, in its entirety no less, is now out of context. But prior to this realization, the article was just fine, in its entirety, no less.
Still waiting on that quote from Einstein that "gravity as a force does not exist". Still waiting on your proof that Nature is an observer. Still waiting on any proof that the 1998 AIP web page is wrong about Nature sending info FTL. I will consider your geodesics explanation, but still haven't seen any evidence that Einstein thought we should stop treating gravity as a force in all cases.
Um, I don't recall anyone saying that we should stop treating gravity as a force in all cases. I recall TheEngineer saying that gravity is a fake force. There's a difference. We can treat it like a force when we're dealing with it, but that doesn't make it a force.
You and I agree about gravity. TheEngineer, though, claims that Einstein said "gravity as a force does not exist." and that this arises from a shift of FoR.
See, for example: Does not acceleration require a force? That force is gravity.
Actually, no. We are in a non inertial frame of reference, thus, by definition, Newton's first two laws don't apply. Since we perceive ourselves as not accelerating, we transform our frame of reference into an inertial one. This transformation gives rise to fictitious forces, namely, gravity.
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Yes, gulliver, but that acceleration only exists if you think of spacetime being Euclidean. When you think of it not being Euclidean, as GR describes, no force is necessary for that 'gravity'.
EDIT: Also, TheEngineer never said to not treat it as a force, he just said it isn't a force.
EDIT2: Changed 'space' to 'spacetime'
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You and I agree about gravity. TheEngineer, though, claims that Einstein said "gravity as a force does not exist."
I'm sure he didn't say that specific quote (Einstein).
It's true that TheEngineer did say that, but he's clearly wrong or he meant that Einstein's work revealed that conclusion. Since TheEngineer is rarely wrong, I'm guessing it's the latter.
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Yes, information transfer at FTL speeds is strictly prohibited by GR. Things can move at FTL speeds, but they can't tell us they are doing so. This would cause all kinds of problems with causality, so there is usually a very neat mathematical solution as to why information can't be transfered at FTL speeds. Such as a tachyon detector: It would be able to detect the incoming tachyon, but it would also emit an exact copy of that tachyon, thus losing the information.
What if FTL particles are reduced in speed to c?
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Yes, information transfer at FTL speeds is strictly prohibited by GR. Things can move at FTL speeds, but they can't tell us they are doing so. This would cause all kinds of problems with causality, so there is usually a very neat mathematical solution as to why information can't be transfered at FTL speeds. Such as a tachyon detector: It would be able to detect the incoming tachyon, but it would also emit an exact copy of that tachyon, thus losing the information.
What if FTL particles are reduced in speed to c?
Not possible. The existence of FTLs relies on them always being faster than light. In other words, by definition, they are always moving superluminally.
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What if FTL particles are reduced in speed to c?
That would require an acceleration to c, which is prohibited.
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So are you saying superliminal particles like tachyons cannot be distorted nor decelerated to or lower than c when transversing through a medium?
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So are you saying superliminal particles like tachyons cannot be distorted nor decelerated to or lower than c when transversing through a medium?
Yes.
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So are you saying superliminal particles like tachyons cannot be distorted nor decelerated to or lower than c when transversing through a medium?
Yes.
I think I disagree, on a technicality. (This is really hypothetical stuff.) c[/c] is the speed of light in a vacuum. A very energetic tachyon traveling through a very dense medium could very well travel more slowly than c[/c], but never as slow as light would travel in the same medium (which is what I think Fritz meant).
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So are you saying superliminal particles like tachyons cannot be distorted nor decelerated to or lower than c when transversing through a medium?
Yes.
::)
I think I disagree, on a technicality. (This is really hypothetical stuff.) c[/c] is the speed of light in a vacuum. A very energetic tachyon traveling through a very dense medium could very well travel more slowly than c[/c], but never as slow as light would travel in the same medium (which is what I think Fritz meant).
Thank you. This simple demonstration shows that the current GR theory needs revisions in its definitions.
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<snip>
Thank you. This simple demonstration shows that the current GR theory needs revisions in its definitions.
No shit Sherlock! ???
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So are you saying superliminal particles like tachyons cannot be distorted nor decelerated to or lower than c when transversing through a medium?
Yes.
::)
I think I disagree, on a technicality. (This is really hypothetical stuff.) c[/c] is the speed of light in a vacuum. A very energetic tachyon traveling through a very dense medium could very well travel more slowly than c[/c], but never as slow as light would travel in the same medium (which is what I think Fritz meant).
Thank you. This simple demonstration shows that the current GR theory needs revisions in its definitions.
The current GR theory needs more revisions than that. It is simply a model of gravitation which is better able to predict the effects of gravity than Newton's gravity. In this model, there are many problems (things which happen on a very small scale do not agree with GR).
I think that 99% of the posters on here referring do GR do not understand GR as well as they claim. (I'm not claiming that I understand it either, as I do not!)
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I think that 99% of the posters on here referring do GR do not understand GR as well as they claim. (I'm not claiming that I understand it either, as I do not!)
How can these two statements go together?
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I think that 99% of the posters on here referring do GR do not understand GR as well as they claim. (I'm not claiming that I understand it either, as I do not!)
How can these two statements go together?
I am not a physicist, and I have not read books or papers on GR, but I have taken a course in Differential Geometry, I am soon to take a course in GR, and I know a relativist quite well, and we talk about GR a little bit. I am not a stupid person!
Gravity is the reason that objects fall to the Earths surface, whether it is a force or not. To my understanding, the theory of GR assumes that the universe is a 4D manifold which is curved by mass, and objects follow geodesics on this manifold, which happen to cause them to move towards sources of mass. Either way, it pulls things downwards, so it is irrelevant to us whether it is a force or not.
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I am not a stupid person!
No one said you were.
Gravity is the reason that objects fall to the Earths surface
Gravitation is the reason objects fall to the Earth's surface. This is not a force, in GR. So yes, it does matter.
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Gravity is the reason that objects fall to the Earths surface
Gravitation is the reason objects fall to the Earth's surface. This is not a force, in GR.
This is exactly what I said, so I am done arguing this point.
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Gravity is the reason that objects fall to the Earths surface
Gravitation is the reason objects fall to the Earth's surface. This is not a force, in GR.
This is exactly what I said, so I am done arguing this point.
No, you said gravity. He said gravitation. They are different.
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gravity and gravitationare interchangeable just like we can say kilograms or pounds when we really mean Newtons or Slugs, I really do not see you guys going to the butcher and ordering 2 Newtons of beef, and no gravity(gravitation) is not a force but it is a cause of a force.
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gravity and gravitationare interchangeable just like we can say kilograms or pounds when we really mean Newtons or Slugs, I really do not see you guys going to the butcher and ordering 2 Newtons of beef, and no gravity(gravitation) is not a force but it is a cause of a force.
"In scientific terminology gravitation and gravity are distinct." - Source (http://en.wikipedia.org/wiki/Gravity)
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Typically, physicists will look at photons as waves for your thought argument. This allows them to ignore their mass. They will then look at them as particles when they need them to have mass. Basically we have the newtonian vs quantum laws that we pick and choose from. This is evidence that we have a flaw in our model at a more elementary level.
Photons do not have mass. They have momentum...
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gravity and gravitationare interchangeable just like we can say kilograms or pounds when we really mean Newtons or Slugs, I really do not see you guys going to the butcher and ordering 2 Newtons of beef, and no gravity(gravitation) is not a force but it is a cause of a force.
"In scientific terminology gravitation and gravity are distinct." - Source (http://en.wikipedia.org/wiki/Gravity)
This is a useless argument. I'm sorry if I didn't use the word gravitation when I meant gravity. While reading/writing this forum, I don't really think much about scientific terminology as it is not particularly scientifically accurate.
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This is a useless argument. I'm sorry if I didn't use the word gravitation when I meant gravity. While reading/writing this forum, I don't really think much about scientific terminology as it is not particularly scientifically accurate.
You're forgiven. Just, if you want to avoid useless arguments, it helps to use the appropriate terms. It disallows people from attacking your sentence formation and use of inaccurate words as evidenced by the last few posts.