"Falling" towards the earth

Quote from: trig on April 17, 2009, 07:24:10 PM

There is clear evidence for the distortion of space-time due to big masses or high speeds. no evidence for speeds higher than c.

There is also no evidence that black holes or gravitons exist; we haven't observed them directly. There goes that "scientific method"...

Get your facts straight: there is evidence of the existence of black holes, even though it is impossible to see one directly.

There is overwhelming evidence for gravitational pull, even though we are still just speculating about what a graviton should be. No scientist says direct observation of a phenomenon is required to have evidence of its existence. We had learned volumes about viruses, for example, before we had the first glimpse of their shape. In fact we eliminated one species of virus from the human population before we could say we had "seen" a virus.

There is no mention at all about "direct observation" in any definition or explanation of the scientific method I have seen. Quite the opposite, the scientific method is most useful when there is no way to observe a phenomenon directly.

I already showed you a scientist. Here's another one theorizing hyperspace FTL using GR. As for evidence, why don't you say that to modern theoretical physics, such as gravitons, superforce, and supersymmetry. What happens to your scientific method now? Are these theories wrong?

Get your definitions straight: "theory" is the highest level of knowledge in science. An idea reaches the level of theory when there is a model, a decisive set of experiments and observations and an important set of verified predictions.

Theoretical physics has an important place in science but they do not produce evidence for any hypothesis. They produce possible models that might some day be tested and become theories.

So, to answer your question, those are not theories, they are possibilities, hypothesis, mathematical proofs that something is possible or impossible. They are the first step in the scientific method, where a model is devised so that someone can devise experiments or observations that might eventually give the idea the status of theory.

Quote from: trig on April 18, 2009, 01:19:11 AM

Get your facts straight: there is evidence of the existence of black holes, even though it is impossible to see one directly.

Then can you prove that no civilizations in the universe ever traveled faster than the speed of light, relative to an outside observer, through shortcuts in distorted space-time? Like black holes, we haven't seen one doing that, but can you prove it isn't possible?

I doubt you can.

Quote from: trig on April 18, 2009, 01:19:11 AM

There is overwhelming evidence for gravitational pull, even though we are still just speculating about what a graviton should be. No scientist says direct observation of a phenomenon is required to have evidence of its existence. We had learned volumes about viruses, for example, before we had the first glimpse of their shape. In fact we eliminated one species of virus from the human population before we could say we had "seen" a virus.

There is no mention at all about "direct observation" in any definition or explanation of the scientific method I have seen. Quite the opposite, the scientific method is most useful when there is no way to observe a phenomenon directly.

Right, therefore, just because we haven't seen one making a wormhole and traveling through it, doesn't mean it isn't possible. You asked for evidence, I said what about gravitons, then you said it doesn't have to be observed to be proven. Same here, no one observes a wormhole, yet it's theoretically possible just like a graviton. You're just twisting your argument to fit what's best for you.

Anyone past the Junior High physics courses will explain to you that current science does not deny the possibility that extraterrestrials might travel faster than the speed of light and does not deny the possibility that extraterrestrials do not even exist. Science stops where nothing else can be inferred from available evidence.

By the way, General Relativity is considered a theory since the first experimental validations were made around 1919, when gravitational lensing by the sun was observed during a solar eclipse and was further validated when the predictions made by Einstein about the orbit of Mercury were confirmed. You see, since 1905 or so until 1919 General Relativity was speculation, and since then it has gradually become a theory.

Quote from: trig on April 18, 2009, 07:42:29 AM

Anyone past the Junior High physics courses will explain to you that current science does not deny the possibility that extraterrestrials might travel faster than the speed of light and does not deny the possibility that extraterrestrials do not even exist. Science stops where nothing else can be inferred from available evidence.

Then stop asking for evidence on FTL possibilities.

You asked for evidence, I said what about gravitons, then you said it doesn't have to be observed to be proven. Same here, no one observes a wormhole, yet it's theoretically possible just like a graviton. You're just twisting your argument to fit what's best for you.

Supersymmetry is a theory...

And since this is a symmetry, this operator must commute with the Hamiltonian. Such a theory is called a supersymmetric theory, and the operator Q is called the supercharge. Since the supercharge corresponds to an operator that changes a particle with spin one half to a particle with spin one or zero, the supercharge itself must be a spinor that carries one half unit of spin of its own.

You asked for evidence, I said what about gravitons, then you said it doesn't have to be observed to be proven. Same here, no one observes a wormhole, yet it's theoretically possible just like a graviton. You're just twisting your argument to fit what's best for you.

Where, exactly did you find that "we have to know everything" principle?

But science has no place for "special cases" where some laws apply "on Earth" and others apply "off Earth"

I welcome the debate you say you want. Please show us the models you want to discuss and the predictions you can make based on the model, together with the experimental results on which you base your case for your model. But please, if you do not understand the scientific method, do not bother replying.

Quote from: trig on April 17, 2009, 03:24:29 PM

Where, exactly did you find that "we have to know everything" principle?

Quote from: trig

But science has no place for "special cases" where some laws apply "on Earth" and others apply "off Earth"

Quote

I welcome the debate you say you want. Please show us the models you want to discuss and the predictions you can make based on the model, together with the experimental results on which you base your case for your model. But please, if you do not understand the scientific method, do not bother replying.

I am acquainted with the scientific method - that is why we have even gotten this far in this debate. FET has made predictions (such as the impossibility of sustained spaceflight), and it is those that we are here to debate and assess.

Inertial motion = a motion without acceleration.

You don't fall faster. It's relativity physics. In your frame of reference, the floor is coming toward you at 9.8m/s². It appears that you are falling faster, which in fact you aren't if you attach yourself with an accelerometer.

So what you're saying is that when I jump out of an airplane, the earth suddenly begins to move towards me and the airplane suddenly starts to gain altitude even though the airplane's altimeter remains constant. 

So if the earth is continually moving upwards why don't the clouds just fall the earths surface, surely they too can't me moving upwards to as they're only bodies of condensation..

Quote from: Atom Man on March 31, 2009, 06:52:30 AM

Sorry Matrix but how you describe acceleration due to "gravity" has no logical reasoning. For the sake of the argument lets say g = +9.8 m/s^2 both at ground level and in the aircraft. How come g changes from 9.8 m/s^2 to 0 m/s^2 as soon as you step out?

An initial acceleration of of 9.8 m/s^2 to 0 m/s^2 at terminal velocity just seems far more logical. If a = 0 m/s^2 then you have 0 N force and would just float with the clouds since you will not be applying a force to displace the air.

v = u + at if u = 0 m/s and a = 0 m/s^2 then v = 0 m/s
and
F = ma if a = 0 m/s^2 then F = 0 N

Its using relativity. Lets say you are in a box with no windows. You take out an accelerometer. it says you are accelerating at 9.8 m/s^2. there is no way of knowing whether it is gravity or the box is accelerating to give you this reading. When you fall out of a plane and are in free fall lets say there is no air resistance. although it appears you are accelerating in the fourth dimension you are going in a constant speed.

Quote from: bgamelson on April 21, 2009, 04:18:45 PM

So what you're saying is that when I jump out of an airplane, the earth suddenly begins to move towards me and the airplane suddenly starts to gain altitude even though the airplane's altimeter remains constant. 

The airplane does not gain altitude; it just appears to be moving away from you.

Quote from: Matrix on April 19, 2009, 01:13:55 PM

Quote from: trig on April 17, 2009, 03:24:29 PM

Where, exactly did you find that "we have to know everything" principle?

Quote from: trig

But science has no place for "special cases" where some laws apply "on Earth" and others apply "off Earth"

Quote

I welcome the debate you say you want. Please show us the models you want to discuss and the predictions you can make based on the model, together with the experimental results on which you base your case for your model. But please, if you do not understand the scientific method, do not bother replying.

I am acquainted with the scientific method - that is why we have even gotten this far in this debate. FET has made predictions (such as the impossibility of sustained spaceflight), and it is those that we are here to debate and assess.

And your evidence is... what, exactly? You show that sustained spaceflight is impossible declaring that there is a conspiracy everywhere? Or that everyone that has seen a satellite with binoculars or telescopes is an idiot or conspirator?

There are several experiments that can be done, in accordance with the scientific method, and the "FE theorists" have been AWOL every time. Take, for example, the measurement of the azimuth of the Sun at dawn and dusk near the Equinox.

Tired old explanations are not experiments to verify or discredit a theory. Make an experiment that really can bring evidence to the claim that sustained space travel is not possible, or accept that nobody will ever accept that you are too lazy and poor to make and document your own observations of the satellites that have been orbiting Earth for the last decades.

Right, because I'm moving away from it.

 

The problem is, there is air resistance.  The airplane (let's say a DC-3 which I have jumped out of) is travelling at 120MPH when I jump.  I will immediately experience 120MPH air resistance and this resistance will prevent me from falling faster because airspeed vs. body weight/gravity is equal.  I will begin a slow arc towards the earth as gravity is upon me and within 12 seconds I will be falling towards earth at 120MPH. 

Now then, when I open my parachute, I slow down.  The earth does not change speed when I open my parachute.

Quote from: bgamelson on April 21, 2009, 04:27:49 PM

The problem is, there is air resistance.  The airplane (let's say a DC-3 which I have jumped out of) is travelling at 120MPH when I jump.  I will immediately experience 120MPH air resistance and this resistance will prevent me from falling faster because airspeed vs. body weight/gravity is equal.  I will begin a slow arc towards the earth as gravity is upon me and within 12 seconds I will be falling towards earth at 120MPH. 

Now then, when I open my parachute, I slow down.  The earth does not change speed when I open my parachute.

Neglecting air resistance, my accelerometer would read that I'm not accelerating while free-falling. In FE, the air will accelerate past me, exerting the drag force on me. I am now accelerating up by this drag force, which appears that I'm slowing down relative to a ground observer. Once my upward acceleration is equal to the upward acceleration of the Earth, I reach terminal velocity. In RE, same thing, I'm accelerating up due to drag force against this downward "force of gravity." I reach terminal velocity when the "force of gravity" equals to the drag force.

An accelerometer does not measure the '1g' of the Earth until you are at terminal velocity in either the RE or FE model. By definition free fall (without air resistance) is a relative state of rest (objects following geodesics), so if it could measure 'absolute acceleration' then you would have a means of figuring out the 'preferred rest frame' of the Universe, which is forbidden in relativity.

To clarify, an accelerometer would read (in the vertical axis, with '+' meaning 'upwards'):

1) stationary on the runway
 RE : +1g (9.81ms^-2) contact acceleration
 FE : +1a_UA (9.81ms^-2) contact acceleration

2) climbing to drop altitude
 RE : +1g + (vertical acceleration of aircraft)
 FE : +1a_UA + (vertical acceleration of aircraft)

3) level at drop alitutude
 RE : +1g - (small correction for altitude (g drops as 1/r² from surface of Earth))
 FE : +1a_UA - (small correction for altitude (source depends on your 'flavour' of FE))

4) the instant that Tom Bishop jumps out horizontally from the door
 RE : zero
 FE : zero

5) before reaching terminal velocity
 RE : zero + (air resistance as fall towards Earth at 1g acceleration [acceleration as measured from the ground])
 FE : zero + (air resistance as fall towards Earth at 1a_UA acceleration [acceleration as measured from the ground])

6) terminal velocity
 RE : +1g
 FE : +1a_UA

As you can see, the two are identical at all points. Neither accelerates faster than the other and neither 'feels' any different at any point (so long as you have a reasonable physical explanation for g dropping off with altitude, which FE provides a few alternative theories for). If I'm wrong at any point here, feel free to explain why.

When you say "accelerometer", I believe you're talking about a G meter that measures G forces.  If you are in freefall with no air resistance, the G meter would read 0.  This means you are accelerating due to the force of gravity pulling you down. 

When you reach a speed when air resistance counteracts your body weight being pulled by gravity, your acceleration stops and the G meter would now read 1. 

If you read the G meter while sitting on the ground, the G meter would read 1.  This is because gravity is causing your body to be pressed against the ground at a force of exactly 1g. 

You say:  "Once my upward acceleration is equal to the upward acceleration of the Earth, I reach terminal velocity."

Now just think about that for a minute.  You say both me and the earth are accelerating upward, however somehow those two forces are going to meet, and somehow nobody else on this earth feels this "acceleration" of the earth as they are standing there watching me jump out of the airplane.  Somehow the earth knows the precise moment when I jump so it can begin it's "acceleration" towards me as I "accelerate" away from it. 

WRONG!  The skydiver will always be moving towards the ground observer and the earth does not accelerate as the jumper exits the airplane. 

The jumper will only accelerate from whatever speed the airplane is moving to 120MPH and his direction of travel will change until he is travelling directly towards earth. The earth revolves.  God help us all if it begins to accelerate.

As usual, this subject has been debated before at some length, and as usual people can't be bothered to read the previous discussions.  I have been guilty of this in the past however, so in the interests of fairness please allow me to acquaint you with exactly why FET and RET are equivalent from the perspective of simple gravitation, with this quote from my formative years on this site:

Quote from: Matrix on September 01, 2008, 03:13:40 AM

An accelerometer does not measure the '1g' of the Earth until you are at terminal velocity in either the RE or FE model. By definition free fall (without air resistance) is a relative state of rest (objects following geodesics), so if it could measure 'absolute acceleration' then you would have a means of figuring out the 'preferred rest frame' of the Universe, which is forbidden in relativity.

To clarify, an accelerometer would read (in the vertical axis, with '+' meaning 'upwards'):

1) stationary on the runway
 RE : +1g (9.81ms^-2) contact acceleration
 FE : +1a_UA (9.81ms^-2) contact acceleration

2) climbing to drop altitude
 RE : +1g + (vertical acceleration of aircraft)
 FE : +1a_UA + (vertical acceleration of aircraft)

3) level at drop alitutude
 RE : +1g - (small correction for altitude (g drops as 1/r² from surface of Earth))
 FE : +1a_UA - (small correction for altitude (source depends on your 'flavour' of FE))

4) the instant that Tom Bishop jumps out horizontally from the door
 RE : zero
 FE : zero

5) before reaching terminal velocity
 RE : zero + (air resistance as fall towards Earth at 1g acceleration [acceleration as measured from the ground])
 FE : zero + (air resistance as fall towards Earth at 1a_UA acceleration [acceleration as measured from the ground])

6) terminal velocity
 RE : +1g
 FE : +1a_UA

As you can see, the two are identical at all points. Neither accelerates faster than the other and neither 'feels' any different at any point (so long as you have a reasonable physical explanation for g dropping off with altitude, which FE provides a few alternative theories for). If I'm wrong at any point here, feel free to explain why.

The jumper is not being accelerated by anything except by the force of drag from air resistance.