Do scientists admit they don't know the explanation for gravitation?

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rabinoz

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It's not quite that "scientists admit they don't know" but rather that scientists cannot find a quantum mechanical explanation for gravitation without "holes in it".

And there are excellent reasons why "they don't know".
Einstein recognised that "Newton's theory works extraordinarily well for the weak, static gravitational fields of our solar system".
And that is all that is needed in anything we need on earth or even in the solar system, unless the velocity or needed precision are extraordinary.

See this reference where GR is required to "return Newtonian results for ordinary conditions".
Quote from: John D. Norton
Einstein's Pathway to General Relativity, Assembling the Pieces: The "Entwurf" Paper of 1913, Einstein's Pathway to General Relativity, John D. Norton
This quantity is almost the Einstein tensor. Grossmann is so close to the modern Einstein field equations that one could now scarcely imagine how the final steps could not be taken.

But they are not taken. One condition the new equations must satisfy is that they must return Newtonian results for ordinary conditions.
For Newton's theory works extraordinarily well for the weak, static gravitational fields of our solar system. The sentence highlighted in red says:

"However it turns out that this tensor does not reduce to the [Newtonian expression] Δφ in the case of infinitely weak, static gravitational fields."
That is, Grossmann declared the equations under consideration not to merge nicely back into Newton's theory in this essential case.
Einstein's General Relativity is an excellent explanation of gravitation but it is a "classical theory" but there are reason's that indicate that gravitation should also be quantised.

Quantum theory has "force carriers" for the other fundamental forces, for example, the "photon" is the "force carrier" for "electromagnetic forces".
By analogy many of the properties of the "graviton" can by hypothesised but:
  • Some of these properties lead to severe inconsistencies and
  • On an atomic scale gravitation is some 1040 times weaker than the electromagnetic force.
    Hence the energy of a graviton is far less than that of a photon and hence the graviton (even if it exists) might never be individually detected.
Here is an introductory video on quantum gravity:
Quote from: Dr. Don Lincoln

Quantum Gravity, Fermilab
While there are many challenges facing modern particle physics, perhaps the ultimate one (and certainly among the most difficult) is to describe the nature of gravity in the quantum realm.  Despite a century of effort, scientists have had only the most cursory of success.  In this video, Fermilab’s Dr. Don Lincoln talks about the idea of quantum gravity and sketches out the need for this difficult advance.

General Relativity provides an explanation of gravitation but it does not fit with quantum theory.

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boydster

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Re: Do scientists admit they don't know the explanation for gravitation?
« Reply #1 on: March 08, 2019, 08:49:51 PM »
I think scientists are pretty clear that they don't know the underlying cause of gravitation. They haven't been able to find the boson. That's a problem. It's apparently a force, and a fundamental one at that, and we have a theoretical graviton that makes an appearance in many hypotheses and also has a honorable mention in versions of string theory, but it remains as yet undetected. And many a devoted theoretical physicist has tried finding a way to connect it with the rest of the fundamental forces in vain.

On one hand, it's easy to say it's just mass warping space. But that doesn't seem to fill in all the spaces on this paint by number picture. The outside of galaxies spin too fast. Or matter is missing. Or there is some vital information missing.

If it's truly a fundamental force, as it seems, the force carrier particle is hiding from us and so we can't explain gravity. If it's not a fundamental force, but an emergent property, we really have missed the mark and so we can't explain gravity. We can explain the effect, and we can find correlating properties, but the cause remains a bit elusive.
Let me explain this in a way you can understand. What you just wrote sounds exactly like something that a gay rights Portuguese Samurai would write.

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rabinoz

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Re: Do scientists admit they don't know the explanation for gravitation?
« Reply #2 on: March 08, 2019, 10:32:18 PM »
I think scientists are pretty clear that they don't know the underlying cause of gravitation. They haven't been able to find the boson.
And it is possible that they never will directly observe "the boson", the graviton, because as hypothesised at present it would have such an incredibly small energy.

Quote from: boydster
That's a problem. It's apparently a force, and a fundamental one at that, and we have a theoretical graviton that makes an appearance in many hypotheses and also has a honorable mention in versions of string theory, but it remains as yet undetected. And many a devoted theoretical physicist has tried finding a way to connect it with the rest of the fundamental forces in vain.
That is only a problem when attempting to make a theory of quantised gravitation.
Though GR does lead to a singularity inside a black hole and that cannot be observed so a resolution might be difficult.
Gravitation must be quantised at the sub atomic level or sub-atomic particles, even a hydrogen atom, would emit gravitational waves.

Quote from: boydster
On one hand, it's easy to say it's just mass warping space. But that doesn't seem to fill in all the spaces on this paint by number picture. The outside of galaxies spin too fast. Or matter is missing. Or there is some vital information missing.
There is every reason to believe that it might by matter missing, even from another dimension, because GR seems to pass all the tests so far.
Or, as you say, "there is some vital information missing".

Quote from: boydster
If it's truly a fundamental force, as it seems, the force carrier particle is hiding from us and so we can't explain gravity. If it's not a fundamental force, but an emergent property, we really have missed the mark and so we can't explain gravity. We can explain the effect, and we can find correlating properties, but the cause remains a bit elusive.
And that "force carrier particle" might be "hiding from us" in plain sight simply it is too "small" to observe.

Sure, there are unknowns but scientists understand very accurately how gravitation behaves.
Nevertheless they are looking very hard to find anomalies at both ends of the scale that might give clues about these unknowns.

The problem is, many claim that because these "scientists" don't know all the answers about gravitation that it must be a "untrue".

So earn yourself a Nobel Prize and prove where GR is wrong - plenty are trying to.

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boydster

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Re: Do scientists admit they don't know the explanation for gravitation?
« Reply #3 on: March 08, 2019, 11:00:48 PM »
I am beside myself that you would say "it might by matter missing, even from another dimension." There is absolutely no physical evidence of extra dimensions at this point outside of pretty tenuous theoretical frameworks. It's a black box. "Magic happens here," if you will. To appeal to extra dimensions when no evidence is really on the table while deriding FEers for a similar transgression is an interesting tactic. I don't disagree that all the facts aren't in, but you can't claim that territory only for RE and disallow it for FE.

I don't see many people arguing that the force we feel at the surface of the Earth is fake. Several people here argue about the underlying cause and characteristics, and I think that's to be expected at a place like FES. It's a feature, not a bug. And more often than not, it's the FE here that get derided, even by those who have enough knowledge to put aside their beliefs to say "What if?" and try to pursue the thought experiment.
Let me explain this in a way you can understand. What you just wrote sounds exactly like something that a gay rights Portuguese Samurai would write.

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rabinoz

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Re: Do scientists admit they don't know the explanation for gravitation?
« Reply #4 on: March 09, 2019, 12:20:42 AM »
I am beside myself that you would say "it might by matter missing, even from another dimension." There is absolutely no physical evidence of extra dimensions at this point outside of pretty tenuous theoretical frameworks. It's a black box. "Magic happens here," if you will. To appeal to extra dimensions when no evidence is really on the table while deriding FEers for a similar transgression is an interesting tactic.
I'm so glad to be a source of innocent merriment but I can't claim any credit. I'm no Cosmologist, I just look at the pretty pictures ;D.

Michio Kaku: What Is Dark Matter?
Big Think
     
The LHC, dark matter and extra dimensions.
Pindex
     
Could dark matter be coming from other dimensions?
World Science U
Quote from: boydster
I don't disagree that all the facts aren't in, but you can't claim that territory only for RE and disallow it for FE.
There is a huge difference.
Whatever dark matter might be it is completely insignificant in our neighborhood of space.
And dark energy, whether it is necessary or not, has no effect on objects gravitationally bound and that includes all the galaxies in our super-group.
So these hypotheses are for regions of space that can only be observed very indirectly.
But the things claimed by the various FE hypotheses are for regions that can be comparatively easily observed and even visited, but they deny that.

So I see no double standard in using, as yet, unproven hypotheses to explain these observations from far far away - millions of light years in some cases while not accepting flat earthers denial of the behaviour of gravitation.
Especially as this behaviour of gravitation has been verified by many experiments on earth and astronomical measurements.

But flat-earthers simply deny all this and claim that all these experiments and the many more qualitative demonstrations are fakes.

Quote from: boydster
I don't see many people arguing that the force we feel at the surface of the Earth is fake. Several people here argue about the underlying cause and characteristics, and I think that's to be expected at a place like FES.
It's fine to debate the underlying cause but to deny the measured characteristics without evidence seems quite disingenuous to me.

Quote from: boydster
It's a feature, not a bug. And more often than not, it's the FE here that get derided, even by those who have enough knowledge to put aside their beliefs to say "What if?" and try to pursue the thought experiment.
Within our whole solar system even Newtonian Gravitation is accurate to a degree no flat earther seems able to measure.
And the minute variations near the sun are fit very with General Relativity.

But no flat earth "model" seems able to function if the Newtonian Laws are correct.
Few flat earthers, if any, accept that gravitation behaves as if mass attracts mass as .
The "infinite plane earth" is almost consistent with it except that it provides no feasible explanation for the the motion of sun, moon, planets and stars.

Then UA gives a reasonable simulation of a uniform gravitational field across the whole earth.
It tries, however, to explain the variations observed by postulating "celestial gravitation" but the justification of UA is Einstein's Equivalence Principle.
The Equivalence Principle states that inertial mass is identical to the gravitational mass but "celestial gravitation" would demand that "celestial objects" must be composed of a different type of matter.
But there is no evidence yet of any "different type of matter" (dark matter ;D).

On of the biggest problems I have with any flat earth "theory" is that all contrary evidence seems able to be claimed as "fabricated" making said flat earth "theory" unfalsifiable.

Re: Do scientists admit they don't know the explanation for gravitation?
« Reply #5 on: March 09, 2019, 01:45:56 AM »
I am beside myself that you would say "it might by matter missing, even from another dimension." There is absolutely no physical evidence of extra dimensions at this point outside of pretty tenuous theoretical frameworks. It's a black box. "Magic happens here," if you will. To appeal to extra dimensions when no evidence is really on the table while deriding FEers for a similar transgression is an interesting tactic. I don't disagree that all the facts aren't in, but you can't claim that territory only for RE and disallow it for FE.

I don't see many people arguing that the force we feel at the surface of the Earth is fake. Several people here argue about the underlying cause and characteristics, and I think that's to be expected at a place like FES. It's a feature, not a bug. And more often than not, it's the FE here that get derided, even by those who have enough knowledge to put aside their beliefs to say "What if?" and try to pursue the thought experiment.

All what you say may be true, but for one moment turn your scientific spotlight away from gravity on to some aspect of flat earth belief with the same intensity, such as the sun for example. Now what do you see? What of those ideas? Do they stand  up to even the slightest scrutiny?

While it may we’ll be the case that the absolute fundamentals of gravity remain for the moment a mystery that does not for one moment give any credence to UA or any other piece of flat earth mumbo jumbo. While some aspects of gravity do remain unknown, the effect gravity has is very well understood. This understanding is what allows precise calculations to be made to plot the course of the many spacecraft that have been launched over the years. It also enables theories to be confirmed as in the case of LIGO and gravitational waves. The fact that some flat earth idiots refuse to believe in the  existance of such things is their problem.

The only reason you have been able to regurgitate any science at all is because of the work and discoveries of scientists, none of which would subscribe to any of your whacky FE beliefs. Being that there is no such thing as a flat earth scientist or flat earth scientific research all the beliefs of the flat earth community have emerged based on nothing more than random made up nonesense. Trying to poke holes in conventional science by pointing out the minuscule holes in gravitational theory while ignoring the massive planet sized gaps in all your flat earth made up nonsense is disingenuous to say the least.


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boydster

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Re: Do scientists admit they don't know the explanation for gravitation?
« Reply #6 on: March 09, 2019, 04:22:50 AM »
You really are dumber than a bag of hammers, lonegranger. Stop making assumptions.

But that aside, this is in fact a Flat Earth forum. This is a place where Flat Earthers are meant to be able to discuss their ideas and work through the challenges that come up to better refine them or decide to move in a different direction. Yet too often, aggressive REers argue vocally and disingenuously in some attempt to simply shut down conversation. And frequently, it's over parts of science that they have less awareness about than the FEers they are arguing with. See: literally every thread started by some n00mtm that thinks UA would result in the Earth exceeding c. Why bother coming here simply to belittle and insult, when you could engage in a thought experiment instead (If flat, then how)?


The n00mtm logo is the intellectual property of Bullwinkle and had been used here without his express content
Let me explain this in a way you can understand. What you just wrote sounds exactly like something that a gay rights Portuguese Samurai would write.