Final Results of the MICROSCOPE Mission Confirms Einstein's Equivalence Principle (presse.cnes.fr) 28
Long-time Slashdot reader orsayman writes: Remember the MICROSCOPE satellite ? In 2017, based on its first results, scientists were able to confirm Einstein's equivalence principle (a key assumption in General Relativity) to unprecedented precision.
Recently, they were able to improve precision by almost another order of magnitude by using all the data. Fortunately (or not) no violation of the principle was detected which could help physicists to improve their theories of quantum gravity.
Apparently the team expects to send a new mission "in the second half of the 2030s" aiming for another huge improvement in precision.
Recently, they were able to improve precision by almost another order of magnitude by using all the data. Fortunately (or not) no violation of the principle was detected which could help physicists to improve their theories of quantum gravity.
Apparently the team expects to send a new mission "in the second half of the 2030s" aiming for another huge improvement in precision.
A natural (Score:2)
Little Al rolls a natural again.
Re:A new mission in the 2030's to improve more (Score:5, Insightful)
At what point do we stop pissing away billions of dollars on this ...?
Who is "we"? Unless you're a French taxpayer, it isn't your money.
This mission cost way less than $1B. It was a mini-satellite designed with standardized components and launched along with other mini and micro (Cubesat) satellites to keep costs down.
and call it good
Look, do you want Warp drives and FTL travel? The equivalence principle makes those impossible. So we have to look for a flaw or loophole if we want to colonize the galaxy. The only other alternative is generation ships.
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Look, do you want Warp drives and FTL travel?
Huh? Explain yourself.
The equivalence principle may make those mathematically possible, but it's also responsible for making them physically impossible, to the best of our knowledge.
Not that I agree with the person you're rebuking in the slightest.
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it's also responsible for making them physically impossible, to the best of our knowledge.
Ummm. Yes. That's what I said.
I was hoping to retire someday to a small cabbage farm on a terraformed planet orbiting Proxima Centauri B, but alas, that is looking more and more unlikely.
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I misread "impossible" as "possible".
My apologies.
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Right, all science worth sciencing has been scienced by now. If Jesus was still the king of France, He would've spent the money on bombs.
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In addition to normal neutrons, protons and electrons, matter contains a lot of virtual particles that interact gravitationally. In the Einstein model where space is curved it makes sense that everything falls at EXACTLY the same rate, but that is much harder to explain in any other type of model. But the Einstein model is not easily compatible with quantum mechanics.
So this type of experiment is a window on quantum gravity, which is not yet understood..
Re:A new mission in the 2030's to improve more (Score:4, Informative)
matter contains a lot of virtual particles that interact gravitationally.
No- that's the problem. They can't interact gravitationally without breaking major conservation laws. But the equivalence principle says they must.
But the Einstein model is not easily compatible with quantum mechanics.
Unfortunately, it's completely incompatible.
Unfortunately further, evidence for both is overwhelmingly strong.
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Quantum mechanics and general relativity aren't "completely incompatible." It's boringly straightforward to make an effective quantum gravity theory that works almost up to the Planck energy. The two are indeed incompatible after that.
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Quantum mechanics and general relativity aren't "completely incompatible."
Yes, they absolutely are.
GR cannot suffer quantized spacetime.
And indeed, all attempts at making a theory of quantum gravity that reduces to GR in the semiclassical limit has failed.
This includes what I assume you're referring to- LQG, which simply ignores the problems, and fails by definition.
It's boringly straightforward to make an effective quantum gravity theory that works almost up to the Planck energy.
All attempts at making a theory of quantum gravity that reduces to GR in the semiclassical limit has failed.
This includes what I assume you're referring to- LQG, which simply ignores the problems, and fails by def
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The problem is time. We invented time to help us explain the universe that we perceieve. Time isn't an innate property of the universe like 3D space and mass are. But what about SpaceTime? Just because we have a theory about how the universe works and call it SpaceTime doesn't mean that the "time" part of that actually exists. You can't give me a cup of time. Maybe when we have another way of explaining the universe that doesn't involve time we'll realise our mistake.
The problem is that all attempts at formulating a theory that describes how the macroscale universe works that doesn't include a continuous spacetime all fail to reproduce basic general relativity.
Put another way, "all available evidence to the contrary".
This isn't to disagree with you, by any means.
How do we explain the universe without time? I don't know. If I did, I'd probably have a Nobel prize or two.
Yup.
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Well, no, time and space seem to be the same stuff and both seem to emerge from some currently unknown fundamental property. Understand what they emerge from and you understand the lot.
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Well, you are very confident in your opinion.
This might interest you:
http://www.scholarpedia.org/ar... [scholarpedia.org]
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What it allows for is applying GR to QM calculations by ignoring the fact that they're incompatible. I.e., throw away lorentz invariance and the WEP, and "tada!", "they're compatible!"
Which is of course nonsense, because what you have then is no longer GR.
That is not compatibility.
A better formulation of your claim would be: "you can take snapshots of GR and apply them to QM, while we look for a renormalizable theory of QG in the meantime"
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An effective theory is precisely what I described: a theory that works just fine up to an energy bound. In this case, it's pretty close to the Planck energy.
It's pretty strange to say QFT and GR are incompatible because their combination is an effective theory when GR itself is an effective theory which breaks down... around the Planck length.
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An effective theory is precisely what I described: a theory that works just fine up to an energy bound. In this case, it's pretty close to the Planck energy.
An effective theory.
You can make an effective theory of anything.
It's pretty strange to say QFT and GR are incompatible because their combination is an effective theory when GR itself is an effective theory which breaks down... around the Planck length.
GR is not an effective theory in the slightest. Nor does it "break down" at the Planck length.
Sure, you can argue that "all theories are effective theories, maaaaan", but I consider that nothing more than a gesture of bad faith.
I don't get where you're pulling the "compatibility" from. "Able to replicate the results of, up to a certain scale" does not imply compatibility.
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The way I see it, we have only just discovered the Higgs Boson (TM). There are much, much, much, much, much heavier bosons out there, but we can't even fathom the amount of energy it would take to discover them... So we settled for one we could. Might as well call them Black Holes at this point. You know they're t
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This.
How far do we have to go to satisfy ourselves that A=B? Now, if someone has a quantum gravity theory that says there should be an X ppm difference, then let's look for it. If no difference is found given that level of accuracy, then that theory is invalid. Job done.
On the other hand, if a new theory is proposed that suggests a smaller difference (Y parts per billion, for example), then we have a reason to look again. Otherwise, no.
Skeptical of result (Score:2)
Why? (Score:2)
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If there's an exception, there's an application.