How Einstein's equivalence principle extends to the quantum world

August 17, 2018, University of Queensland
Credit: CC0 Public Domain

How Einstein's equivalence principle extends to the quantum world has been puzzling physicists for decades, but a team including a University of Queensland researcher has found the key to this question.

UQ physicist, Dr. Magdalena Zych from the ARC Centre of Excellence for Engineered Quantum Systems, and the University of Vienna's Professor Caslav Brukner have been working to discover if interact with gravity only through curved space-time.

"Einstein's contends that the total inertial and gravitational mass of any objects are equivalent, meaning all bodies fall in the same way when subject to gravity," Dr. Zych said.

"Physicists have been debating whether the principle applies to quantum , so to translate it to the we needed to find out how quantum particles interact with gravity.

"We realised that to do this we had to look at the mass."

Mass is dynamic quantity and can have different values, and in quantum physics, mass of a particle can be in a quantum 'superposition' of two different values.

According to the famous equation E=MC2, the mass of any object is held together by energy.

Quantum leap for Einstein's scientific principle
Artist's impression of quantum formulation. Credit: Australian Research Council Centre of Excellence for Engineered Quantum Systems (EQUS).

In a state unique to quantum physics, energy and mass can exist in a 'quantum superposition' – as if they consisted of two different values 'at the same time'.

"We realised that we had to look how particles in such quantum states of the mass behave in order to understand how a quantum particle sees gravity in general," she said.

"Our research found that for quantum particles in quantum superpositions of different masses, the principle implies additional restrictions that are not present for classical particles—this hadn't been discovered before.''

"It means that previous studies that attempted to translate the principle to physics were incomplete because they focused on trajectories of the particles but neglected the mass."

The study opens a door for new experiments that are necessary to test if obey the additional restrictions that have been found.

The study has been published in Nature Physics.

Explore further: UQ physicist builds on Einstein and Galileo's work

More information: Magdalena Zych et al. Quantum formulation of the Einstein equivalence principle, Nature Physics (2018). DOI: 10.1038/s41567-018-0197-6

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Bugsbunny67
1.4 / 5 (10) Aug 17, 2018
Who said that quantum superpositions are actually real? It would be easier to fuse GR with QM if there were no superpositions. The good thing is superpositions are not a prerequisite of QM but rather a weird interpretation.
antialias_physorg
4.3 / 5 (12) Aug 17, 2018
Who said that quantum superpositions are actually real?

Oh, I dunno...Like every double slit experiment, ever?
Mimath224
3.7 / 5 (3) Aug 17, 2018
Ha, for me I find the whole idea fascinating. Forgive me if I use non-quantum physics and imagine say, something like the Bohr Atom and the electron whizzing around the nucleus millions of times per second, how the hell does one check the equivalence principle on that. But I guess if I sat down long enough and understood the relevant equations sufficiently I'd probably find a way. Now extending to the modern atomic/sub-atomic quantum interpretations...yes well, I need articles like these to explain it to me. That's what makes me layman and others not so. But duality is no stranger to me and the seed of opposites is each opposite and if it is difficult to search for or in one then try the 'opposite' (basically what the researchers said in the final paragraphs). As I said, fascinating.
Bugsbunny67
1.7 / 5 (6) Aug 17, 2018
I am sorry but the superposition is not a verified fact, it is an interpretation of QM. It is never measured as a real superposition. It just demonstrates our lack of predictability. The rest is interpretation. The word superposition should be used carefully because it is only an interpretation and it should remain only an interpretation. Ask any good theoretical physicist. In Bohm-Debroglie interpretation, there are no such a thing as superpositions.
Gigel
5 / 5 (5) Aug 18, 2018
Free preprint, 3 years old though: https://arxiv.org...02.00971
Whart1984
Aug 18, 2018
This comment has been removed by a moderator.
Da Schneib
3 / 5 (3) Aug 18, 2018
Who said that quantum superpositions are actually real? It would be easier to fuse GR with QM if there were no superpositions. The good thing is superpositions are not a prerequisite of QM but rather a weird interpretation.
Ultimately superpositions come from Heisenberg uncertainty.

The most accurate measurements in all of science come from Heisenberg uncertainty. And the theory they confirm assumes superposition.
Whart1984
Aug 19, 2018
This comment has been removed by a moderator.
Mimath224
3.7 / 5 (3) Aug 19, 2018


The most accurate measurements in all of science come from Heisenberg uncertainty
It doesn't mean very much in science...Heisenberg uncertainty principle https://www.scirp...ID=68536 as any other physical principle...

Really, you think so? Going to violated here, Ha, you are in for some flak for certain!
antialias_physorg
3.4 / 5 (5) Aug 19, 2018
Heisenberg uncertainty principle can be violated as easily as any other physical principle.

This statement is technically true...because Uncertainty can't be violated (just like any other physical principle)
Whart1984
Aug 19, 2018
This comment has been removed by a moderator.
TorbjornLarsson
3 / 5 (6) Aug 19, 2018
I am not sure this result is much telling on current physics, since when they translate the Einstein Equivalence Principle to quantum physics operators, unsurprisingly the classical external EEP is preserved while the internal mass energies may not be. So they are arguing for experimental verification, which will tell us more about quantum physics but perhaps not on classical effects.

In general, in the weak field approximation they work in, a superposition of mass would be expected for the (approximate) quantum field theory of (linearized) general relativity, at a guess.

@What1984: Those references (at least the first one) are making aap's point.

State squeezing does not violate uncertainty principles, which is why the first link is titled that scientists "evade" it because it is still the operating constraint. Also, this is many years old physics I think, it was curious to first read about it but also "ah, so this is how uncertainty works (in this case)".
Whart1984
Aug 19, 2018
This comment has been removed by a moderator.
Captain Stumpy
3.5 / 5 (8) Aug 19, 2018
@zeph
The mainstream science evolved a circlejerking philosophy, which systematically evades all exceptions from established theories in a funny way: it simply gives them special name and from this moment it simply ignores them. That's all, really - no less, no more
blatantly false claim

1- just because you don't know what *is* being researched doesn't mean you know what is not being researched

2- strawman built on a false claim

3- your "illustration" doesn't support your strawman (See #1)

4- just because you can't get your pseudoscience legitimized because it's debunked ( https://www.natur...omms9174 ) doesn't mean mainstream science doesn't investigate or research legitimate science

5- your arguments for debunked pseudoscience is like going to a physics convention and asking why they don't validate the bible as legitimate science because of the Ark model build by Hamm as it's obviously built and it doesn't leak when it rains
Bugsbunny67
1 / 5 (1) Aug 19, 2018
After having read the Arxiv article, I understand that they try to integrate the multiple possible paths given by QM probabilities to be able to test EEP at particles scale. It does not implies true superpositions. But still, my earlier comments are right. Do your homework before down voting... QM mathematics does not imply superpositions, it implies multiple possibilities which we are unable to predict. One interpretation of this is that all the probabilities represent the reality and that reality exists as superpositions until it is measured or until it interacts with another set of particles. But it is just an interpretation because what is measured is always only one specific path. You can't measure superpositions, it is forbidden by QM mathematics. Maybe it is because there is no such a thing and we need another interpretation. The problem of using the word superposition is that it can be misinterpreted as a necessary part of reality and people stop looking for better solutions.
Da Schneib
4 / 5 (4) Aug 19, 2018
The question here is how gravity operates on the uncertain mass. Remember also that gravity acts on energy. This is a confirmation of GRT.
savvys84
1 / 5 (4) Aug 20, 2018
The question here is how gravity operates on the uncertain mass. Remember also that gravity acts on energy. This is a confirmation of GRT.


The question here is how gravity operates on the uncertain mass. Remember also that gravity acts on energy. This is a confirmation of GRT.

Oh really? GRT is bollox
Captain Skip
1 / 5 (2) Aug 20, 2018
Mass is not a property it is an effect. You need either acceleration or gravity to measure mass. there fore it is more like inductance than length or color.
This actually is another situation that proves that GRT is a bad sequel. The gravitational constant and the so called curvature of space-time is utter bunk.

Long Live Hubble
knowphiself
not rated yet Aug 20, 2018
mass is a relativistic moment , gravity is an effect .

:. what is the relationship to the blackbody effect and time?
Pt_ of Interest
not rated yet Aug 21, 2018
I am sorry but the superposition is not a verified fact, it is an interpretation of QM. It is never measured as a real superposition. It just demonstrates our lack of predictability. The rest is interpretation. The word superposition should be used carefully because it is only an interpretation and it should remain only an interpretation. Ask any good theoretical physicist. In Bohm-Debroglie interpretation, there are no such a thing as superpositions.


I believe that one would be very hard pressed to explain the success of at least the 7-BIT Caltech quantum computer experiment in 2004 without it, among other things. It would be like saying that the digits on your calculator were stuck at a certain random digits whenever you turned on your calculator, only pressing the equal sign sent power to them, so that those states would be revealed. However, they "just happened" to be the answer to the arithmetic problem you keyed in. -- Not very likely...
Pt_ of Interest
1 / 5 (1) Aug 21, 2018
One thing very interesting here is the implications for the Penrose-Hameroff orchestrated objective reduction theory of quantum collapse due to spacetime curvature at approximately the quantum (graviton) level.

Off-hand, pit would seem that the greater mass possibility will win and as there is no interaction with spacetime prior to the onset of collapse, the mass of the quantum particle will at least generally be equal to that of the largest possible mass.
savvys84
1 / 5 (3) Aug 21, 2018
Mass is not a property it is an effect. You need either acceleration or gravity to measure mass. there fore it is more like inductance than length or color.
This actually is another situation that proves that GRT is a bad sequel. The gravitational constant and the so called curvature of space-time is utter bunk.

Long Live Hubble

Quite right there, mate
Whart1984
Aug 21, 2018
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Whart1984
Aug 21, 2018
This comment has been removed by a moderator.
Whart1984
Aug 21, 2018
This comment has been removed by a moderator.
Whart1984
Aug 21, 2018
This comment has been removed by a moderator.
Whart1984
Aug 21, 2018
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tallenglish
1 / 5 (1) Aug 24, 2018
Here is an idea, it is an expansion on special relativity and as well as concepts of past, now and future for time we also have outside, here, inside. Outside is the realm of E/M and inside is the realm of strong and weak forces. So while we think of E/M as expanding spacetime, mass curls it up in a ball. As you can see E/M are at right angles as we know, as is strong and weak forces. Matter and dark matter are the same stuff but curve spacetime in mutually opposite ways (so M & DM repel but DM-DM attracts just as M-M attracts).

Now the cool bit explains why gravity is emergent, as light expands spacetime, mass knots it up, so at the big bang there was no mass, then it became 1D, then 2D, 3D, etc. as it did that gravity becomes stronger and light reduces momentum - eventually we will get to a state where its all mass and 0Hz light and the process will reverse.

https://drive.goo...q0U/view
savvys84
not rated yet Aug 25, 2018
@tallenglish
thats kind of nutty for sure
humy
3 / 5 (2) Aug 25, 2018
In dense aether model the quantum mechanics and relativity are closely related each other. For example, when the particle moves, it makes a wake wave of vacuum around itself in similar way, like the boat floating at the water surface - so called pilot wave. .
Whart1984

PLEASE Explain to us in your own words exactly what YOU personally think "dense aether mode" IS.
Please provide us with a (ANY) specific weblink explaining what IS "dense aether mode" and also provide us with a (ANY) specific weblink (the same one or any different one will do) that also explains how it relates to relativity in the way YOU think it does....
If you only just try and do this (shouldn't be difficult if what you say isn't bull****), I believe you might learn something new.

Whart1984
Aug 25, 2018
This comment has been removed by a moderator.
Whart1984
Aug 25, 2018
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humy
4 / 5 (4) Aug 25, 2018
PLEASE Explain .. in your own words .. what YOU .. think "dense aether mode" IS.


Many physicists started to say recently, that gravity or quantum mechanics or space-time... is EMERGENT. Please explain .. in your own words, what they actually have on mind. Why it is so widespread concept and trend in contemporary physics?
Whart

Why do you want me to suddenly waste my time and change the subject completely to something totally irrelevant to what you were saying ("dense aether mode")?
OBVIOUSLY, its because you have absolutely NO IDEA what you mean by "dense aether mode". Why else? You are obviously just being evasive and you fool nobody here.
Your two links don't even merely mention "aether" let alone "dense aether mode"; which confirms you don't know what you are talking about.
+ the "dense aether mode", whatever that is supposed to mean, clearly is NOT a "widespread concept and trend in contemporary physics". It is just some CRAP you made up.
humy
3.7 / 5 (3) Aug 25, 2018
My apologies; I kept saying "dense aether mode" when I meant "dense aether model".
But, no matter, it is still just some made up CRAP either way.
Captain Stumpy
3.7 / 5 (3) Aug 25, 2018
@humy
OBVIOUSLY, its because you have absolutely NO IDEA what you mean by "dense aether mode"
no one else knows WTF he means either, especially in light of the fact that aether is proven to be false - https://www.natur...omms9174

+ the "dense aether mode", whatever that is supposed to mean, clearly is NOT a "widespread concept and trend in contemporary physics". It is just some CRAP you made up
yep

and a word of caution: do not, under any circumstances, go to any reddit link he sends with "AWT" in the link

I would also suggest not going to any shortened link

the "journal" links he may provide are his attempts to link the pseudoscience with a credible science because he actually believes that his aether model is legit and can be justified by comparing his beliefs he states with the science
granville583762
5 / 5 (2) Sep 03, 2018
Einstein's equivalence principle contends that the total inertial and gravitational mass of any objects are equivalent, meaning all bodies fall in the same way when subject to gravity
with this einsteinion fact it is known a mass falling 1metre and 1m+1femyo-metre can be calculated with the same accuracy as can a mass falling 1 femto-metre be calculate with Newton's law of gravity, as the quantum world starts at 1nano-metre Einstein's equivalence principle holds at any dimension
Mimath224
not rated yet Sep 03, 2018
@humy
OBVIOUSLY....NO IDEA what you mean by "dense aether mode"
no one else knows WTF he means either, especially in light of the fact that aether is proven to be false - https://www.natur...omms9174
+ the "dense aether mode", whatever that is supposed to mean, clearly is NOT a "widespread concept and trend in contemporary physics". It is just some CRAP you made up
yep
and a word of caution:.... any reddit link he sends with "AWT" in the link
I would also suggest not going to any shortened link
the "journal" links he may provide are his at

I am not AWT supporter but I do purchase books on alternative theories just to see for myself why this & that. Buying several Aether model books among them two by Steven Rado. In one (kinematics) he talks of the finding the Aether density (via Aetherons) and later gives a 'bulk modulus'. This, or something like it, is probably the origin of the term 'dense Aether Model' Just a thought, that's all.

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