Slashdot Mirror
Entanglement Makes Quantum Particles Measurably Heavier, Says Quantum Theorist
KentuckyFC writes: Physicists have long hoped to unify the two great theories of the 20th century: general relativity and quantum mechanics. And yet a workable theory of quantum gravity is as far away as ever. Now one theorist has discovered that the uniquely quantum property of entanglement does indeed influence a gravitational field and this could pave the way for the first experimental observation of a quantum gravity phenomenon. The discovery is based on the long-known quantum phenomenon in which a single particle can be in two places at the same time. These locations then become entangled — in other words they share the same quantum existence. While formulating this phenomenon within the framework of general relativity, the physicist showed that if the entanglement is tuned in a precise way, it should influence the local gravitational field. In other words, the particle should seem heavier. The effect for a single electron-sized particle is tiny — about one part in 10^37. But it may be possible to magnify the effect using heavier particles, ultrarelativistic particles or even several particles that are already entangled.
Sure we can.... Light years....
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
please add a disclaimer that the content is served using medium.
We only need to measure the mass of a 9.10938291 × 10^-31 kilogram particle accurate to 1 part in 10^-37. Alternatively, we can speed the electron up to 0.999c so it weighs more, then entangle it, and then measure it's mass to 1 part in 10^-37, with less than 5 sigma of measurement error.
Either way, I should have it done by lunch time.
No, really. We cannot measure anything to 37 decimal places. Not even close. If you measure the speed of light there will be uncertainty. If you insist the speed of light is exact by definition, then the uncertainty is in the length of a meter or the duration of a second or both.
Doc said I'm gaining weight. Now I know that I am just entangled. I will cancel my diet.
Yo mama's so fat her wave function collapses into multiple eigenstates.
X
As anyone who has been to weight watchers knows, of course you can measure 10^-37. Different underwear. Poop before going. Disentangle yourself from the universe...
So what is going to be the Next Big Thing?
What is the next Theory of Relativity waiting to be solved and what will be the game changing technology made possible by it?
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
Sure we can.... Light years....
No, we can't. Think about it for a second ;-)
An increase in rest mass? Added momentum/energy?
I wish I could find somewhere that talked about physics without dumbing it down to the point that there's no actual information. I've yet to see anything about entanglement that isn't pop science nonsense, and it leads me to see it in the same light Einstein did - horse shit.
The size of the visible universe is only on the order of 10^9 light years, so that won't do it. But combine it with the range of the weak force, which has been measured and our direct measurement capability spans a range of about 10^39 (weak force ~= 10^-18 meters, lightyear ~= 10^12 meters, visible universe ~= 10^9 lightyears) so we can at least comprehend this number in a concrete way. Measuring it even indirectly... not going to happen with your basic bathroom scale. But we are talking about finding a way to relate effects on the Planck scale to the cosmogical scale so big exponents should be unsurprising. Unlike the outspoken AC above I will wait for peer review before adjusting my bullshit meter. Naturally, we all want to believe there is some big breakthrough here after the endless low calorie diet of contrived mathematical attempts to unify the big theories for the last too many decades. Is this one it? Seems unlikely just based on the long run of failed attempts. But I will just sit back with popcorn and enjoy the show. At worst, a refreshing break from the usual multidimensional mathematical salad parade. I'm particularly interested in more eplanation of how two entangled particles became one, at least according to the press.
When all you have is a hammer, every problem starts to look like a thumb.
I thought experiments in neutron interferometry already established gravitation influence upon quantum mechanical observations...
That's a theoretical analysis, not an experimental measurement, and is likely to be particularly dubious since we don't have a working theory for quantized general relativity yet. Interesting, but the phrase "does indeed" in the summary is a significant overstatement.
This sounds a lot like Penrose's proposal for wavefunction collapse caused by gravitational disturbance caused by particles being in a superposition of two locations...
We can't measure anything using any instrument anywhere to a precision of 1/10^37th. Bullshit meter is off the charts
We can't make any single measurement which contains 37 digits and have each of those digits accurate, that's true.
Just out of curiosity, how do radios work? I'm told that the measurement units for an antenna nanovolts per meter. Does the receiver make a 12-volt measurement to 8 digits of accuracy in order to recover the signal?
Or does the receiver amplify the signal so that it's large enough to be readily detected?
And is there no way to make multiple measurements so that the effect adds up? Can we do a million measurements added together to make the signal a million times stronger?
Seeing as you are talking about a change in mass that is 34 orders of magnitude smaller than the Planck constant
h/2 > (delta MV)(Delta x)
(6.62606957 × 10-34 m2 kg / s)/2 > (Delta (M)*V)(Delta x)
delta M = 9.10938215kg×(10^-31)/ 10^37
or = 9.10938215kg×(10^-68)
We are looking at some pretty big uncertainty about where the particle is and how fast it's moving.
The current uncertainty of electron rest mass is
http://en.wikipedia.org/wiki/E...
The 2006 CODATA recommended value has a relative uncertainty of 4.2×1010
So all you need to do is add 27 orders of magnitude to the certainty of the electrons mass.
[...]Either way, I should have it done by lunch time.
I see you've read the article, so can you explain something for me?
I'm told that photons gain energy when falling into a black hole. Suppose you have two entangled photons and one goes off and gets captured by a black hole.
Based on the article, would there be any noticeable effect on the other entangled photon?
Yes, you can measure anything to any number of digits. After the last significant digit you can just start making them up. Because when someone is talking about how many digits they measure to, they are talking about significant digits. Yes, it's a short hand, but a well understood one.
Minor error in googling. There's probably closer to 7.4x10^79 atoms at a minimum (extrapolated from the initial #, which is visible mass, taken to be hydrogen, then multiplied by .74 to get just the hypothetical hydrogen atoms).
This only shores up my point that 37 decimal places is not all that astounding given the proper units. Context matters. A blanket statement that "we cannot measure to 37 decimal places" is as useless as a measurement with no figure for error and no units given.
Given that two particles can emitted by a single source entangled, sent a long distance apart, and remain entangled,
And that if one particle becomes disentangled the other particle instantaneously becomes disentangled,
If we can measure the entanglement of a particle by its mass,
Then we can communicate faster than light.
But the no-communication theorem states that, during measurement of an entangled quantum state, it is not possible for one observer, by making a measurement of a subsystem of the total state, to communicate information to another observer.
So I think this means that either the no-communication theorem is wrong, or the change in mass of an entangled particle cannot be measured.
(T>t && O(n)--) == sqrt(666)
http://en.wikipedia.org/wiki/Penrose_interpretation
What is with slashdot and the exponentiation symbol\
Only one of the meter or the second can be independently uncertain. The speed of light in a vaccuum, whatever it is, is exact and therefore we say it exactly relates 299972458 meters to one second, with the smallest uncertainty originating from the measurement of time's passage.
The uncertainty limits are set by resonance bandwidths of the transitions measured by atomic clocks (There is no "time-energy" uncertainty relation, because time is not an operator that can fail to commute). Cesium has been pushed down to a relative uncertainty of 10^-14sec/sec; Because the frequency is so much higher, aluminum ion clocks can acheive uncertainties around of 10^-17.
However this only applies to direct measurement: A cesium clock's output frequency is stable enough that the GR-induced change in frequency due to raising it one meter higher, for example, is directly measurable because that change is larger than the random wander. But if you know what you're looking for, there are other techniques to extract a signal from far below the noise floor (c.f. lockin amplifier / synchronous demodulator) or ways to derive side-effects which provide a better SNR in the first place (e.g. a Higgs itself will never be directly observed, but the LHC picks up plenty double-photon or 4-lepton events)
It seems to me that one way to state this information is that mass can be a variable according to circumstances. And that screws the pooch. Are we entering an era in which every term in an equation is a variable? Can mathematics tolerate multiple variables within an equation? And if so to what degree can variables be the elememts of an equation and yield any useful solutions?
FWIW, it appears from the paper that this extra "mass" is an artifact of analyzing entangled particles in a linearized gravity framework and observing a stress-energy tensor term that seems to appear higher for entangled particles and radiated away as particles move to decoherence. This perhaps might be considered the mass of the entanglement.
On the other hand, wouldn't it be cool if the reason for the observed equivalency of gravitational mass and inertial mass was somehow related to quantum entanglement? (yes I know this is unrelated to this phenomena, but still)...
One part in 10^37 is not measurably heavier. No measurement in science has anything like 37 significant figures*.
*No, the cosmological constant does not count, as it was not measured from quantum principles, but from cosmological ones.
I'm not fat, I'm quantum entangled!
The discovery is based on the long-known quantum phenomenon in which a single particle can be in two places at the same time.
Wrooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong.
If an entangled particle becomes disentangled and loses that extra weight, how long before it gains all of it's weight back?
This would explain a lot of things!
We can use dehydration, laxatives, acceleration to near the speed of light and carb restriction on this particle and see if it still is entangled..
Would the overall observable mass of the entangled particles increase with distance? What about in two different reference frames of time, like say a particle orbiting the earth entangled with a stationary one on its surface?
Your question doesn't have a simple answer, but if it did, it would involve signal-to-noise ratio within a given bandwidth. A radio receiver with a bandwidth in the audio range (~10 kHz) can amplify a signal by about ten trillion times its original power or a few million times its original voltage, before hitting the thermal noise floor of -174 dBm/Hz. These figures aren't exact (for one thing, they neglect the impedance change from a 50-ohm antenna input to an 8-ohm speaker) but the basic idea is correct: the noise floor at 25C in a 50-ohm system is -174 dBm/Hz + 10*log(bandwidth) dBm.
You can improve SNR by making your measurement near absolute zero, but you can't get rid of the noise entirely because some of it isn't strictly thermal in nature. Synchronous demodulation can let you recover information from below the noise floor, given a carrier of known phase. There are other tricks and hacks, but the bottom line is that you are still going to be at least ten or fifteen orders of magnitude away from being able to work with 37 significant figures in any real-world physical measurement. Integration times for such a measurement would have to approach heat-death-of-the-Universe durations.
Leon's getting larger.
Good thing there was a whole second half of the sentence addressing that...
Only one of the meter or the second can be independently uncertain.
Yes you're right I was thinking of mass (or force). In any case, the choice of which units to define and which to measure is arbitrary, so it makes sense to define the ones we have the least ability to measure.
Cesium has been pushed down to a relative uncertainty of 10^-14sec/sec
Which is a mind-blowing achievement, I think, but it's still a far cry from 10^-37.
However this only applies to direct measurement: A cesium clock's output frequency is stable enough that the GR-induced change in frequency due to raising it one meter higher, for example, is directly measurable because that change is larger than the random wander.
That's also amazing, and maybe there's a way to test this "entanglement makes particles heavier" idea, but we still aren't going to get measurements of anything down to 10^-37 that way. You mentioned "one meter higher", so that can't be better than our measurement of the meter (or second), right? I'm not a physicist. :)
Besides not seeing the trees and not the forest by ignoring the whole bit about the one part in 10^37 not being the likely target of measurement, the uncertainty principle as such doesn't apply to just a measurement of mass as momentum is not as simple as mass times velocity in quantum mechanics (or relativity either). Additionally, it would not apply to ensembled measurements, such as a large number of weak measurements on a repeatable experiment.
Turns out it makes no difference whatsoever what units you use. We don't have the ability to measure anything to 37 decimal places in any units. 7.4x10^79 atoms is two decimal places.
The photon has zero rest mass, yes.
E = mc**2 is a nice popularization; it's also wrong. It's actually E**2=(mc**2)**2 + (pc)**2, where p is the momentum. When momentum is zero, you can usually simplify this to E=mc**2, but a photon's existence is defined mostly by its momentum. Since m is zero for a photon, this means the energy of a photon is given by entirely by E=pc.
Hope this helps!
Radio receivers work through several mechanisms. First, you have an antenna that is only sensitive to a certain frequency range (but highly sensitive in that range). Then you have some kind of tunable resonant circuit that narrows down the range of frequencies even further, ideally to just the single frequency band you're looking for. When radio reception is good, the signal/noise ratio in that band is quite large, even if the signal is weak. That is, the radio signal is overwhelmingly the most powerful thing in that band, far more powerful than the noise in that band. So it's not really a measurement of '8 digits of accuracy'. It's more like 3 or 4 digits of accuracy.
A fool and his hard drive are soon parted.
No, at worst is these experiments to prove this cause the Earth to collapse to the size of a pea.
You're right it's even worse in qm. I am curious why you didn't mention that ?
The amount of change in mass you would be trying to detect is less than what the uncertainty principle allows for the creation of virtual particles over the length of time any reasonable experiment could run. Good luck with that.
Quantum entanglement IS the gravity we experience
"decimal places" should have been "significant digits".
Turns out the parent post was only accurate to within its first 44 characters.
If Pandora's box is destined to be opened, *I* want to be the one to open it.
Didn't RTFA, but still wondering: does this mean quantum encryption can be beaten by adding a "weight scale" to the transmission link?
If Pandora's box is destined to be opened, *I* want to be the one to open it.
I'm just really quantumly entangled.
Don't Panic.
If you read the pdf from arxiv you might learn that this is the work of a theoretician. He does the math. He doesn't attempt to measure anything.
I don't buy it.
It takes about 8 minutes for the gravity from the sun to reach the earth, but quantum phenomena would travel instantaneously.
Different things.
That's a little anecdotal, but all truth is on some level.