Thursday, December 1, 2022

Entanglement Discovered in a Quantum Computer

Lenny Susskind and others have been saying that wormholes and entanglement are the same thing.


Almost a century ago, Albert Einstein realized that the equations of general relativity could produce wormholes. But it would take a number of theoretical leaps and a “crazy” team of experimentalists to build one on Google's quantum computer. Read the full article at Quanta Magazine:
The idea seems to be that if entanglement and wormholes are the same thing, and quantum computers use entanglement to do super-Turing computations, then there should be some wormholes hiding inside a quantum computer. Seems like a joke to me, but I did not read the details.

See Peter Woit for details. At least one physicist calls it a publicity stunt. The quantum computer researchers have burned a lot of money, and need something to show for it.

Update: A comment:

Even if the headline isn’t strictly accurate (a topic for another time, although I think you’re splitting hairs here), what’s the harm? It’s a cool-sounding result which gets people interested in theoretical physics, science more generally. As long as science journalists are driving interest and engagement, I think they’re doing a good job. If you want to discuss bad science journalism, surely a better use of your time would be all the anti-science fake news coming from the populist right in the U.S.
I suspect that this view is common. Over-hyped phony stories generate interest and funding. If you want to be a good Leftist, you should not call out Leftist lies. Instead you should devote that energy to attacking right-wingers!

Update: Scott Aaronson admits that the wormhole story is a big hoax, promoted by physicists who should know better. He also discusses a new paper saying that quantum supremacy is impossible. He says it is no surprise to experts in the field who have known since 2016 that scaling up quantum computers will not work. He is still a believer:

So, though it’s been under sustained attack from multiple directions these past few years, I’d say that the flag of quantum supremacy yet waves. The Extended Church-Turing Thesis is still on thin ice.
That is, he says that he has not been proved wrong yet. Okay, but he hasn't been proved right either.


  1. Would it be possible for experimentalists to create an *acoustic* analogue to the worm-hole? Would it be cheaper? If they succeed in doing that, would it also get called just a worm-hole? i.e., without adding the qualifiers like ``acoustic'' and ``analogue''?


  2. Mass can not be assigned to a point (something with no physical extension) unless you are just screwing around with numbers like Hilbert did in a given space time that is eternal and contains only one mass (slight difference from anything that actually exists in our universe no?). Without the singularity with mass assigned to it, you don't get the ridiculous 'infinite density' bullshit mcguffen required for an entirely mathematical black hole.

    Points as physical objects that can carry mass, and infinite densities of anything (key bullshit word here is 'infinite') both need to be ejected from physics and science. They are both entirely non-physical, are entirely unmeasurable, and have no relation to observed reality. Badly assigned math is not science.

    Without the bullshit points (singularities) with mass assigned producing the bullshit infinite densities (which don't exist and can't be measured regardless)... the bullshit wormholes go poof in a (you guessed it) puff of even more delightfully odiferous bovine excrement. Funny how that works isn't it?

    1. You are correct in that a point-mass (and hence infinite density) is an abstraction from reality; it's not physically real.

      However, note that even in maths (let alone in physical theories), a point of singularity is *excluded* from analysis. Such an exclusion is a theorist's way of admitting that the way his theory has been abstracted from reality, some undesirable consequences have also come in, and they are such that the theory itself cannot be regarded to even apply at (or even encompass in itself) a point of a singularity. (A theory can have many points of singularities.)

      What is necessary for a region of space-time to function as a blackhole is not the singularity, but the behaviour in space-time *around* it.

      Mathematicians will simply stick to saying that point(s) of singularity is (are) excluded from analysis. Physicists too would toe the same line.

      If you ask me, I would say (after studies of comparatively simpler theories that still involve singularities) that one should expect that the actual physical behaviour would increasingly depart from the theory as the point of singularity is approached. In short, the theory is wrong not just at the point of singularity but everywhere! It's just that the *degree* of the wrongness decreases as you go away from a singularity, and so, in regions enough away, it can still give accurate enough results.

      All singular theories from physics and engineering have this common character: (a) Either the phenomenology or principles which can provide a better (non-singular) theory/model are not known, or,(b) even if they are known, the description would become too complex, and so, in practice, simplifying assumptions are introduced --- knowingly.

      For an example of (b): A molecular dynamics (MD) model for finding stresses around a micro-crack doesn't have the crack-tip singularity. But using it would require hours of supercomputer time (and many man-years of writing the software). In contrast, a continuum mechanics model does have singularity, but calculation of stresses using it is a routine problem even on unit tests (i.e., not even the end-sems); it requires only a calculator. And, the relevant results are equally accurate (if not better, because no homogenization of results is necessary).

      As an example of (a): In astrophysics, singularities are unavoidable because enough of additional phenomenlogy is not known. In short, people should treat the theory as just a model, not a fully accurate physical description.

      Yes, a theory having singularity is an *approximate* theory. But admitting so goes against the mathematician's grain. (Ditto, for the theoretical physicist.) ... You know how they talk and react. ... A mathematician (or theoretical physicist) would simply mumble, once again, that his analysis *clearly* says, that the point has been *exactly* excluded, and also, *clearly*, *all* the rest of his analysis is *exact* too. ... In short, the mathematician (and the theoretical physicist) has a knack of missing the point [pun intended].


    2. Ajit,
      There is no model of space time that can actually show two masses interacting in any way without hand waving since time is already compressed into the curved geometry, there is no movement possible, the model is utterly static...and gravity is all about describing movement. Case in point, describe an impulse to motion, like a space craft firing its rockets and accelerating in a given space time, I dare you.

      In any case, Einstein was merely being coy in avoiding the embarrassing problem of explaining how gravity exerts an influence at a distance without a mechanism other than 'because static curved geometry', even Newton was at least honest enough to say he simply didn't know how gravity worked, he could only model the effects of what it did.

      Unless you have discovered a mathematically legitimate way to insert additional masses into highly non-linear pseudo-riemannian bullshit equations, you can't stack up masses in a given space time. This isn't a minor esoteric theory problem that just needs a little nudge, this is outright failure of a theory to even describe a two body gravitational interaction.