Ed Witten on the Nature of Reality

Edward Witten: "I tend to assume that space-time and everything in it are in some sense emergent. By the way, you'll certainly find that that's what Wheeler expected in his essay. As you'll read, he thought the continuum was wrong in both physics and math. He did not think one's microscopic description of space-time should use a continuum of any kind - neither a continuum of space nor a continuum of time, nor even a continuum of real numbers. On the space and time, I'm sympathetic to that."

One of my comments in Quanta:

"Emergent space-time" is a category mistake. Specetime has already emerged - it is a deductive consequence of Einstein's constant-speed-of-light postulate:

"Special relativity is based on the observation that the speed of light is always the same, independently of who measures it, or how fast the source of the light is moving with respect to the observer. Einstein demonstrated that as an immediate consequence, space and time can no longer be independent, but should rather be considered a new joint entity called "spacetime."

Anything deduced from different premises would fall in a different category and would have nothing to do with Einstein's spacetime - combining the two concepts would be absurd. For instance, bringing granularity to spacetime is equivalent to painting spacetime in yellow. If the original concept of spacetime is unacceptable and should be replaced, then the underlying premise, Einstein's constant-speed-of-light postulate, is false and should be abandoned. The step is unavoidable if logic is obeyed.

Pentcho Valev

It is all a question of numbers after all...if a continuum is composed of 1e39 bits per angstrom, why is that different from a continuum?

Einstein's spacetime is a continuum approximation of a very large number of discrete quanta. So spacetime works very well and quantum works very well and all we need is a connection that also works very well...

The space-time continuum has issues. What is seen in a reference frame has to be a sensory product or product of a device, post receipt and processing of EM signals. Vision requires that causal order of EM signal receipt preceding product seen. The process from detection of signal to product generation gives a resolution to the product so that it is not a continuum. Whether because of the limited number of cells of the visual cortex or pixels display-able on a screen.

Quote: "I tend to assume that space-time and everything in it are in some sense emergent." Edward Witten. Yes, it has to be because Einstein was referring to what is seen. Being a physicist and not a biologist the process of seeing was not built into the work.

Nima Arkani-Hamed (06:09): "Almost all of us believe that space-time doesn't really exist, space-time is doomed and has to be replaced by some more primitive building blocks."

Any substitute for spacetime that emerges from "some more primitive building blocks", that is, is deduced from premises different from the principle of relativity and the constancy of the speed of light, has nothing to do with Einstein's spacetime. The two fall in different categories. The new "spacetime" could replace the old one, but then the rejection of Einstein's spacetime would entail that at least one of Einstein's 1905 postulates is false.

Marcelo Gleiser: "The challenge is to somehow bring the notion of granularity to spacetime, bring the discrete to the continuous. This is the problem that has baffled theoretical physicists for at least half a century."

This is insane. Spacetime is not an ab initio model that one can modify, e.g. by introducing granularity. It is a DEDUCTIVE CONSEQUENCE of Einstein's constant-speed-of-light postulate, and if the consequence is unacceptable, the postulate is false (logic forbids the combination "true postulate, unacceptable consequence"). In other words, you cannot "retire" Einstein's spacetime without declaring the postulate false:

What scientific idea is ready for retirement? Steve Giddings: "Spacetime. Physics has always been regarded as playing out on an underlying stage of space and time. Special relativity joined these into spacetime... [...] The apparent need to retire classical spacetime as a fundamental concept is profound..."

Pentcho Valev

All due respects for Ed Witten, but quantum communications are looking very realistic today. And it's the Chineese whom are taking the lead, at least publicly, with the first of a planned 20 satellites. It takes no great leap of understanding to recognize that an instantaneous correlation of paired events making communications undetectable in the first place, let alone decipherable, would render any adversary blind in any theatre of operations militarily. And of even greater import in terms of economic impact which historically drives nation states into armed conflict, establishment of a real time quantum com network would corner the global market in high volume - high frequency trading in financial markets. Recall how Galileo's improvement of the telescope (spy glass) made his laboratory, deductive scientific methodology financially possible by the immediate high demand of shipping interests for his product which enabled them to sight incoming vessels sooner than their competitors and marshall their agents to the dockside ahead of the competition.

Difficult as it may be for many to accept, an inherently rigid connectivity across a separation in space requires that spacetime must exist if there is any physical existence at all. And that the august Mr. Witten had it backwards. Energy is the stress (tensor) of the parallelized physical existence of space and time, and that stress energy follows a natural existential form in which the amount of such energy in concentrations must conserve space in a self-gravitational field of time where the coherence of simply connectivity of that energy is self limiting to a range of mass:energy unitary field percipitates in amalgamation globally - witnessed in the universal gravitation first approximately defined by our old and great, though rather odd, father of the modern world, Isaac Newton. It is in that conservation of space itself from which the behavior of energy across density variation that what we call a 'geometry' arises; the orthogonal relationship first identified by Mike Faraday co-existing with a spherical relationship where any equidistant point in a spherical boundary is simply connected at light velocity as physical inertia from a zero point center, which Einstein first identified ( you just can't define it mathematically as a co-existence of orthgonality and inter-spherical in Euclidean terms, hence General Relativity).

Like it or not, what is deducible from non-classified sources, the ChiCom are beating the western scientific consensus in quantum interpretation to the punch bowl. jrc

John,

Your comment about "making communications undetectable in the first place, let alone decipherable" is not quite correct. The communications are potentially both detectable and decipherable. But they are non-compromisable, since, for example, it is possible to determine that someone has attempted to intercept a distributed key. In effect, an adversary can jam the system by constantly attempting to intercept such a system. Thus, while one might know when the system is in a secure state, that state can be denied by a suitable denial-of-service attack. Denying an adversary their secure form of communications, in order to force them to use an insecure one, whenever it is essential for them to communicate, is a common strategy in communications warfare.

Rob McEachern

Thanks Robert,

You are quite correct. What the ChiCom (for the politically youthful; the 'Com" means 'communist' which today exists manifestly only by name not doctrine) do publicly acknowledge is that the most challenging problem has been in maintaining orbital critical LOS alignment. It is only in that trajectory that an intercept (quantum interference) can occur. Space based laser beam interruption might be worth looking at, though the incidence of disruption might be random at a level of the uncertainty principle. jrc

perhaps...

lambda/alpha | h/-8pi

As discreet sensors of some kind or another have to collect the em signals prior to their processing, discreetness is input to the production of seen space-time products. Even though some aggregation and averaging of the information generated from the signals occurs it isn't amalgamated into a fully continuous whole. The information is carried by discreet neurons or circuits. The information that ends up as the product is confined to the discreet components of the host surface.

Hello everyone,

Needed some help please with a question.

Suppose we have an equation f(t) which is a function showing the displacement of a particle at a different point in time.

[math]f(t)=x[1-exp[-(t/y)^z][/math]

How do I try to model this equation into a quantum oscillator, like Schrodinger?

Thanks!

Ajay Pokharel

Sorry for elementary question. Trying to understand quantum theory. Basic stuff. When detecting individual photons in double slit experiment, does each photon detected have the same intensity/energy or does intensity vary across interference pattern. Ie, is interference pattern caused by more and fewer photons or by photons with lower intensity? I assume all wavelengths are the same.

Same question when detecting interference pattern of electrons.

Realize this may be wrong place to ask this question. Proper link to do so would be appreciated. Thanks.

Ajay,

I was just looking in and gave your equation a quick eyeball. I see the general form and you might have something there, if you think of the particle 'skipping over the ocean like a stone'. Or at least one displacement to a different point in time. It would be the same thing as a particle shedding its relativistic mass more rapidly than it can shed its velocity, and the two continuous functions converging to a point of different time of the space. jrc