Max Tegmark - Are There Multiple Universes?

Multiple universes? The idea sounds astounding. Our universe is immense by itself. How could there be more than one? How can scientists come to believe in more than one universe? What’s more, multiple universes can be generated by radically different mechanisms. But what’s a ‘universe’ anyway? The whole vast ensemble of universes is now called a ‘multiverse’.





Max Tegmark is Professor of Physics at Massachusetts Institute of Technology. He holds a BS in Physics and a BA in Economics from the Royal Institute of Technology in Sweden. He also earned a MA and PhD in physics from University of California, Berkeley.


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[TerryBollinger]

4:58 Tegmark “... Heisenberg uncertainty ... says [the balanced pencil] will fall ... in all directions in a ... so-called quantum superposition ... that’s how easy it is to create ... quantum parallel worlds.” No. The _observed_ physics is that if you can shield the pencil from all scales of external linear momentum interactions, even ones as minute as one photon reflecting from the pencil, then — and _only_ then — you must switch to a quantum representation of the pencil’s angular state. That is an entirely different statement from saying all perfect symmetries “must” go quantum.

Even if you manage to keep a balanced pencil isolated from the rest of the universe, it’s the pencil’s _angle_ — its positional relation to the rest of the universe — that becomes an infinite superposition, not the pencil. Notably, an infinite superposition of angles has no additional energy cost, while an infinite superposition of _pencils_ has an infinite energy cost that would create a black hole. Since we seldom observe pencils turning into black holes, it’s a good bet that the superposition math stands for angles, not pencils.

Feynman’s lecture on electrons self-interfering as they pass through two slits provides a cautious and insightful analysis of such issues. In particular, he points out the curiously direct relationship between photon momentum wavelengths and the degree of localization of the electron near the slits.

That lecture is a beautifully specific and underappreciated example of how “wave collapse” is neither an all-or-nothing concept nor an experimentally inaccessible one. Feynman notes, for example, that the degree of “collapse” of a quantum wave never exceeds the minimum photon wavelength, which also gives the photon’s momentum. That kind of specificity sounds far more like a nonlinear and irreversible spacetime event than it does the formation of new, _unobservable_ universes.

The phrase “I believe” pops up a lot in this video. One can, of course, interpret equations derived from experiments any way one wishes. Still, Feynman’s deep respect for the experimental sources behind the equations seems like a good starting point for any interpretation.

[2022-12-19.02.32 EST Mon]


ADDENDUM: In my sarxiv dot org blog version of this comment, I added the following title and preamble:

*Infinite Universes Versus Losing a Puppy*

PREAMBLE: If you lose a puppy, the puppy doesn’t cease to exist, replicate infinitely, or care much that you lost it. You merely lack the information to find it and thus can make only broad remarks about the expanding circle of where the puppy may be. Physics has a more robust version in which recent information on the puppy’s location isn’t just hard to find but does not exist anywhere. We call that a quantum state. Once again, though, the puppy doesn’t care. It just wonders why everything got so very dark for a while.

[meesalikeu]

max is also a good listener — he answers the question and relates it to what is known or speculated. then adds his takes.

[nycgweed]

Just tell us how to control time and travel between our multi-verse and experience everything we can be

[mickeybrumfield]

It is incredible when the best theory we have leads to infinite universes and infinite parallel words, what a strange reality we find ourselves in.

[jamesruscheinski]

how might temperature / density fluctuations of cosmic microwave background (CMB) develop from single quantum energy fluctuation starting universe? could the fact that the temperature / density fluctuations of CMB are so near in value (one part in one hundred thousand?) indicate that the CMB developed from a single quantum energy fluctuation?

[jamesruscheinski]

if the cosmological constant expansion extends beyond 13.8 billion years from small hot dense state, then the cosmological constant expansion started before and outside or beyond small hot dense state? in which case a universe might not be demonstrable?

[jamesruscheinski]

can quantum fields develop from infinitesimal time beyond cosmological constant expansion of space?

[dry]

Latest War of the Worlds series mentions some of these concepts.

[User-kjxklyntrw]

The compressed universe condense into blackhole what happen with them, are they become parallel universe.

[NondescriptMammal]

I remember when the word "universe" meant everything in existence. By definition you could only have one universe. What does the word even mean any more in the context of "multiple universes"?

[jamesruscheinski]

how does inflation stretch out to small hot dense state that starts cosmological constant space?

[kricketflyd]

So if there are multiple univereses expanding infinitely then we are just somwhere along that growth and since the expansion is eternal then there must be an eternity of smaller construct in time? Where is it?

[anxious_robot]

I love Max because he has the imagination to "get it"...too many physicists get rigid thought. When you are the flee on the butt of a lion, and all you see is hair, you're going to have a hard time if you're stuck in rigid thought, so the guys like Tegmark and Maxwell who are childlike and have wonder and imagination are the key to figuring this out. Scientific method isn't going to work with the craziness that's going on here 'cause we can't see reality for what it is, so you might as well begin to use imagination and try to get off the lion's butt.

[SRAVALM]

4:22 "The most important thing to know in science is what we don't know"
And people never go looking for the answers which they already think they know.
The TRUTH, I've come to understand is not any answer, rather all seemingly answers in TRUTH is ONE.
What if, what is most important, is not the answers which we think we are seeking?
Samsara -- the wheel goes round, the wild goose chase. People foolishly think 'God' makes for more questions, which are unanswerable, but the fact is science, because it is endlessly revised and this is the nature of samsara, mutable and changeable, that one question leads to an answer only to lead to more questions. This would imply that seeking answers might not be the most important.

Metaphysics is #1 because it accords to psychology, physics(nature), theology and ontology, first Principles, Wisdom, arithmetic, math, geometry, cosmology, forms of epistemology. Although the focus is on first Principles, as if Philosophy, the focus is on the core.

[saulorocha]

“Whereof one cannot speak, thereof one must be silent.”

[User-kjxklyntrw]

Will we find older structure than big bang singularity out of our known universe

[jamesruscheinski]

effort to demonstrate a multiverse so as to evidence this universe is desirable, but looking for what is wanted might not lead to what is there and use up energy that can be better used in other ways?

[woodywu]

I love Closer To The Truth on YouTube. Many different theories and many great guests with much to ponder. People will agree or disagree with theories but still great to ask the questions 👍

[chugmania]

It's as if the universe picks the right scenario out of that multiple quantum probability state at each frame of time

[beowulf.reborn]

If inflation has a beginning, then can really be said that the entirety of Space, or the Multiverse, is at any one moment, truly infinite? Would it not be more correct to say that it is expanding, i.e. inflating, infinitely into the future?