The Nature of the Universe, Time Travel and More...
- Thread starter Will The Serious
- Start date
Cantor was another one who struggled with the frustrations of circular reasoning. Depression and paranoia plagued Kurt Gödel as well.
-Will
It would certainly be probabilistic if time travel were actually possible. Humpty Dumpy reassembled, all the king's horses and all the king's men riding back to the castle all over again.
-Will
There is a consensus that the second law of thermodynamics is probabilistic.
The 2nd Law of Thermodynamics -- A Probabilistic Law - Nexus Wiki
www.compadre.org
Indeed they did.
Do you think the universe has a shape with a fixed border?
Same for our galaxy do you think we have a border or we could exit our galaxy into the space between galaxies?
Same for our galaxy do you think we have a border or we could exit our galaxy into the space between galaxies?
Shape of the universe - Wikipedia
Personally, I don't see enough evidence and the answer might remain unknowable indefinitely, given that we cannot obtain information beyond the cosmological horizon. My suspicion is that it's finite without boundary, but with a larger volume than what we can observe within the cosmological horizon.
The external galactic barrier exists only in the fictional TOS galaxy as far as we are aware, but there might exist a barrier to cosmic rays near the centre of the Milky Way.
A GeV-TeV particle component and the barrier of cosmic-ray sea in the Central Molecular Zone - Nature Communications
Galactic center is one of the most important cosmic-ray sources. Here, the authors show GeV-TeV cosmic ray density in the central molecular zone is lower than the cosmic ray sea component, suggesting presence of high energy particle accelerator at the galactic center and existence of barrier.
www.nature.com
In this case, I speculate that an enhanced magnetic field - possibly embedded in an expanding plasma - might do the trick. This would be similar to the exclusion of lower energy cosmic rays from the inner solar system by the heliospheric magnetic field carried out from the Sun by the solar wind. The kinetic energy of incoming cosmic rays is lowered as they encounter the outflowing solar wind with its embedded magnetic inhomogeneities and those with lower energy are more actively convected outward. Some still reach the Earth but their intensity is lower than outside the heliosphere. The appropriate equation is Eugene Parker’s transport equation. An alternative approach is to model the paths of individual cosmic rays and aggregate these using Monte Carlo analysis.
Fractional Parker equation for the transport of cosmic rays: steady-state solutions | Astronomy & Astrophysics (A&A)
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
www.aanda.org
However, galaxies do not have well-defined borders, edges or rims. Stars are sometimes ejected from them permanently and galaxies collide - as Andromeda and the Milky Way might do in about four billion years time.
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I would suppose part of the answer to size and shape of the Universe is definition. If there is an edge to the Universe it must be defined in such a way as to not include the absolute "nothing" beyond whatever edge makes the universe deffinibly separate from that "nothing". Or perhaps, beyond the edge of the Universe is a solid "One Thing" so complete and uniform as to be absolute in impenetrability. It would be so solid as to have no matrix of material, no flexibility, no between particles. To strike its boundary would have instantaneous results everywhere all at once outside our Universe. That is, if the absolute massiveness of the "Not Universe" allowed for anything to affect it.
-Will
-Will
I think that it's a bubble that is constantly growing with no visible end in sight.
Another vote for a bubble
Doesn't that open the question to, what is the bubble in? And, why isn't what the bubble is in part of the Universe?
-Will
-Will
Sounds like the concept of eternal inflation, wherein the so-called Big Bang is just an infinitesimal speck. That part of the actual universe which has not yet inflated might well be infinite. The cosmological horizon due the finite speed of light, being much less than the inflation speed, potentially hides the vastness of the whole thing as well as rendering our speculation as metaphysics.
I agree with the Lower Decks interpretation of Universes.
Our Universe is one bubble, in a larger infinite Multi-verse Bubble Bath full of various sized bubbles.
Everything is part of a larger Universe/Reality.
But there are ways to cross in between Universes/Realities.
Yes! And granted that no single part of space can expand faster than the speed of light since "C" is the known Speed Limit, most parts of empty space grow on it's own, eventually the sum of all the parts of space expanding will have a combined expansion rate faster than the speed of light when viewed from a larger scale / perspective.
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If inflation theory is correct, the speed of expansion outside our bubble is far higher. It's always seemed somewhat contrived to me and although it explains the observations, it doesn't appear to be falsifiable. However, the inflaton field gets rid of worrying about what happens outside. The late Sir Fred Hoyle would have approved of the infinite and eternal nature of it all. Just the one Big Bang - as he termed it - was too encouraging of creationism for him as an atheist.
So, it is a matter of definition. If the term 'universe' doesn't mean everything, we tack a modifier to it and say, "multiverse". Does that mean Everything? What shape would that be? Where are its limits. This is a "turtles all the way down" scenario. Infinity plus one...
It also shows a little arrogance for the human-centric perspective. If it is beyond what we can see, it is outside the Universe and must mean another universe.
So true. Another appealing argument for agnosticism.
-Will
I had the argument about whether universe should encompass multiverse fifty years ago at school. I'm not going to revisit it.
Basically this.
What was your conclusion at the end of the argument?
It wasn't resolved because the other guy was a wannabe philosopher who liked arguing just for the sake of it, but my view was that the universe is everything that we can observe and the multiverse is the universe plus everything else that we can't observe. If you can neither interact with it nor observe it, it's metaphysics in any case. One might ascribe certain phenomena to parallel universes, but it's not falsifiable as far as I'm aware.
Sabine thinks the Alena tensor proposal is nonsense:
After watching her analysis, I agree, although I won't be resorting to arson.
The idea of hidden dimensions and parallel universes are, even if put into an academic paper, untestable and most of the attempts to try and probe them (e.g. proton collisions at the LHC going on the idea of compact higher dimensions making miniature black holes possible) have failed.
A lot of modern high-energy theoretical physics that's not lattice QCD might as well be theology.
Indeed, it seems to be the modern equivalent of discussing how many angels can dance on the head of a pin.
