Whenever I see an image like the one in the article of a cone showing the start of the universe it reminds me of something being shot. Or an object with great velocity striking a stationary object. One end is the point of impact and the cone is the debris spraying outward.
Physicists Debate Hawking’s Idea That the Universe Had No Beginning
141–150 of 299 posts
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#142Say we could break any physical rules of our current universe, is there a good theory that would explain how something might have been created out of nothing? i.e. imagine for a second that we're in a simulation and that the current laws of physic are just arbitrary created by a "host". This "host" could have very different physical laws. Could we think of any theory that would explain the creation of something out o…
You might be interested in Our Mathematical Universe by Max Tegmark. He tries to argue that, fundamentally, the universe is "just math." In other words (glossing over enormous complexity here) if the basic axioms of math are true, the universe must exist. I have to admit I didn't fully buy the line of reasoning. But it's very interesting.
> if the basic axioms of math are true
Isn't the problem that you can't prove axioms. We intuitively "know" them to be true but without proof.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#143> Just as a shuttlecock has a diameter of zero at its bottom most point
As a lay person this - right from the starting block - is what messes me up. I.e. something that exists cannot logically have a zero diameter part. Anything zero does not exist.
Most related theories have similar kinds of initial premise that you must just accept.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#144Pure nothingness has no potential for creation. The laws of physics don't invent themselves, so it would seem that true "nothing" never existed. I'm not talking about the quantum soup of the vacuum of space, because that is something. If we take Hawking's idea that the universe smoothed out to a zero point where there was no time and nothing else, how does that point because laws of physics, gravity, etc? What proper…
There was no "before" as time itself was created with the universe.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#145> Just as a shuttlecock has a diameter of zero at its bottom most point As a lay person this - right from the starting block - is what messes me up. I.e. something that exists cannot logically have a zero diameter part. Anything zero does not exist. Most related theories have similar kinds of initial premise that you must just accept.
> something that exists cannot logically have a zero diameter part
Do elementary particles exist?
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#146Earlier quoted context omitted.
Boltzmann brains may not occur after all [0], which is reassuring [2]. See De Sitter Space Without Dynamical Quantum Fluctuations [1]. [0] http://www.preposterousuniverse.com/blog/2014/05/05/squelchi... [1] https://arxiv.org/abs/1405.0298 [2] https://arxiv.org/abs/1702.00850
Oh man, all that is decidely out of my realm of expertise. Is there a TL;DR on why BBs are not possible?
Essentially in that paper Carroll argues that the dilution away of the matter means that incoming radiation at a point p in the far future when there are billlllions of light-years of empty space around p is so redshifted that it makes no difference to the massive particle at p, even if by random chance a whole mess of incoming radiation arrives all at once.
The counter-concern is that in a truly infinite universe, enough ultra-infrared energy arrives at p that (with more realistic matter) pair-production occurs in such a way that bound states (nuclei, atoms, molecules, brains-with-memories) start forming.
Infinity is hard to cope with, and Carroll likes playing with those.
Boltzmann Brains are infinitesimally unlikely in the really foreseeable future of our universe, but if we jump from foreseeable (say, trillions of years) to infinite, all sorts of weird stuff can happen. Including your brain in a jar, convinced that it is not in a jar but living (after being conventionally born) in a universe full of other humans and cats and stars and galaxies.
What annoys Carroll is that small fluctuations are much more probable than large fluctuations, and a brain-in-a-jar-with-false-memories requires a much much much much (insert several more "much" here) much smaller fluctuation than a real universe with a hot big bang and structure formation and evolution of primates who walk around staring at smartphones.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#147Pure nothingness has no potential for creation. The laws of physics don't invent themselves, so it would seem that true "nothing" never existed. I'm not talking about the quantum soup of the vacuum of space, because that is something. If we take Hawking's idea that the universe smoothed out to a zero point where there was no time and nothing else, how does that point because laws of physics, gravity, etc? What proper…
There was no "before" as time itself was created with the universe.
How was time created, time means changing state, without time there is no change. So in order for a change to happen in the existence of time you'd need a further time dimension; then you're just shifting the problem up the stack.
Creation of time requires a meta-universe of some sort. Though perhaps there's some other way to conceive time not existing further back than a given point that works around creation being something that's done within a temporal dimension.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#148Earlier quoted context omitted.
It's nonsensical to wonder what happened in our universe before it existed, but if our universe has an external superuniverse, it's not illogical to wonder what happened there that caused our universe to exist.
> if our universe has an external superuniverse This is also meaningless, scientifically: there is nothing you can measure which is outside the universe. Things like a holographic universe are inherently untestable. I hope we continue looking for testable things, but this speculative path rapidly leads away from science and physics and into "linguistic tricks to confuse humans". It's not even philosophy at that point…
There are still ways we can reason about it. If we come up with a model of a super-universe and then find that model says that universes like ours are more likely to exist, then it can be evidence for the super-universe. We could possibly use the model of the super-universe to make predictions about our own universe.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#149Cosmology is deeply disturbing if you think about it too long. Why should the universe exist? What is a causeless cause? How can something come from nothing? Regardless of the precise mechanisms involved, at some scale, some kind of steady-state cyclic model seems unavoidable --- the whole idea of existence not existing is bizarre and puzzling. The only way out of the causeless effect problem is to nop out of the eff…
That's only disturbing if you believe everything is simple enough that humans could comprehend it straight away. If you accept that some stuff is beyond our understanding, and will be for quite a while yet, everything is much less bothersome. Accept that you are fallible and the universe is fine. I'm not saying this is easy though.
There's good reason to believe that humans can understand everything that exists: we're Turning complete, and mathematics admits no higher category of functions than those that a Turing machine can compute. We may not be able to physically compute every function, but we can devise a plan for computing any function, and isn't that tantamount to being able to understand anything in principle?
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#150Pure nothingness has no potential for creation. The laws of physics don't invent themselves, so it would seem that true "nothing" never existed. I'm not talking about the quantum soup of the vacuum of space, because that is something. If we take Hawking's idea that the universe smoothed out to a zero point where there was no time and nothing else, how does that point because laws of physics, gravity, etc? What proper…
The problem in your argument is the word 'become'. To 'become', something has to not be so and then later be so- with 'later' implying time on both sides. Hawking's argument is that there is no time on the other side.
My interpretation is that the energy of the universe exists in time and space, evolving across the dimension of time. But it has an edge called 'the beginning'. That's the shape of the beast- a defined edge that we cannot reason outside of.
Edit: At least, I presume your 'because' was meant to be 'become'.