Physicists Debate Hawking’s Idea That the Universe Had No Beginning • Hacker News Board

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#81

Post by SomeOldThrow » Thu, Jun 06, 2019, 5:11 PM UTC

morsmodr wrote: post #37

quotemstr wrote: post #16

Earlier quoted context omitted.

Causality without time makes no sense. Even if you don't have a ticking clock, you can define "time" with a counter and a Lamport clock. Any time you have state, you have time. A timeless universe is hard to grasp.

Time is another dimension that we 'perceive'. Hence for our frame of reference, which is bound by time, asking what is outside this frame of reference makes no sense. But frames of references are relative and meant to be broken. Similarly it is hard to imagine any object that can be purely 2D in nature, because we are biased to perceive the world in 3D. So we think that every object has to be 3D, even the smallest or…

> The point I am trying to make is that time is just our perception.

So is causality—I'm not really sure what your point is.

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#82

Post by Balgair » Thu, Jun 06, 2019, 5:13 PM UTC

irrational wrote: post #62

Balgair wrote: post #54

Earlier quoted context omitted.

Wikipedia's 'Timeline of the Far Future' is a great article on the posibilities of our universe's fate [0]. Of note are the entries near the end of the list. Year 10^(10^(50)) : Estimated time for a Boltzmann brain to appear in the vacuum via a spontaneous entropy decrease [1] Year 10^(10^(120)) : High estimate for the time for the universe to reach its final energy state, even in the presence of a false vacuum. Year…

This kind of discussion always reminds me of the Asimov story "The Last Question" https://www.multivax.com/last_question.html

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#83

Post by sarego » Thu, Jun 06, 2019, 5:16 PM UTC

jvagner wrote: post #30

her_tummy_hurts wrote: post #28

I don’t thunk my brain could handle no beginning

With all respect, I think we generally live in a human society that has been built around that very constraint.

Curious to know why that is. Would you mind expanding?

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#84

Post by martincmartin » Thu, Jun 06, 2019, 5:21 PM UTC

djsumdog wrote: post #10

This seems different than the concept of infinite time, where prior to the big band there was something the collapsed into a ball of energy and maybe someday our universe will collapse back again (which has lost merit since we've seen matter in the universe isn't slowing down in spreading apart, but accelerating .. meaning in a few trillion years, atoms may be so far apart that light can't reach anything .. the event…

there is an assumption the shuttlecock is the Universe and there is nothing outside to observe the object.

It's not an assumption, it's explicitly part of the model.

Same with "What's south of the south pole." It ignores the stars and galaxies past Earth itself.

If I say "the latex in this balloon is like the surface of the earth," I'm not so much ignoring the stars & galaxies, they're just not part of the analogy.

Is your point that, for an object to be curved, there must be something for it to curve into? For example, in order for a 2D surface (like the latex in the balloon) to be curved, it necessarily must be in a 3D (or higher) space?

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#85

Post by psalminen » Thu, Jun 06, 2019, 5:22 PM UTC

irrational wrote: post #62

Balgair wrote: post #54

Earlier quoted context omitted.

Wikipedia's 'Timeline of the Far Future' is a great article on the posibilities of our universe's fate [0]. Of note are the entries near the end of the list. Year 10^(10^(50)) : Estimated time for a Boltzmann brain to appear in the vacuum via a spontaneous entropy decrease [1] Year 10^(10^(120)) : High estimate for the time for the universe to reach its final energy state, even in the presence of a false vacuum. Year…

This kind of discussion always reminds me of the Asimov story "The Last Question" https://www.multivax.com/last_question.html

Thanks. This was an amazing read.

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#86

Post by jdironman » Thu, Jun 06, 2019, 5:22 PM UTC

irrational wrote: post #62

Balgair wrote: post #54

Earlier quoted context omitted.

Wikipedia's 'Timeline of the Far Future' is a great article on the posibilities of our universe's fate [0]. Of note are the entries near the end of the list. Year 10^(10^(50)) : Estimated time for a Boltzmann brain to appear in the vacuum via a spontaneous entropy decrease [1] Year 10^(10^(120)) : High estimate for the time for the universe to reach its final energy state, even in the presence of a false vacuum. Year…

This kind of discussion always reminds me of the Asimov story "The Last Question" https://www.multivax.com/last_question.html

That was a great read. Asimov was always so far ahead of his time.

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#87

Post by brink » Thu, Jun 06, 2019, 5:23 PM UTC

sonnyblarney wrote: post #59

EdwardDiego wrote: post #53

Am I wrong, or are they arguing on matters of belief rather than evidence?

The word is 'speculation' not 'belief' that that's pretty much what all science is. The evidence usually comes later.

Yeah, but this seems trying to avoid the possibility of the universe having a beginning simply because it's unsettling; taking the less likely thought path because it conflicts with beliefs.

I'm not saying that's what it is, that's just what it seems like what's happening here to me.

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#88

Post by Balgair » Thu, Jun 06, 2019, 5:25 PM UTC

SketchySeaBeast wrote: post #70

deepsun wrote: post #51

Earlier quoted context omitted.

> what, if anything, is outside the observable universe The answer is similar to the time. Remember, in cosmology there's no really separate space and time, there's only space-time. So when you're looking at the edge of the observable universe, you really looking back in time. So the answer to the question "what is outside" is the same as "what was before". Or, in simpler words, the question is meaningless, as there'…

If you are restricted to the typical 3 dimensions of movement (and 1 through which we are non-optionally traveling) - you should either get to a physical boundary, or you end up in a loop, right? I mean, you won't travel so far you end up in Tuesday.

Sorta.

We are in this thing called space-time.

It came out of the Big Bang (we think).

There is a finite amount of it (about 45 GLY in radius, maybe).

You can only ever see about 14GLY of it due to some speed limits.

You can't get to an edge or boundary of space-time because it's not 3-D, it's curved in this really weird way.

There are a lot of holes in space-time that we're still thinking a lot about.

For some reason, the space-time is getting bigger and bigger, we think this is related to all that stuff in space-time, but we're really not sure.

Most of the stuff in it is not the same stuff as you are made of; most of the stuff seems to fall up, while the stuff you're made of falls down.

There is a lot more stuff that falls down than just the stuff you are made of.

There is a still a lot of things to learn about all of this, we're not really all that close to understanding it.

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#89

Post by jdironman » Thu, Jun 06, 2019, 5:26 PM UTC

sarego wrote: post #83

jvagner wrote: post #30

Earlier quoted context omitted.

With all respect, I think we generally live in a human society that has been built around that very constraint.

Curious to know why that is. Would you mind expanding?

Because if we have not beginning, we have no purpose. If we have no purpose, this is all really for nothing. I am not arguing whether it is or not, or whether there is a beginning, but lets look at it this way... You woke up this morning, that was the beginning of this day at night you will rest. Now, lets say there is no memory or record of 'waking up' beginning, we therefor cannot anticipate an end and everything we do now may feel for some less meaningful. I don't really know. I am just expressing my under-educated overthinking take on it.

Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning

#90

Post by MisterOctober » Thu, Jun 06, 2019, 5:27 PM UTC

gavanwoolery wrote: post #48

I have very little knowledge of astrophysics, but I thought it would be an interesting idea if the universe constantly recycled itself. That is, every so often it collapsed in on itself and produced another big bang. Theoretically some parts of the universe would have already achieved escape velocity, but the rest of it is gradually gravitating towards some center of mass. Is such a thing even feasible?

Lee Smolin makes an intriguing suggestion with regard to how the universe reproduces in his book "The Life of the Cosmos" -- I can't say I was persuaded, but I think it's worth reading