No evidence of time before Big Bang • Hacker News Board

Re: No evidence of time before Big Bang

#21

Post by rflrob » Mon, Dec 13, 2010, 4:13 AM UTC

itistoday wrote: post #11

The jury is still out. Gurzadyan dismisses the critical analyses as "absolutely trivial", arguing that there is bound to be agreement between the standard cosmological model and the WMAP data "at some confidence level" but that a different model, such as Penrose's, might fit the data "even better" " — a point he makes in a response to the three critical papers also posted on arXiv5. However, he is not prepared to sta…

From an Bayesian/Occam's Razor standpoint, Penrose's data could fit the data "even better", but as it's (arguably) a more complicated model, still have a lower posterior probability.

Would a universe with infinite time extent be easier to believe than one with a definite start point? I have enough trouble merely comprehending the possibilities, much less assigning prior probabilities to them.

Re: No evidence of time before Big Bang

#22

Post by absconditus » Mon, Dec 13, 2010, 4:24 AM UTC

danbmil99 wrote: post #20

Penrose would be a safer bet if he hadn't written "The Emperor's New Mind". Having completely flamed out on a subject I consider myself competent enough to judge him on, I'm much less willing to bet he's right in an area where I am less confident and knowledgeable.

I have never read "The Emperor's New Mind". What are its flaws?

Re: No evidence of time before Big Bang

#23

Post by hasenj » Mon, Dec 13, 2010, 4:26 AM UTC

iwwr wrote: post #6

jsmcgd wrote: post #5

Earlier quoted context omitted.

True, but if the first humans on Mars were to find the complete works of Shakespeare buried under the Martian soil, it probably wouldn't be prudent to dismiss it as a cosmological fluke.

True, but try sampling the CMB for long enough and you would find a few lines of Shakespeare in some encoding somewhere.

if you choose the encoding such that each letter in the alphabet encodes some Shakespearian paragraph, then you can find many lines of Shakespeare on this very discussion.

Re: No evidence of time before Big Bang

#24

Post by brc » Mon, Dec 13, 2010, 5:01 AM UTC

gasull wrote: post #16

Isn't time, somehow, a human abstraction? I mean, what really exists is movement. Earth spins over itself and we call it a day, Earth circles the Sun and we call it a year, a few quartz electronic pulses are called a second, etc. We use these events to measure time. Before Big Bang there was no movement, therefore, there was nothing to measure time with. If there's nothing to measure time with, there's no time.

True but if I travel away from a clock at light speed, time doesn't move anymore but I'm still moving.

Personally I like the idea that the big bang is a cyclical event - the universe expands until some point, then it collapses again. At some indeterminate point it expands again. Whether or not Earth gets recreated is for someone else to ponder.

Re: No evidence of time before Big Bang

#25

Post by jackfoxy » Mon, Dec 13, 2010, 5:21 AM UTC

absconditus wrote: post #22

danbmil99 wrote: post #20

Penrose would be a safer bet if he hadn't written "The Emperor's New Mind". Having completely flamed out on a subject I consider myself competent enough to judge him on, I'm much less willing to bet he's right in an area where I am less confident and knowledgeable.

I have never read "The Emperor's New Mind". What are its flaws?

It's been a while, but if I recall Penrose basically attacks the notion of "stong AI". Others, e.g. Scott Aaronson, have ripped his argument to shreds. But not to dismiss Penrose's argument too quickly, Aaronson did devote an entire university course to presenting the counter argument http://www.scottaaronson.com/democritus/. I think there is a case to be made against strong AI along the lines of "just because a posteriori you can model anything digitially does not make it so", but apparently Penrose failed. (And don't get me wrong, I'm not the guy to make the case either.)

Re: No evidence of time before Big Bang

#26

Post by nphase » Mon, Dec 13, 2010, 7:15 AM UTC

gasull wrote: post #16

Isn't time, somehow, a human abstraction? I mean, what really exists is movement. Earth spins over itself and we call it a day, Earth circles the Sun and we call it a year, a few quartz electronic pulses are called a second, etc. We use these events to measure time. Before Big Bang there was no movement, therefore, there was nothing to measure time with. If there's nothing to measure time with, there's no time.

Periodic movement is what we use to measure time, yes. But I can't imagine that time is simply a human abstraction. Just because there's nothing to measure time with doesn't mean time doesn't pass, right?

My brain doesn't like the idea of time in the context of relativity. Just because the relative (nominal?) measure of time changes as the forces of the universe may or may not cause it to doesn't mean the absolute (real?) period I wait for the train every day changes. Just because the clock stands still while you're moving away from it at light speed doesn't mean "time" hasn't been spent moving away from it.

(I use nominal and real because, oddly enough, economics is the closest thing I can relate this to.)

Re: No evidence of time before Big Bang

#27

Post by kingsidharth » Mon, Dec 13, 2010, 7:15 AM UTC

gasull wrote: post #16

Isn't time, somehow, a human abstraction? I mean, what really exists is movement. Earth spins over itself and we call it a day, Earth circles the Sun and we call it a year, a few quartz electronic pulses are called a second, etc. We use these events to measure time. Before Big Bang there was no movement, therefore, there was nothing to measure time with. If there's nothing to measure time with, there's no time.

I can't agree more. What I see time is as 'infinite now'. That's all that exist.

There is now, now now now now now & now...

We think it's tomorrow in Australia already but it's now. I can imagine that there was 'now' before Big Bang, since Big Bang happened in the now.

Re: No evidence of time before Big Bang

#28

Post by russellallen » Mon, Dec 13, 2010, 8:06 AM UTC

jackfoxy wrote: post #25

absconditus wrote: post #22

Earlier quoted context omitted.

I have never read "The Emperor's New Mind". What are its flaws?

It's been a while, but if I recall Penrose basically attacks the notion of "stong AI". Others, e.g. Scott Aaronson, have ripped his argument to shreds. But not to dismiss Penrose's argument too quickly, Aaronson did devote an entire university course to presenting the counter argument http://www.scottaaronson.com/democritus/ . I think there is a case to be made against strong AI along the lines of "just because a pos…

I'm always suspicious of phrases such as "ripped his arguments to shreds" especially in such a young and contested field as AI and doubly when dealing with the difficult issues of sentience and Strong AI...

I'm not accusing you of anything, but as a general comment, without necessarily supporting them, the response to his arguments on this issue often seem to involve overly emotive language.

Re: No evidence of time before Big Bang

#29

Post by fooandbarify » Mon, Dec 13, 2010, 8:06 AM UTC

gasull wrote: post #16

Isn't time, somehow, a human abstraction? I mean, what really exists is movement. Earth spins over itself and we call it a day, Earth circles the Sun and we call it a year, a few quartz electronic pulses are called a second, etc. We use these events to measure time. Before Big Bang there was no movement, therefore, there was nothing to measure time with. If there's nothing to measure time with, there's no time.

If a tree falls in the forest...

I love to see the connection between science and philosophy. I used to see philosophy as useless, and in modern practice it often seems that way, but I think it's fair to say that all science has philosophical roots - in this case, what is time?

Isn't time, somehow, a human abstraction?

What about space? Another dimensional abstraction? It becomes a semantic argument. A valuable one, but still - it is quite possible (probable?) that all human understanding is an abstraction of sorts. The fun part of engineering is learning to build stuff using the abstractions that we have experimented with enough for their behaviour to be predictable to some extent.

Re: No evidence of time before Big Bang

#30

Post by jey » Mon, Dec 13, 2010, 8:11 AM UTC

jackfoxy wrote: post #25

absconditus wrote: post #22

Earlier quoted context omitted.

I have never read "The Emperor's New Mind". What are its flaws?

It's been a while, but if I recall Penrose basically attacks the notion of "stong AI". Others, e.g. Scott Aaronson, have ripped his argument to shreds. But not to dismiss Penrose's argument too quickly, Aaronson did devote an entire university course to presenting the counter argument http://www.scottaaronson.com/democritus/ . I think there is a case to be made against strong AI along the lines of "just because a pos…

I don't think it's fair to say that Aaronson's course was devoted to debunking Penrose. It just happens that Penrose is very good at explaining these concepts, so his (wrong) book on consciousness (which contains a lot of physics) was used as the "textbook".