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John C. Mather: “There is no first moment of time” (2017)

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Re: John C. Mather: “There is no first moment of time” (2017)

#71

Post by idealmedtech »

kadoban wrote: post #54
idealmedtech wrote: post #39

Earlier quoted context omitted.

There's whole _fields_ of inquiry that either take or leave the axiom of choice; so yes, absolutely.

Is that the kind of statement Godel was talking about? Seems to me to be somehow different. It's not really true or false, it's an arbitrary choice, so it's just something you either decide is part of your system or not, not a true statement that's unprovable. Maybe I'm missing something?

Axiom of choice isn't really relevant to Godel's work, except for the fact that it's part of axiomatic systems. But in response to your comment, I was pointing out that there's lots of interesting math that comes from the results of his work; namely under different axiomatic systems you can find different and interesting results.

Re: John C. Mather: “There is no first moment of time” (2017)

#72

Post by mistermann »

anonymousiam wrote: post #44
mistermann wrote: post #38

Earlier quoted context omitted.

> It's not valid to extrapolate backward to a time before our universe existed. And yet, you've managed to do just that! > This is a concept that I've tried to explain to others for years, but it's difficult for most people to grasp. Not surprising since not all people experience the same reality.

"And yet, you've managed to do just that!" How?

"Before the existence of our universe, there was no time."

It seems almost impossible to avoid this sort of thing (~omniscience), at least when discussing certain topics, but it can be a lot of fun to try. Noticing it in others when reading comments is much easier, and a good form of practice.

Re: John C. Mather: “There is no first moment of time” (2017)

#73

Post by sounds »

aasasd wrote: post #66
sounds wrote: post #59

Earlier quoted context omitted.

I'm going to skip the more philosophical part of your question. Or in other words, if you're asking, "is there any observable evidence of something outside the observable universe?" My answer is: no comment at this time. If you're asking, "what did John C. Mather mean in talking about the edge of the universe?" I'm not John C. Mather, but here's my guess -- The curvature of the universe [1] has been computed from dis…

Thanks! > no matter how far in the future you plant an observer, the speed of light is not fast enough for them to observe the entire observable universe I'm guessing it's just ‘universe’ here, instead of ‘observable universe’—since afaiu the definition is that light inside the observable universe is able to reach us? So, if I understand the whole comment right, a curved universe is guaranteed to have an edge, but wi…

> if I understand the whole comment right, a curved universe is guaranteed to have an edge, but with a non-curved one it's a toss-up because no one knows what it would look like.

A curved universe doesn't "have an edge," I'm referring to Euclidean and non-Euclidean geometry [1]. As in, if the curvature is truly and perfectly zero, then the space-time we live in goes on forever. If it has even the tiniest curvature, then it curves back onto itself and is non-Euclidean.

If it is truly and perfectly zero, then all I'm trying to say is that it goes on forever like an "ideal" 2D plane or 3D space.

[1] https://en.wikipedia.org/wiki/Plane_(geometry)

Re: John C. Mather: “There is no first moment of time” (2017)

#74

Post by sounds »

aasasd wrote: post #66
sounds wrote: post #59

Earlier quoted context omitted.

I'm going to skip the more philosophical part of your question. Or in other words, if you're asking, "is there any observable evidence of something outside the observable universe?" My answer is: no comment at this time. If you're asking, "what did John C. Mather mean in talking about the edge of the universe?" I'm not John C. Mather, but here's my guess -- The curvature of the universe [1] has been computed from dis…

Thanks! > no matter how far in the future you plant an observer, the speed of light is not fast enough for them to observe the entire observable universe I'm guessing it's just ‘universe’ here, instead of ‘observable universe’—since afaiu the definition is that light inside the observable universe is able to reach us? So, if I understand the whole comment right, a curved universe is guaranteed to have an edge, but wi…

> Does the author essentially mean that the smaller universe still had only a part of it observable?

No, I think John C. Mather there is focused wholly on the concept of infinity. So even if the whole observable universe (30 billion light-years across) got squished to the size of a golf ball, the whole universe (infinity light-years across) would still be infinite, because multiplying infinity by some small constant still equals infinity.

Re: John C. Mather: “There is no first moment of time” (2017)

#75

Post by TedDoesntTalk »

russellbeattie wrote: post #67
TedDoesntTalk wrote: post #51

Earlier quoted context omitted.

> So really, time started when reality started wobbling “It’s all wiggles” —- Alan Watts

I never heard of him before! He was definitely into wiggles. And psychedelics apparently. > "But the real world is wiggly, wiggly, wiggly. Now when you have a wiggly system like a cloud, how much wiggle is a wiggle? Well, you have to draw the line somewhere. And so people come to sorts of agreements about, uh, how much of a wiggle is a wiggle; that is to say a thing. One wiggle, you can always reduce any one wiggle i…

Many of his lectures are on YouTube (audio only). I hope you enjoy him. He’s a great entertainer/speaker.

Re: John C. Mather: “There is no first moment of time” (2017)

#76

Post by aasasd »

sounds wrote: post #73
aasasd wrote: post #66

Earlier quoted context omitted.

Thanks! > no matter how far in the future you plant an observer, the speed of light is not fast enough for them to observe the entire observable universe I'm guessing it's just ‘universe’ here, instead of ‘observable universe’—since afaiu the definition is that light inside the observable universe is able to reach us? So, if I understand the whole comment right, a curved universe is guaranteed to have an edge, but wi…

> if I understand the whole comment right, a curved universe is guaranteed to have an edge, but with a non-curved one it's a toss-up because no one knows what it would look like. A curved universe doesn't "have an edge," I'm referring to Euclidean and non-Euclidean geometry [1]. As in, if the curvature is truly and perfectly zero, then the space-time we live in goes on forever. If it has even the tiniest curvature, t…

> A curved universe doesn't "have an edge"

Ah, indeed, quite a brain fart moment from me there, since you explained the structure right in the previous comment. Pondering cosmology while sleep-deprived is suboptimal, I guess.

Though now I'm curious about this:

> If it has even the tiniest curvature, then it curves back onto itself and is non-Euclidean

Would it be possible in theory that the three dimensions are curved like a helix—so they have constant curvature but don't intersect themselves? This way the universe would still stretch infinitely in most directions, but would be non-Euclidean, and you'd need to know where the ‘axis’ is to be able to see in a direction that shortcuts to another one.

Re: John C. Mather: “There is no first moment of time” (2017)

#77

Post by wruza »

blooalien wrote: post #69

"If a tree falls in a forest and no one is around to hear it, does it make a sound?" https://en.wikipedia.org/wiki/If_a_tree_falls_in_a_forest This feels kinda like that… Certainly "time" passes, but if nobody is measuring it (or even conceiving of it as "a thing") at what point is it relevant in any way?

Certainly

I certainly have vague ideas about how it works, but it feels like some physicists feel that time is emergent too. Even if not true, consider this thesis: There is no time at all, not before BB, not after. We only “see” our time because it is a consequence of non-euclidity of what we call spacetime, which is otherwise a timeless structure in which one could recognize “entropy” vectors. Then our emergent time could not exist before BB. And when you apply “exist” or any other temporal tense to that structure as a whole, it’s just a semantic error.

Re: John C. Mather: “There is no first moment of time” (2017)

#78

Post by wruza »

TedDoesntTalk wrote: post #55
xwdv wrote: post #20

Not only might there not be a first moment, there might be no time at all. Every possible instant of time could be randomly distributed with some very small but not infinitely small probability of occurring. On an infinite timeline, everything should occur, forever. When a moment occurs, a structure of your brain exists coded with memories of past events that feel real but never happened. Since each moment is pure an…

> you do not perceive the trillions of years that could pass in between two moments occurring, nor do you have any way to realize you are perceiving moments out of order or that other possibilities of realities exist This is intriguing. But how does cause and effect work? If there is no “external state”, say I burn my hand by spilling hot coffee on it. There’s a burn in my skin. Trillions of years pass and I experien…

There is no cause and no effect, as far as I understand it. “You” spend most of the time in bizarre states and only once in a 10^^^^^^(…)^^^^^10 seconds chances can reconstruct the next, previous or just different step of a reasonable continuous experience, including all memories “you” “think” about in this moment.

But in my opinion this is overengineered. States not only don’t have to come in order, they don’t have to form a continuous “movie” at all. An infinite amount of “current” moments with all the past and current reality already embedded in is sufficient.

Re: John C. Mather: “There is no first moment of time” (2017)

#79

Post by mistermann »

dudeguy3301 wrote: post #61
anonymousiam wrote: post #44

Earlier quoted context omitted.

"And yet, you've managed to do just that!" How?

lol, some people just 'think' different, like the old macintosh adds...

It is true, but whether it is funny, and whether the Macintosh ads are an adequate illustration, are very different matters.

Re: John C. Mather: “There is no first moment of time” (2017)

#80

Post by sounds »

aasasd wrote: post #76
sounds wrote: post #73

Earlier quoted context omitted.

> if I understand the whole comment right, a curved universe is guaranteed to have an edge, but with a non-curved one it's a toss-up because no one knows what it would look like. A curved universe doesn't "have an edge," I'm referring to Euclidean and non-Euclidean geometry [1]. As in, if the curvature is truly and perfectly zero, then the space-time we live in goes on forever. If it has even the tiniest curvature, t…

> A curved universe doesn't "have an edge" Ah, indeed, quite a brain fart moment from me there, since you explained the structure right in the previous comment. Pondering cosmology while sleep-deprived is suboptimal, I guess. Though now I'm curious about this: > If it has even the tiniest curvature, then it curves back onto itself and is non-Euclidean Would it be possible in theory that the three dimensions are curve…

Just hypothetical 3D curved spaces here, not saying this has any physical reality -

If the X axis curves into Y (i.e. wraps around the Z axis) and also has a slight negative Z component (i.e. to move in a helical fashioin) each of those curvatures would mean a line segment eventually intersected itself.

It's the nature of the curvature: the space is not sheared (like a rhombus), it is curved (like latitude and longitude), which is why the line segment eventually intersects itself.

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