61–70 of 84 posts
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> 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?
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Didn't Gödel prove that you can't prove a theory with its' own ruleset? In physics maths always go haywire durnig phase changes, as gas laws don't apply to liquids, and such.
No, he proved that under existing axiomatic systems, there are some statements which cannot be proven to be true axiomatically, even though they are true; such axiomatic systems are, in his terminology, incomplete. A subtle but important difference.
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One thing I've always wondered is if there's any _interesting_ statements that can't be proved or if they're all kind of self-referential nonsense statements.
A while ago there was a result that relates to materials science: https://arxiv.org/abs/1502.04135
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“On an infinite timeline, everything should occur, forever.” I can imagine scenarios where that isn’t true- maybe the universe cycles through a long loop of states and just repeats that infinitely for example.
Isn’t that saying the same thing but a little differently? In your scenario, everything is re-occurring, forever (obviously beyond our perception)
”The observable universe was once compressed into a volume the size of a golf ball, but that golf ball was only a tiny piece of a universe that was infinite even then.” What a helpful way of thinking about it. I’m surprised I’ve never heard this before. Mind expanding, no pun intended.
> there is no sign of an edge of the universe How is this determined? I would think that the observable universe puts a limit on our view anyway. Is it the redshift receding into infinite wavelengths? Can the instruments even detect this?
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…
> 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 with a non-curved one it's a toss-up because no one knows what it would look like.
Then, when the article says:
> It’s often said that the whole universe we can now observe was once compressed into a volume the size of a golf ball, but we should imagine that the golf ball is only a tiny piece of a universe that was infinite even then.
Does the author essentially mean that the smaller universe still had only a part of it observable? Or am I mixing things up here? In fact, if the universe expanded faster in the early days, I would guess it was less observable than now (even disregarding all the matter getting in the way).
There is no time, only movement. No movement == no time. You can't measure time without movement. If everything in the universe stopped moving, no time would pass. The first moment happened when space was created and something in it changed its position. (Of course, that something is matter, which is just a wave, and a wave by definition is movement... So really, time started when reality started wobbling.)
> So really, time started when reality started wobbling “It’s all wiggles” —- Alan Watts
> "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 into sub-wiggles. Or see it as a subordinate wiggle in a bigger wiggle. But there’s no real fixed rule about it.”
He and Schrödinger would have had a blast together.
> there is no sign of an edge of the universe How is this determined? I would think that the observable universe puts a limit on our view anyway. Is it the redshift receding into infinite wavelengths? Can the instruments even detect this?
On further thought, things redshifting away into the blackness just denote the edge of the visible universe, don't they? Since that's where light has trouble ever catching up with us, instead of being carried away by the expansion. So this isn't quite related to the universe being infinite or not.
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?
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…