AIBU to question the popular belief that there are more stars in the sky than grains of sand on earth?

[Tryingtryingandtrying]

How can this possibly be true? Tbh I'd question if there were more stars than grains of sand on my local beach? I've read a bit around it and still is impossible for me to comprehend. Any other facts or theories that just don't make sense to you?

NotDavidTennant

I don’t believe the laws of the Universe are constrained by what we imagine. We can imagine anything we like. But that doesn’t mean the things we imagine are laws. I am not saying things we can prove aren’t true because we don’t fully understand them; I am saying some things haven’t been demonstrated to be true.

The idea that the universe (largely composed of nothing) is expanding into ‘nothing’ is not fully understood by anyone in this age of scientific enquiry.

@AStudyinPink

Space itself is expanding.

But the same questions stands: expanding into what? If it has a current ‘finite’ amount, there must be something separating the nothing we are describing expanding from the nothing into which it is expanding. And that means - in any case - that we must add the ‘nothing’ ‘outside’ the ‘known’ universe to the ‘nothing’ into which it is expanding, the entire becoming what is ‘known’.

And thus, since nobody can explain that paradox, we know... nothing.

I like to think of a balloon that's being blown up. That balloon is "spacetime" - and we're woven into a minuscule speck within its fabric. What's outside it? Something that's utterly beyond my comprehension. There might be something there, or there might be nothing there - or there might be a blend of the two within which the words "something" and "nothing" have no meaning. That's how I see it, anyway.

DodoApplet

Right. So like I say, we don’t really know. I have no issue with people’s theories, but that’s what they are.

Whenever I want to feel insignificant, I like to look at the Hubble Ultra Deep Field. Click on upload.wikimedia.org/wikipedia/commons/0/0d/Hubble_ultra_deep_field_high_rez_edit1.jpg, zoom in, and marvel at the fact that the tiniest dots in this image are galaxies with hundreds of billions of stars - and that this picture represents one twenty-sixth-millionth of the sky.

The idea that the universe (largely composed of nothing) is expanding into ‘nothing’ is not fully understood by anyone in this age of scientific enquiry.

This is just semantics. You're treating the phrase 'expanding into nothing' as meaning 'expanding into a thing called nothing' and then you can ask 'what is this nothing it is expanding into?' But the people saying it is 'expanding into nothing' mean 'it is not expanding into anything'.

Expanding into something makes sense if you imagine a bubble in a glass of water that takes up a finite amount of space and as it expands gradually takes up more of the surrounding space. But in the case of the expansion of the universe, the universe is not expanding into surrounding space, it is space itself that is expanding.

@iklboo
The Earth is a tiny, tiny planet in a tiny solar system, on a small arm of a small galaxy which is one of millions of other galaxies. All those suns, planets, moons etc will appear as a 'star'.
Apart from a handful of planets in our own solar system, no other planets or moons will appear as "stars".

This is my favourite vid to understand the scale of it all. Ds loves this one!

NotDavidTennant

I don’t think it semantic. I don’t think you can argue that a finite Universe is expanding (because the space of which it is composed is expanding) without there being a further ‘space’ into which it expands. And that isn’t semantic. Nothing about this discussion is semantic.

The reality is, we don’t know what may or may not exist beyond the entity we call ‘the Universe’.

I don’t think you can argue that a finite Universe is expanding (because the space of which it is composed is expanding) without there being a further ‘space’ into which it expands.

Well you can argue it, and people who understand these things better than you or I do argue it.

But I agree that we don't know for absolute certain what, if anything, exists beyond the bounds of this universe.

Well you can argue it, and people who understand these things better than you or I do argue it.

Well, sure. They can say that. But until they provide an argument that makes sense, I’ll continue to say that that one doesn’t.

One thing that always blows my mind is that it's impossible to write out all of the digits in a googolplex (1 x 1010100).

Even if you could put 1 digit on every atom in the universe there wouldn't be enough atoms to complete the number.

And that's not even the biggest number out there. Trying to understand Graham's number or Kruskal's TREE(3) just make me want to hide under the covers.

@AStudyinPink

DodoApplet

Right. So like I say, we don’t really know. I have no issue with people’s theories, but that’s what they are.

Oh, I think I'd put it even stronger than that. Even having a "theory" implies that we've managed to create a model that explains something we've observed, after which we use that model to try to predict something that we haven't yet observed. Then if we get it right, we jump up and down with glee and publish papers about it. If we get it wrong, we mutter "sod it" and start again... but then, how can we observe something that by definition lies beyond our universe?

I don't see how we can know. I find it mind boggling enough to think that every star we can see is a 'sun', with (mostly) its own planetary system around it.

@NotDavidTennant

I don’t think I am missing the point. I think you are saying something that makes no sense and you don’t understand any more than I.

Lots of things about physics don't make intuitive sense. How can a photon be both a wave and a particle at the same time? To our intuition that seems impossible, but all observation says that is exactly how photons behave and we can explain this perfectly with maths even if we can't imagine it.

Likewise we can perfectly well describe the expansion of the universe mathematically without needing a medium for the universe to expand into, even if we can't imagine what that is actually like.

There is no reason that the physical laws of the universe should be constrained by what we can imagine, anymore than they should be constrained by what a chimp or an orang utan can imagine. We are just glorified apes after all.

👌🏻👌🏻👌🏻👌🏻

The double slit experiment is fascinating.

but then, how can we observe something that by definition lies beyond our universe?

I don’t know.

A couple of observations.

There is a lot of confusion in popular accounts of cosmology between "the universe" and "the observable universe". The latter is everything we can see, and is finite in extent. The furthest things away that we can see are approximately 45 billion light years away now. The rest of it, we don't actually know - we can't see it. However, if you make the assumption that the laws of physics aren't different elsewhere (and they don't seem to be different anywhere in the huge region we can see) it leads to three possible models for the whole universe - two are infinite in size, and one is finite but closed, so it doesn't have edges. Detailed observation matches one of the infinite sized ones, but we can't strictly rule out a really, really big finite one (more than a trillion light years travel to get back where you started from, if memory serves).

On the subject of "space expanding", the only really rigorous explanation is the Friedman equations and a few years of study to get the degree level knowledge you need to understand what they actually say. Anything in words (even words from experts) is wrong in some sense, including "space is expanding". But it's a hell of a lot less wrong than most other words. "What's it expanding into" is one of those places where the explanation isn't particularly satisfying. It isn't expanding into anything - it's already infinitely big, so asking what's beyond infinitely far away makes no sense. But still the distances between distant galaxies grows. In some senses it would be easier to just say that distant galaxies are moving apart rather than say space is expanding, and because space appears to be infinite in extent that can go on forever without running into edges (because there aren't any). But if you say that, people just ask a different set of questions that are difficult to answer without dumping a physics course on their heads. There's no really good solution to it.

So yes, at least in some senses, space is expanding. But it isn't expanding into anything because it already is everything.

SpeverendRooner

Can I ask what your qualifications are to tell people what they need to have done in order to ‘understand’ these ‘more plausible’ explanations? I’m not saying you’re wrong, just curious.

It isn't expanding into anything - it's already infinitely big, so asking what's beyond infinitely far away makes no sense.

Because to me, something already infinitely big can’t be getting bigger, because ‘bigger’ as a concept presupposes a previously measurable size. 😂

But I’m not a scientist. I’m just a person waiting for a scientist to make sense.

Scale of the universe things on YouTube blow my mind. Watch onex

A few "Infinite Monkey Cages" cover these things.

My ghast was flabbered at the idea that the distant stars are accelerating and will eventually be further away than it's possible for the light to reach us from them. They will effectively "disappear" over the horizon and become invisible to future generations.

Which was discussed here: www.bbc.co.uk/programmes/p08dy6ym and the suggestion that we record what we see for future generations who will have to take it on trust went impressively undebated .....

en.wikipedia.org/wiki/Future_of_an_expanding_universe

@AStudyinPink

SpeverendRooner

Can I ask what your qualifications are to tell people what they need to have done in order to ‘understand’ these ‘more plausible’ explanations? I’m not saying you’re wrong, just curious.

A physics degree and a stack of textbooks about two feet high.

Obviously you don't need a particular qualification to talk about and understand anything, just the learning. The point is that physicists communicate about this stuff between each other in mathematical terms. It isn't just for fun. It's genuinely the only method we've got that isn't hopelessly ambiguous. We can make attempts to explain stuff in words, but if it were completely accurate we wouldn't use mathematical tools it takes us years to learn, we'd just use words and save ourselves a lot of pain.

@PlanDeRaccordement

The universe is not infinite. But there are infinite universes.

You can theoretically travel faster than the speed of light because the speed of light is not a constant (Einstein was wrong). The speed of light changes depending on gravitational fields. They discovered this by watching black holes.

Time is also not a constant. It flows at different speeds depending on how fast you travel AND the gravitational fields you generate and travel through.

NASA is doing warp bubble experiments using magnetic fields to compress space time in front of a laser, and then expand space time behind it. The lasers light particles are just proxies for future starships. Anyway, they can get lasers to go faster than light. All we need is a huge energy source that can move a whole starship that fast AND keep carbon lifeforms alive otherwise it will be robot drones we’ll be sending out to explore the galaxy.

In addition, wormholes do exist, these are rifts in time and space and can transport particles from one part of universe to another part of the universe faster than light either by slowing down time or making it go backwards. Or even hop to another universe. We even know how to make one by putting magnetic arrays in orbit of a black hole. No one has gone through one yet, so no one knows where they go. We don’t even know if we have the right spaceship materials and internal life support technology to survive such a trip.

Number is stars to grains of sand. Who knows. Probably more grains of sand because a lot of stars have sandy planets around them. Too, if you count cosmic dust....that’s outer space sand and is everywhere.

But our descendents will hopefully get there one day.

Reading this is like giving my brain a lovely cuddle and stroking it 💕 it’s the most beautiful post I’ve ever seen on MN

SpeverendRooner

Fair enough. But until I hear something sensible in words I will assume you are all very confused. 😂

many 'stars' you see are actually galaxies full of millions upon millions of stars... there are a billion stars in our milky way alone. It's hard to wrap your brain around but very real