Who says it's a closed system?

It's either expanding into something or something is being compressed somewhere. My 30cm ruler doesn't seem to have expanded in the last few weeks, although I can't be sure how big it was before I got it out the stationary cupboard (stationery).

Which leads to the real truth, everything only really exists as you see it. Our definitions of the universe will die with us.

Most people seem to be treating Einstein's theories as if they were immutable laws of nature. They are not. They are just a set of mathematical equations that we can use to describe some of the things that we see around us.

These equations do not work at the sub-atomic level. I strongly suspect that they also don't work on the very large scale either.


Don
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If humans aren't agency for knowledge and there is an immutable physical truth to reality that goes beyond our perception, how come we have to think this stuff up before we go looking to see if it's true? Science has long since stopped discovering stuff and really only prooves what our imagination can concieve.

How very handy.

Is this emperical or just very handy?

Because on the face of it it sound like irrational straw clutching to me.

I'd be happy to have the proof, if it is in a language I can understand.

I just found out that marine scientists discovered 32 new species of sea horse over the past few years. Did the scientis just make that up?

OK, in an attempt to explain as I understand it:

Imagine living in a 2 dimensional world. So everything was completely flat, you have no concept of height at all. You couldn't perceive it at all, it makes no sense to your 2D mind.

If objects do have a 3rd dimension/height then you'd be unaware of this as you'd only see or know about the other 2 dimensions.

Now if an object in your flat world lifted 'up', then it would completely disappear from your world/POV as it would no longer exist in your 2 dimensional universe as you understand it, as this mysterious 3rd dimension doesn't make sense or really exist to you.


Back to our 3 dimensional universe, take a star, the gravity pushing all the particles together is stopped by the hot gas inside which is trying to push everything away in a big explosion (this is like our Sun), the balance of these two forces keeps everything in check for the duration of the stars life. But if the mass is much higher then the greater the resultant gravity is heavy enough to overcome this electron force and it's the nuclear force inside atoms that stops this crushing force of gravity, this is a neutron star (atoms are mostly full of space, but the nuclear force the surrounds them stops atoms passing through other atoms, stopping you walking through walls). But if the star is so super massive then this nuclear force propping up the star isn't strong enough to fight of the squashing of gravity, it then squashes to 'nothing' but the effect of where it was is still felt as a black hole.

So all that stuff has vanished, no way to get to it, it has no size at all any more, but it was once several times larger than our whole solar system but now it's gone.

Now back to our 2D universe with your 2D self encountering a 3D object, if the mass of the big star has moved 'up' to a dimension that you can't perceive it any more, it's completely disappeared, and in addition if you were caught up inside that collapse and somehow survived then you'd not be able to detect the rest of the universe from which you came as it is now also in a dimension that you can not perceive or get to, you are now effectively in a new universe all of your own and there are no others.

You would be able to perhaps theorise how big your new flat universe is from your POV, and possibly determine when it came into existence, but you've no real way to determine how big it is relative to the other one or anything else that you could theorise as there's no ruler that would be able to measure the different dimensions required, one isn't relative to the other.

If your new universe expanded, you may ask 'into what is it expanding' but from everyone else's point of view in the universe you left behind, you were squashed and disappeared to nothing.

So take our 3D universe and imagine being confronted with additional dimensions, you've no way of knowing they're there or how 'big' they are and vice versa.

As a PHer, I should probably say "MTFU" or similar, at this juncture. But, you'd probably hunt me down and kill me.

Actually there is no "before" the big bang as this would imply time, which started at the point of the big bang.

S

At which point you're faced with the exact same question, just now concerning the other something rather than our something.