Starlght

[ll_billym]

If the universe is infinite / wraps around on itself why is the sky at night only pinpricked by stars not completely bright?

There must be a star everywhere we look in the sky, even if it is incalculably far away......  the light from that star must reach us as light will travel for as long as there is nothing in the way........

[janesmythe22]

MargeB-No matter what they say, you're right. Singularity simply doesn't behave. And then again 'something out of nothing'.

[Clanad]

Thanks, II_billym, for the question and the opportunity to discuss it...

[georgit79]

MargeB- thanks for having faith in me, but I wouldn't have got anyone yesterday, the state I was in. Was asleep outside in my hammock for most of the afternoon, then watched Scarface!

Ruined today as I got up at 4.30am to drive back down to London....anyway, in answer to the question..the universe is a huge, mysterious thing...and I haven't a clue what I'm talking about. Wake me up later and ask me then.

[georgit79]

Feeling better now...have just read back through the thread, and MargeB, I do get you. What's not to get?

[MargeB]

hi georgi,

well, I think I was misunderstood on one count and totally missed on another. "Not having a beginning in time" does not mean "You go back forever." It means that time did not exist until that event.

The one that was missed was that Relativistic approches to the spacetime do not apply to what occurred to the singularity at the very "start" of the universe. One has to be very very right to even be half justified in ridiculing anothers post (per Clanad), lucky I'm a nice guy and didn't slap him down for the schoolboy error. :-)

It's all just a larf.

[MargeB]

The basic premise of his was that you start with common sense principles and apply them to the the fundamentals of the universe. Big, big mistake.

Space and time are not even fundamentals of the universe...

[georgit79]

There's no arguing with some people though...hhmmph.

I just look for simple answers- like my one regarding the moon (a bit further up the main Science page).

[Clanad]

So, MargeB, it appears you want to argue about an amount of time less than 10^43 seconds... the smallest measurement of time that has any meaning... Planck time. No smaller division of time has any meaning. With in the framework of the laws of physics as we understand them today, we can say only that the universe came into existence when it already had an age of 10-43 seconds. Within the same framework of the laws of physics we can neither measure nor discern any difference between the universe at the time it first came into existence and the universe anything less than 1 Planck time later.

The estimated age of the  (Everything that exists anywhere) Universe (4.3 � 1017 s) is 8 � 1060 Planck times.
 Is it possible that you don't do a very thorough job of explaining what you mean?  An example is your statement "...space and time aren't even fundamentals of the universe"...Exactly what do you mean by that?  Perhaps if I understood your intent we might even agree... but the statement, as it stands, doesn't make a whole lot of sense...

[MargeB]

That's my point, Clanad. In the quantum world very little makes sense, it is so fundamentally different from the world of spacetime relativity that we know.

Something is one state or the other, not both...

Information can travel only as fast as the speed of light..

Observation alone cannot fundamentally change a quantum state...

When something moves from one place to another, it has to exist in all the places in between...

Common sense? But none of these statements are true in the quantum world. Before the Planck era is up, this is the ONLY world that exists. There isn't even mass. There is no spacetime.

And spacetime, as I made perfectly clear, is not a necessary consequence of this quantum state. The universe does not have to have spacetime.

"Making sense" is out of the question at the beginning of the universe, in the centre of Black holes, or at the very very small subatomic level. Read any decent treatise on quantum mechanics. Your head will shake very hard.

[MargeB]

To quote you:

" it appears you want to argue about an amount of time less than 10^43 seconds... the smallest measurement of time that has any meaning... Planck time. No smaller division of time has any meaning. With in the framework of the laws of physics as we understand them today, we can say only that the universe came into existence when it already had an age of 10-43 seconds. Within the same framework of the laws of physics we can neither measure nor discern any difference between the universe at the time it first came into existence and the universe anything less than 1 Planck time later."

This is nicely put, not the explanation I would choose personally. 'The laws of physics' include quantum mechanics, even if these laws are supposed to apply to the Macro world around us. Since the laws of physics apply everywhere at all times, you cannot say that the laws of physics are applicable in the Planck era. It simply doesn't make sense. You don't even have separation of the fundamental forces: they are the same thing.

The irony is that we no pretty much nothing about this time (until we come up with a Grand Unified Theory at least), and yet we need to know a lot about it in order to say with confidence that the universe does not go back forever into infinity, or why the constants are set as they are.

The estimated age of the  (Everything that exists anywhere) Universe (4.3 � 1017 s) is 8 � 1060 Planck times.

[MargeB]

Ignore that last paragraph (carryover).

Oh, by the way, I refer to the universe, definitely not the Universe. That is, our universe as we know it, stuff around us, came from Big Bang, etc. Universe, being everything may be 20 zillion other universes (Rees calls this the multiverse). Perhaps the Universe is a vacuum, and our universe just popped out of it, just like particles do in the vacuums of our universe. Perhaps a Black Hole in the Universe gave rise to our universe.

I just don't reckon (this is very unscientific) that the universe popped out of just nothing. I like best the idea that somehow two other universes interacting were involved. Maybe one day we'll know. We'll look back on this conversation, laugh politely, and change the subject...

[Peter Pedant]

well I learnt soemthing!

Yup this is a straightforward Olber's paradox,

however I hadnt understood the cancellation bit until I read Clanad's contribution.....thanks

[-=BigD=-]

Worms,

can,

of.

ll_billym, i suggest reading the 1st chapter of "a brief history of time" and then sitting back, relaxing, let the boffin's quible over semantics, and wait for some uber-boffin to come up with a complete theory (or would that be meaning?) for everything.