igosaur

As Carl Sagan said, "The Cosmos does not have to conform to our expectations of it"

The Igosaur Dirty Soap Bubble Fame at last!!!

The universe, as I understand it, is a closed system. The reason that matter cannot drift outside is that there is no outside for it to drift into, i.e. matter can only exist in the space that was created along with it. The best analogy I can come up with is that of a dirty soap bubble. The bubbles surface itself is space and all the dirt and particles trapped in the soap/space are matter. The bubble can expand and expand but the matter/dirt is always on the surface and can never escape. Now imagine this for the universe but add an extra dimension. I am now ready to be shot down in flames

You're quite right, using this example it should be no bigger than 760,000 light years across. This would then mean that objects are moving apart from each other at a speed that is at least aproaching the speed of light. Yes, or at least all the matter that was created. When I said round and around I meant that if a photon, or anything else for that matter, were to travel in a straight line for long enough it would eventually arrive back at its starting point. Surely the Universe is expanding at the same rate throughout, so, an observer on the Earth would see the same rate as an observer 10 billion light years away. And anyway, isn't the speed of light the end of the line?

The surface of a sphere does not have a centre.

So basically it's like a closed system where no matter how fast or long light travels it can never escape. It just goes round and around getting more and more stretched as the Universe expands further.

The problem probably arises because in this scenario I am imagining the Universe as a huge explosion at a point in an infinite void of space. 380,000 years after this explosion the first light shone. Now, imagine that somehow, I'm there in a spaceship and I'm surrounded by particles that will some day make up the Sun, Earth etc. I decide to have a race with the furthest photon of light in this small, brand new Universe to see who can get to the ultimate location that the Sun now occupies. My spaceship can only drift with the particles that surround it but the light of course, travels at the speed of, well, light. After about 13 billion years I find myself far, far away from my starting point, orbiting the Earth. How is it then that I can observe the light I decided to have a race with? Surely the furthest away it could possibly have been is 380,000 light years, so, after 13 billion years how is it that I have arrived here before the light?

The MBR, I'm reliably informed, is light emanating from when the Universe was just 380,000 years old. We are now just picking up this light in the form of microwave radiation. However, surely when the light first started its journey the Universe was much, much, much smaller than it is today and of course, the matter that would one day make up our solar system and the detectors that see this radiation were part of it. How is it then that over 13 billion years later we can 'see' this light? Surely by this time the light from this distant era of the Universe would have long since past the position in the Universe that we now occupy. I know that I am probably missing a fundamental point about the shape of the universe and inflation etc. but if someone could help me expand my consciousness on this point I'd be really grateful!!

One of the most scientifically accurate films I've seen

Yes. Quite right

I must confess, I looked the numbers up and found a puzzle website. That was their answer. Very now..

I think the heat generated from this thread would be sufficient to supply energy to a medium sized town! I seem to remember a special episode of 'Beyond 2000' (ahh, those were the days) where they were looking into the practicality of constructing huge orbiting solar power stations that could convert electrical energy into microwave then beam that at a base station on Earth where it could be converted back to electricity with an efficiency of 85%

Would I be right in then thinking that any further water added to the surface would then exist as liquid and not add to the atmosphere?

Even though it would be impossible to measure, the pressure must increase to some degree, even though it may just be a local effect. After all, if you left enough bowls of water out, at some point it would be measurable. But I take your point and you are of course quite right That sounds about right. The atmoshpere of Mars is relatively thin, atmospheric pressure on the surface varies from around 30 Pa (0.03 kPa) on Olympus Mons to over 1155 Pa (1.155 kPa) in the depths of Hellas Planitia, with a mean surface level pressure of 600 Pa (0.6 kPa). This is less than 1% of the surface pressure on Earth (101.3 kPa). -- Wiki --

Therefore raising the atmospheric pressure of Mars ever so slightly thus increasing the temperature needed for water to evaporate.

And then the water that's left, using the Martian example, would then freeze. But then what about the water vapour in the thin atmosphere, would that then rain back as a fine frozen mist I wonder? I wish I could go there and find out

1) 1 2) 11 3) 21 5) 1211 8) 111221 13) 111222211

I stand corrected yet again Let's say that on a warm sunny martian day it would boil away, or, it was a bowl of warm water it would evaporate before it froze.

This is very true. However, the pressure is so low that if you were to place a bowl of water on its surface it would boil/evaporate away.

Presumably, this is why there are no lakes or rivers left on Mars. Since the atmosphere became stripped away by the Solar winds, the pressure dropped and hey presto. What didn't freeze into the surface simple evaporated away.