Recent content by Saddlestone

Thank you DaveC426913, I think you've captured my question, and brought the thread back on track. I also had in mind that any particle has an uncertainty in its position and therefore space-time must exist where ever the particle might exist, even though it may never have actually been there...

That's an interesting perspective on the acceleration and decceleration needed to achieve the round trip in 1 year of ship time. I recall seeing in a few sci-fi films (or maybe in a book?) that total immersion in a fluid greatly increases the tolerance to high-g forces. The fluid needs to...

Take a look at the lyrics to Queen's song '39, eg at http://www.elyricsworld.com/39_lyrics_queen.html Anyone know if there are any other pop songs about time dilation? Was Brian May showing off his Astronomy knowledge in a subtle way?

The significant events in the early universe, eg see: http://en.wikipedia.org/wiki/Timeline_of_the_Big_Bang are measured in very small intervals. For example, at 10>-32 seconds after the big bang the Inflationary Epoch era ended, then the Quark Epoch lasted from 10>-12 to 10>-6 seconds, etc...

By "an empty universe" I take this to be a universe with no matter in it. I'm assuming that if you know the average density of the universe, then you can calculate its expansion rate. How fast would an empty (of matter) universe expand compared with our universe which has some amount of...

By "full of space-time" I mean that every point in the universe exhibits properties of space-time. By "almost empty" I mean that most points in the universe are devoid of matter. I'm sorry that I don't have mathematical ways of expressing this. It just seems to me that the relationship...

It seems to me that the universe we inhabit is ALMOST empty of matter, ie the average density of matter is very low. But it is FULL of space-time. Therefore there doesn't seem to be a strong correlation between matter existing and space-time existing. Although, as you say, you can't separate...

I can understand the inter-connection between matter and space-time in the volumes of space where matter exists. But how about the vast volumes of space where there is no matter. Clearly space-time exists in these volumes. As far as I can see matter needs space-time, but space-time doesn't...

I'm thinking of the natural speed limit of say a rocket leaving earth, which is limited to c. When in the development of the universe did this speed restriction come about? Has it always been limited to the speed of light and does it depend on light itself (ie photons) existing? Has c...

Ok I think I get that. Up to a few years ago the view was that the expansion of the universe would slow down and it would eventually start to contract, leading to a Big Crunch. Would it have only been the matter in the universe that would have collapsed inwards, or space itself?

Ok I see that. But what is the shape of the new space-time? Is it an expanding sphere, or is its shape dependent on the perhaps non-uniform outer surface of the expanding matter. I'm trying to understand the relationship between the shape of space-time and the shape of the matter that exists...

Space expands and carries matter into it. So just after the big bang, as the ultra-hot matter was starting to expand, was an expanding space-time sphere being created in anticipation of matter filling that newly created space?

As the universe expanded after the big bang it was expanding into nothingness, ie even the fabric of space-time itself didn't exist. How far ahead of the expanding matter was space-time being created for it to expand into?

I guess what concerns me is that statements are made about events happening at certain times in the early universe without reference to the observer who is measuring the time. Einstein would turn in his grave over such sloppiness! On a slightly different point, which Einstein would have found...

I didn't think they were trying to re-create the universe, simply the conditions that applied at the time. The question is still valid - doesn't the existence and influence of the current universe negate any attempt to create the original universe's starting conditions?