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Center of the observable universe

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1097770.  Mon Oct 13, 2014 9:26 am Reply with quote

You're right, it's not Stephen's definition at all. Similarly, flightless is a zoological term that can take on a different meaning in layman's terms. The show has done this a few times; hardwood, softwood, berry, nut, bean, etc.

1097897.  Tue Oct 14, 2014 4:43 am Reply with quote

JamesCC wrote:
I suppose theoretically if one could accurately measure and model every single thing in the universe then one might be able to model back past that point... :) All you'd need is a spare universe or two to contain the necessary computer! :(

Not even then, I'm afraid.

The key phrase in that post is "accurately measure". In order to model the universe with any degree of accuracy, you would need incredibly accurate measurements of the velocity and position of all those sub-atomic particles. Unfortunately, that bastard Heisenberg put the kibosh on that idea back in 1927 so, even with your two-universe-sized computer, you still wouldn't be able to do it :(

1097898.  Tue Oct 14, 2014 4:47 am Reply with quote

JamesCC wrote:
I may be flagilating a deceased equine, but my point (as opposed to my problem!) is that Stephen did not specify 'observable by you', or 'observable by humans'. He simply said 'observable'.

My point is that, with that word used, the answer is wrong. Had the wording been tweaked a little it would have been fine. Had he said 'human-observed universe' then the answer would have been spot on, albeit easier to get correct.

So here's a quibble that Johnny Vegas might be interested in:

If we take the term "observable universe" to mean the universe observable by human beings, then we have to consider the Earth's orbit around the Sun.

The patch of sky observable at any point is defined by the Earth's position around the Sun. Even radio telescopes, which can happily observe during the day, are unable to see through the Sun, so the part of the sky behind the Sun is always unobservable at that time.

Of course, we can observe it at a different time of year, but that implies that, to build up a picture of the "observable universe", one would have to average over all of the sky observable over the course of a solar year.

In which case, the centre of the "observable universe" would indeed be the Sun :)


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