Philosophy Of The Cosmos - Expanding Universe And Light
Tutorial group 3-4pm Thursday.
With reference to the tutorial discussion from the 3-4pm Thursday group regarding the speed of light and velocity, there was apprehension regarding the possibility of objects moving away from each other faster than the speed of light.
In pursuing some further reading, we have encountered in Brian Greene's work, 'The Fabric of the Cosmos', (Camberwell, Victoria: Penguin Books, 2008), an interesting comment regarding that subject. We will quote it here first and then place it in the context of the discussion group's comments.
On page 237, Greene, under the sub-title of the 'Subtle Features of an Expanding Universe' rhetorically asks that:
"if the speed of recession is larger and larger for galaxies that are farther and farther away, doesn't that mean that galaxies that are sufficiently distant will rush away from us at a speed greater than the speed of light? The answer is a resounding, definite yes."
Greene supports this by arguing that:
"galaxies on average, hardly move through space at all. Their motion is due almost completely to the stretching of space itself. And Einstein's theory [special relativity] does not prohibit space from expanding in a way that drives two points - two galaxies - away from each other at greater than light speed."
Now whilst the discussion group was concerned with the example of two galaxies moving farther, and faster away from each at high velocities, it would seem that in the group we were confused because we did not differentiate between movement through, and expansion of, space.
Does Greene's argument clarify the issue we had on Thursday in the 3-4pm at all? - or is this entry jumping ahead of the coursework too far?

jahla.g & jason.a
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Good point. All this is relativity theory, which we'll get to later in lectures. In particular, we'll get to the difference between objects moving away from each other normally and space expanding.
Jason
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Ahh, I see - good to know. I apologise for not being at today's tutorial, but I have to be present for the renovations undergoing at my house today on behalf of my landlord who's in Victoria.
Nevertheless, since reading that quote the other day I've nearly finished Greene's book, and though quite amazing, I'm troubled by the lack of understanding in the work. I've found myself asking all the way through, 'amazing! - but what does any of it mean?'
Although I haven't finished - I've got another 60 or so pages to go. It seems that Greene, though he uses the word meaning, sheds no light on understanding meaning, and thus sheds no light upon the meaning for/of physics. By this I mean (pun intended) -there's doesn't appear to be any translation from search&discovery to meaning and understanding. It seems there is maintained in the work a dichotomy between cosmos and polis. It may be a really trivial point, but I'm not sure - I am not totally satisfied with purely reading about discovery.
Are such questions regarding meaning, and, as my friend puts it, the 'meaning of meaning' (in view of physics), brought to consideration later in the course?
Nonetheless - cheers for the response!
jason.a
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There will probably be a bit on truth, which will touch on meaning, but there won't be much. And there's a recurring theme about our place in the Universe, but although it's recurring it's mostly implicit and we won't really be saying much about it. Most of the course will be physics, plus goofy topics like extraterrestrial life. This is partly a philosophy course, but mostly a cosmology course. Maybe unsatisfactory, but everything's a compromise!
Jason (the other Jason)
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Meaning is just a nagging question of all my studies. - Nonetheless, once I've finished Greene's book, I likely have some more cosmologically orientated questions to ask.
jason.a (the same jason)

Thanx for putting this post up and addressing the unresolved discussion from the tute! i spoke to dayal and he gave the same answer, and consequently, it seems that things will start disappearing from the sky, but obviously not for a long long long long time. I'm really looking forward to learning relativity now because i feel like alot of things will make a whole lot more sense!
cheers,
~sharmila