Discussion
I'm with you on the confused thing.
http://www.theguardian.com/science/2013/oct/23/mos...
time (edit) distance is measured in light years (is this where my understanding falls down?!), how can the universe be 13.1ish bn years old when there is something 30bn light years away?
Also, if this group of stars is a star factory, surely it's pumped out stars on the opposite side to us, so there's an additional 30bn light years of stars the other side, thus there's 'stuff' 60bn light years away? :smallbrainexplodes:
http://www.theguardian.com/science/2013/oct/23/mos...
Guardian article says said:
The ancient group of stars lies 30bn light years from Earth... Analysis of light coming from the galaxy showed that it formed only 700m years after the big bang, or 13.1bn years ago, making it the oldest and most distant galaxy known.
If Also, if this group of stars is a star factory, surely it's pumped out stars on the opposite side to us, so there's an additional 30bn light years of stars the other side, thus there's 'stuff' 60bn light years away? :smallbrainexplodes:
Edited by warp9 on Thursday 24th October 09:39
Distance is measured in lightyears, not time. However, the size of the universe is not static and the rate of expansion of the universe is not static (or even linear). So light can have travelled for 10bn years (for example) but the object it travelled from can now be much more than 10bn lightyears away because the universe has expanded significantly in those 10bn years.
k is that although nothing can exceed teh speed of light and the universe is 13.7billion years old it has a radius greater than 13.7 billion light years. This is possible because in the early stages of the big bang everything inflated.warp9 said:
If time (edit) distance is measured in light years (is this where my understanding falls down?!), how can the universe be 13.1ish bn years old when there is something 30bn light years away?
If we stand face to face and you step 1 metre back, you are 1 metre away from me.If we stand face to face and you step 1 metre back AND I step 1 metre back then we are then 2 metres apart, despite the fact that you (and me) only moved 1 metre.
Dracoro said:
If we stand face to face and you step 1 metre back, you are 1 metre away from me.
If we stand face to face and you step 1 metre back AND I step 1 metre back then we are then 2 metres apart, despite the fact that you (and me) only moved 1 metre.
Good explanation, that helps. Don't the figures in the article suggest that the universe is expanding faster than the speed of light?If we stand face to face and you step 1 metre back AND I step 1 metre back then we are then 2 metres apart, despite the fact that you (and me) only moved 1 metre.
warp9 said:
Good explanation, that helps. Don't the figures in the article suggest that the universe is expanding faster than the speed of light?
Has in the past, isn't now (see the inflation bit of the picture above). Although it is difficult to measure "speed" or "distance" if the things you use to define those terms are changing.ewenm said:
warp9 said:
Good explanation, that helps. Don't the figures in the article suggest that the universe is expanding faster than the speed of light?
Has in the past, isn't now (see the inflation bit of the picture above). Although it is difficult to measure "speed" or "distance" if the things you use to define those terms are changing.Also, bringing up my second point, is there 30bn light years of universe on the other side of this cluster of stars found?
warp9 said:
So how can we rely on our current measurements of speed/distance?
Also, bringing up my second point, is there 30bn light years of universe on the other side of this cluster of stars found?
By applying knowledge of the rate of expansion of the universe.Also, bringing up my second point, is there 30bn light years of universe on the other side of this cluster of stars found?
I don't know. Is the Universe "closed" like the surface of the earth - so if you go far enough you end up back where you started? Or is it "Open"?
A light year is a measurement of distance, not time. So what a light year actually is, is the distance travelled in a year at the speed of light. I think it is often used because it is easier than describing something that is a light year (and any subsequent number of them) away as being 5.88 trillion miles from Earth.
Hooli said:
On a similar subject. What is at the 'end' of the universe? except for a restaurant of course. What happens to light or matter when it passes the restaurant as well?
That model of astrophysics is no longer popular the new proposed end of the universe is heat death.Wikipedia said:
The heat death of the universe is a suggested ultimate fate of the universe in which the universe has diminished to a state of no thermodynamic free energy and therefore can no longer sustain processes that consume energy (including computation and life). Heat death does not imply any particular absolute temperature; it only requires that temperature differences or other processes may no longer be exploited to perform work. In the language of physics, this is when the universe reaches thermodynamic equilibrium (maximum entropy). The hypothesis of heat death stems from the ideas of William Thomson, 1st Baron Kelvin, who in the 1850s took the theory of heat as mechanical energy loss in nature (as embodied in the first two laws of thermodynamics) and extrapolated it to larger processes on a universal scale.
Hooli said:
On a similar subject. What is at the 'end' of the universe? except for a restaurant of course. What happens to light or matter when it passes the restaurant as well?
I'm in that restaurant (yes, we have the internet too 
) waiting for everyone to get here. When you get here, I can show you what happens to the light as it passes As for what's at the end, it's just a big END sign, bit of an anti-climax really.
Hooli said:
On a similar subject. What is at the 'end' of the universe? except for a restaurant of course. What happens to light or matter when it passes the restaurant as well?
As the Universe is now consdieerd 'flat' and infinite, there is no end. But as detailed above, as we lpook futher away, we also look back in time as light speed is finite. There comes a stage when we can look far enough away to see the first Light Producing Objects in the Universe, but we can see no further, because there were no LPOs before that. So the Universe has a visible limit, a globe around us with a radius of about 14 billion light years.The furthest we've seen so far was formed about 700 million years after the Big Bang:
http://www.universetoday.com/105694/taking-measure...
JOhn
ash73 said:
Yes it is, any galaxy with a redshift greater than 1.4 is currently moving away from us (or more precisely the space between us is expanding) faster than c.
OK, I'll bite - but I didn't think it was possible to travel faster than the speed of light? (expect QI WAH WAH klaxon to go off!)You're right, ash, about expansion, but your magnitude is wrong. I fear you ignore Special Relativity!
If the velocities in opposite directions (U and W) are significant fractions of C, then their relativistic seperation velocity V = (U - W)/(1 - UW/C^2). Thus, you will note, V can never be more than C.
John
If the velocities in opposite directions (U and W) are significant fractions of C, then their relativistic seperation velocity V = (U - W)/(1 - UW/C^2). Thus, you will note, V can never be more than C.
John
Edited by tapkaJohnD on Friday 25th October 16:24
Edited by tapkaJohnD on Friday 25th October 16:25
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