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Physics, Astronomy & Cosmology / Re: How can Dark Energy make the Universe expand at faster than light speed?
« on: 28/02/2018 15:10:52 »3
Physics, Astronomy & Cosmology / Re: How can Dark Energy make the Universe expand at faster than light speed?
« on: 26/02/2018 20:41:04 »Quote from: AzharI've read quite few times that nothing can travel at a speed greater than speed of light.
This is probably a case of "sloppy" language. What SR says is that nothing can be accelerated from subluminal to superluminal speed. (Nit-pickers of the world unite. )
This right there actually explains it. Nit-picking is good
Physics is all about getting close to as much accuracy as possible.
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Physics, Astronomy & Cosmology / What is spacetime made of?
« on: 26/02/2018 18:39:17 »
Hello,
I heard recently that spacetime is "granular". Leaving time aside for a minute, what exactly is "space" made of? What does it mean when we say "space" anyway? Is space formed by all the matter/non-matter particles and "sum or collection" of those is space? How is it granular?
Thanks in advance!
I heard recently that spacetime is "granular". Leaving time aside for a minute, what exactly is "space" made of? What does it mean when we say "space" anyway? Is space formed by all the matter/non-matter particles and "sum or collection" of those is space? How is it granular?
Thanks in advance!
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Physics, Astronomy & Cosmology / Re: How can Dark Energy make the Universe expand at faster than light speed?
« on: 26/02/2018 18:32:27 »galaxies are moving away at a speed greater than speed of light
I agree that this can be a bit confusing. What @jeffreyH is saying is that the space itself has expanded, making the galaxies become further away; they've not actually moved though; they are just separated from us by more intervening space, making them appear to be retreating from us; granted they are moving, but some of the apparent movement is the expansion of the Universe.
So does this mean that when they say "galaxies are moving away with speed greater than speed of light" what they mean is that the light that SHOULD HAVE ALREADY been able to reach those galaxies since it had been travelling towards them, HAS NOT reached them becauses galaxies have moved away (expanded space)?
I feel like the language used to describe this seemingly contradictory nature of things is a bit confusing for a layman like myself. To me if nothing cannot travel faster than speed of light then space shouldn't be able to expand at speed greater than speed of light. No?
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Physics, Astronomy & Cosmology / Re: How can Dark Energy make the Universe expand at faster than light speed?
« on: 26/02/2018 18:03:07 »
Thank you for the response. I'm not sure my question is answered though.
If nothing can travel at a speed greater than light then how can the statement "galaxies are moving away at a speed greater than speed of light" be true? The second statement seem to contradict the first statement and I'm curious to know which one of them is true.
Thanks.
If nothing can travel at a speed greater than light then how can the statement "galaxies are moving away at a speed greater than speed of light" be true? The second statement seem to contradict the first statement and I'm curious to know which one of them is true.
Thanks.
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Physics, Astronomy & Cosmology / How can Dark Energy make the Universe expand at faster than light speed?
« on: 26/02/2018 17:48:55 »
Hello,
I've read quite few times that nothing can travel at a speed greater than speed of light. I think this is an upper limit proposed by Einstein's theory of special relativity.
However I have also read that universe if expanding at speed greater than speed of light. I think we call it dark energy. My question is, these two statements seem to be at odds with each other. How do you reconcile these?
Thanks in advance.
I've read quite few times that nothing can travel at a speed greater than speed of light. I think this is an upper limit proposed by Einstein's theory of special relativity.
However I have also read that universe if expanding at speed greater than speed of light. I think we call it dark energy. My question is, these two statements seem to be at odds with each other. How do you reconcile these?
Thanks in advance.
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Physics, Astronomy & Cosmology / How does dark matter interact to shape galaxies?
« on: 07/01/2018 20:49:08 »
Hello all,
Newbie here with no background in science whatsoever.
I've a question regarding dark matter. I understand that we know dark matter exists because it causes to affect how galaxies are shaped outerly. But yet we are not able to detect it using various means.
My question is, if it doesn't interact with anything we know so far and hence we have not been able to detect then how is it interacting to form the shape of the galaxies? After all IT IS interacting with the mass/gravity within galaxy to have an affect in their shape.
Thanks in advance.
Newbie here with no background in science whatsoever.
I've a question regarding dark matter. I understand that we know dark matter exists because it causes to affect how galaxies are shaped outerly. But yet we are not able to detect it using various means.
My question is, if it doesn't interact with anything we know so far and hence we have not been able to detect then how is it interacting to form the shape of the galaxies? After all IT IS interacting with the mass/gravity within galaxy to have an affect in their shape.
Thanks in advance.
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