21–30 of 106 posts
What is the "GTC"? The article doesn't say.
It appears to be the Gran Telescopio Canarias.
How can the further Galaxy be 20 billion light years away?
That's pretty amazing.
Why does gravitational lensing produce four copies of the star and not a whole circle of copies? I would have expected the light to bend evenly around the intermediate star, giving a halo-like effect.
I was also interested. It seems to be a combination of the intermediate galaxy being elliptical, and the star behind it being off-center from our point of view: https://physics.stackexchange.com/questions/14056/how-does-g...
WMAP measurements put the age of the universe at ~13.77 billion years, so I was initially perplexed by this part of the article: > The object acting as a lens turns out to be an elliptical galaxy located at a distance of approximately 7 billion light years (z = 0.556), while the source is at least 20 billion light years away (z = 3.03). ...but I found this explanation in the Wikipedia article on the most distant know…
WMAP measurements put the age of the universe at ~13.77 billion years, so I was initially perplexed by this part of the article: > The object acting as a lens turns out to be an elliptical galaxy located at a distance of approximately 7 billion light years (z = 0.556), while the source is at least 20 billion light years away (z = 3.03). ...but I found this explanation in the Wikipedia article on the most distant know…
Thank you, went to the comments to learn this. So the universe actually expands pretty fast then! Faster than the speed of light? Strangely...
WMAP measurements put the age of the universe at ~13.77 billion years, so I was initially perplexed by this part of the article: > The object acting as a lens turns out to be an elliptical galaxy located at a distance of approximately 7 billion light years (z = 0.556), while the source is at least 20 billion light years away (z = 3.03). ...but I found this explanation in the Wikipedia article on the most distant know…
Thank you, went to the comments to learn this. So the universe actually expands pretty fast then! Faster than the speed of light? Strangely...
WMAP measurements put the age of the universe at ~13.77 billion years, so I was initially perplexed by this part of the article: > The object acting as a lens turns out to be an elliptical galaxy located at a distance of approximately 7 billion light years (z = 0.556), while the source is at least 20 billion light years away (z = 3.03). ...but I found this explanation in the Wikipedia article on the most distant know…
Thank you, went to the comments to learn this. So the universe actually expands pretty fast then! Faster than the speed of light? Strangely...
The usual image is to consider ants traveling on an expanding balloon. The speed of light is the limit of how fast the ants can walk. The expansion of the universe is the expansion of the balloon. And now you see how two distant ants can be carried away from each other faster than they can walk towards each other.
If you understand manifolds and general relativity, this analogy is surprisingly exact.