1,240 reputation
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bio website dotancohen.com
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age 37
visits member for 3 years, 3 months
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Dec
26
asked Other than the motion of the Earth, what else would cause parallax?
Dec
17
awarded  Nice Question
Dec
12
comment Blue-shifting as opposed to violet-shifting
Thanks, Alan, this is a terrific answer. It doesn't address the question (relativistic blue-shifting), so I won't mark it as accepted, but it is extremely well-written and well-researched. This was fun to read! Thank you!
Dec
11
comment Blue-shifting as opposed to violet-shifting
Nice, thanks! This addresses the red herring, not the question, but it is a very concise way to address the colours of the sky. I wonder why we don't see the sky green, though, as green is no less dominant on the graph and our eyes are very sensitive to green.
Dec
11
comment Blue-shifting as opposed to violet-shifting
@Kitchi: So I guess an ultraviolet source would be shifted away from the blue, yet be erroneously called blueshifted.
Dec
11
asked Blue-shifting as opposed to violet-shifting
Nov
28
comment How distorted does the Andromeda Galaxy appear to us due to the speed of light?
Thanks, Martin.
Nov
28
accepted How distorted does the Andromeda Galaxy appear to us due to the speed of light?
Nov
27
asked How distorted does the Andromeda Galaxy appear to us due to the speed of light?
Oct
24
accepted Maximum resolution per lens size
Oct
24
comment Maximum resolution per lens size
Thanks John! I did realize that a larger lens lets in more light, but I was unaware of spherical aberration.
Oct
24
comment Maximum resolution per lens size
I see, thanks. You've given me the keywords that I do need to continue research. I want to see how far they are pushing this poor lens. However, how is quality reduced as lens size is reduced? All the professional camera have large lenses, surely there is some advantage to a larger lens.
Oct
24
asked Maximum resolution per lens size
Oct
12
comment Lowest gravity on Earth's surface?
Thank you Dimuthu!
Oct
12
accepted Lowest gravity on Earth's surface?
Oct
12
accepted Gas pressure equalisation: Where does the excess energy go?
Oct
2
comment Will a hole cut into a metal disk expand or shrink when the disc is heated?
This is analogous to the reason that the holes in cookies get smaller, not larger, when baked.
Oct
2
answered Does Earth's rotation change at a constant rate?
Oct
2
comment Gas pressure equalisation: Where does the excess energy go?
Thanks John. The microscopic explanation of the gas molecules' speed was quite what I was missing. If Zephyr doesn't write back as an answer then I'll accept this one.
Oct
1
asked Gas pressure equalisation: Where does the excess energy go?