1,124 reputation
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bio website dotancohen.com
location
age 36
visits member for 2 years, 8 months
seen Apr 13 at 5:47

Apr
8
comment Precession period matching solar year
@Kvothe: Thank you, that is a wonderful video. I haven't seen the whole thing yet, but I will. However, interesting as it is, the video does not address the question of a stable 1:1 precession:year ratio.
Jan
15
comment Beads in 'perpetual motion'?
@GlenTheUdderboat: Nice, thanks!
Dec
25
comment Beads in 'perpetual motion'?
I'm going to have to work on my Japanese, that looks like just what I'm looking for! Welcome to physics.SE!
Dec
8
comment Does the strength of a smell depend on the volume or surface area of an agglomerate of material?
Thank you. Your first paragraph correlates strongly with my intuition, but your second paragraph addresses a very possible reason why the lower-surface-area dog shit stinks worse! And your third paragraph is now answered!
Sep
16
comment Lowest gravity on Earth's surface?
Relevant article
Sep
15
comment A machine which copies any object with 100% accuracy?
Which qualities? Macroscopic qualities such as functionality? Microscopic qualities such as surface defects? It goes back to my statement that the properties to be copied have to be well-defined.
Jul
19
comment Why aren't gas planets and stars fuzzy?
possible duplicate of Why is Jupiter so sharply defined?
Jul
9
comment Beads in 'perpetual motion'?
Wow, thanks, that is a great edit! It is so elegant once I see it! I assume that v is the initial velocity imparted by the hand? Thank you!
Jul
8
comment Beads in 'perpetual motion'?
Thank you. I suppose then that there is very little friction in this system? Also, I am having a difficult time determining a method for calculating the amount of force being exerted on the floor.
Jun
26
comment Why is the Pegasus launched from a subsonic airplane?
Thank you, I did not realise everything else in the launcher.
Jun
26
comment Why is the Pegasus launched from a subsonic airplane?
Thank you. I don't see any information even suggesting that the M-21 crash was due to to a supersonic separation.
Jun
26
comment Is space “real”, or is it some sort of accepted postulate?
Spacetime
Jun
26
comment Is space “real”, or is it some sort of accepted postulate?
I see, Peter, you mean the dimensions of space. You'll be happy to known that we can in fact measure them, and there there are more than just three of them!
Jun
6
comment Might a planet perform figure-8 orbits around two stars?
Thank you, the illustration makes it clear exactly why this system is unstable.
Apr
15
comment Other than the motion of the Earth, what else would cause parallax?
Right. Thank you!
Apr
15
comment Other than the motion of the Earth, what else would cause parallax?
I see, thanks. Therefore Bradley's discovery of aberration was the final bit of needed evidence?
Apr
15
comment Other than the motion of the Earth, what else would cause parallax?
Thank you for the very informative answer. You do discuss why aberration is easier to detect than parallax, which answers another (unasked) question of mine, but the core question is not addressed: Why was Bradley trying to measure parallax if it had not been discovered yet? And if it had been discovered (or suspected), yet the Earth was supposedly stationary (because Bradley's discovery proved that it wasn't), then what would explain the parallax?
Mar
22
comment How is celestial navigation done on a low-level?
Thank you. The Apollo podcast is very informative.
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.