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comment Seasons of Earths Orbit
Distance from the sun doesn't cause seasons. see physics.stackexchange.com/questions/26785/…
Jan
27
comment Safety of Polonium Isotope source
Or in a form which it couldn't be absorbed, such as plated on an insoluable stainless steel disk. If it stays on the disk you can swallow it and have it come out the other end!
Jan
27
comment How is sun's atmosphere (corona) hotter than the surface itself?
@barrycarter that doesn't explain how heat flows from 6000k surface to several million K corona
Jan
21
comment Why are four-legged chairs so common?
@Yakk only in a platonic ideal. Any microscopic difference in length or flatness means it will rock. That's why tripods have 3 legs
Jan
20
comment Why are four-legged chairs so common?
Only a 3 legged chair can be placed exactly on a flat surface. A 4 legged chair can only ever sit perfectly on an curved surface - and even then only in a single orientation
Jan
6
comment Is an x-ray maser possible?
@ChrisWhite - the dupe is a bit technical.
Dec
29
comment Beyond the gravity of a black hole
No - the fields are outside the blackhole, just closer than have been observed previously
Dec
8
comment Question about Gravitational Deflection of Light
Yes - it's even possible for light to orbit a blackhole and for you to see the back of your own head
Nov
26
comment How the speed of light is constant in the universe if it decreases in water and glass and some other objects?
When I explain SR I like to say that ε₀μ₀ are constant and that 'c' follows from them. Because "speed of light" is confused with being able to see the effect in most SR explanations
Nov
26
comment How the speed of light is constant in the universe if it decreases in water and glass and some other objects?
Even without the defn of the second, isn't it more normal to think of time changing in a gravitational field rather than permeability/permittivity changing ?
Nov
24
comment Is there any aspect of an explosion resulting from a nuclear weapon test that cannot be simulated using super computers?
@KyleKanos - yes but some pedant was going to come along and claim that there are effects which can't be modeled because of QM
Nov
23
comment Is there any aspect of an explosion resulting from a nuclear weapon test that cannot be simulated using super computers?
@dmckee yes, but it's also true that an experiment is only a measurement of that single system at one time - it doesn't mean it is a good measurement of the next one
Nov
19
comment Law of gravitation
@qftishard - you could watch the videos while standing near a very heavy object and see if they appear to be running fast
Nov
18
comment Weighing a baloon
It would show a more negative weight, ie more buoyant, ie less mass
Nov
18
comment Weighing a baloon
hint - think upside down
Nov
17
comment Electrons and photons at absolute zero?
Do photons feel the cold ?
Nov
16
comment Determine Height of Satellite Using Path Difference
The soln is to use the rate of change of difference between the receivers. I suggest starting where the sat is directly overhead and thinking what the distances look like some small fraction of a period later - draw some triangles
Nov
16
comment Determine Height of Satellite Using Path Difference
The speed is so much faster than the period you only have to consider the wave when you are overhead. 1 period later the satelite is 2.5km away
Nov
4
comment Do Magnets ever lose their magnetism, and if so how long does it take?
Iron magnets need a keeper to complete the circuit and preserve the magnetism.
Nov
1
comment What is the smallest item for which gravity has been recorded or observed?
The comet that ESA just landed a probe on ?