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Jun
14
comment Stronger than Newton's laws?
I agree with the sentiment of @Rasko's comment. However, I don't think it's appropriate to refer to running masses and couplings as "t'Hooft's law". Perhaps I'm being pedandic, but that's how I feel.
Jun
13
comment Can a planet cover the whole sky as seen from its satellite
@Philip: No, the effect of an atmosphere with increasing density at lower altitutes would increase the extent of the sky covered by the large planet. (Before I wrote it above I too had to take a minute to consider in which direction the light would refract.) Imagine you're standing on the satellite looking at light from the very edge of the planet; almost parallel to the surface of the satellite. As it enters a medium of higher refractive index, at an oblique angle, it will bend towards the normal-to-the-surface. I.e. into the surface of the satellite, thus preventing you from seeing it.
Jun
13
comment Do color-neutral gluons exist?
@Lubosh: Your statement "This is more manifest if..." reminds me a little of when physics text books often say things like 'this easy proof is left to the reader' when in fact the proof would only be easy if the reader happened to be a professional in that particular subject. I've been meaning to ask about the physical significance of diagonal and off-diagonal matrix entries for some time. My reason for not doing so is that I feel it would be a bit too mathsy for physics.SE and visa versa. I would therefore be hugely greatful if you could elaborate on your second paragraph a little.
Jun
12
comment Will the night sky eventually be bright?
@Zasso: It seems @Ted B has explained things better than I could have hoped to have worded it myself. As far as I'm concerned, his answer nulifies our very minor dispute. Bygones?
Jun
12
comment Can a planet cover the whole sky as seen from its satellite
@M.Sameer: Good point. I don't know, guess we'll have to wait for a planetary physicist to pitch in. I was merely pointing out that the refractive properties of an atmosphere would be an exception to both the "no" answers so far. The whole situation was pretty hypothetical from the start..
Jun
12
comment What does it mean that the neutral pion is a mixture of quarks?
Welcome to our wierd-yet-wonderful quantum-mechanical Universe! Joking aside, I'm sure someone will be able to offer you a more expansive answer before long.
Jun
12
comment Can a planet cover the whole sky as seen from its satellite
@Philip: What if the satellite had a thick atmosphere, causing the light from planet to be refracted?
Jun
12
comment Will the night sky eventually be bright?
@Zasso: Unless I'm just getting confused by your wording, you seem to have contradicted youself. I.e. "light beyond a certain point just can't make it due to being outrun by the acceleration" - exactly what I was getting at. But, you also said "over time, [sic] the number of observable objects will increase drastically, and quite possibly infinitely" - to me, this contradicts your comment above. Also, according to current models at least, it's incorrect.
Jun
12
comment Will the night sky eventually be bright?
@Zasso: I'm afraid you're wrong. Due to accelerating expansion the cosmological horizon will get smaller, not larger. Light from the most distant stars will be increasingly red-shifted. Eventually their light will not reach us at all as the space between us and them will be expanding faster than light can travel. This does not violate special relativity since no information is being transfered whilst the space expands. In the remote future the Universe will be a very dark, cold place. That shouldn't stop us enjoying it for now though :-)
Jun
9
comment Why do we say that the earth moves around the sun?
@Random: You're right of course (+1). I mentioned it purely due to its explanation of how either of two reference frames moving relative to eachother may be considered to be 'at rest'.
Jun
9
comment Formulas for ball rolling in a bowl?
@Dane: Your welcome. Glad I could help :-)
Jun
9
comment Why do we say that the earth moves around the sun?
@Marek: Complexity of the equations isn't really the issue here. I was merely contending the use of the phrase "more true". In that I thought 'more convenient', 'more sensible' or 'a more natural choice' would be a more physically correct statement.
Jun
9
comment Why do we say that the earth moves around the sun?
Welcome to SE.com but I'm afraid your answer contains a few errors. Grammar: "churches" implies the buildings whereas 'the Church' implies the organisation. Spelling: "though-t" ends with a 't'. Physics: the Sun rises in the East and sets in the West, thus it does move around the Earth (Galilaen relativity[1] is sufficient for this and has been understood since the 17th century,) and the Earth and Sun orbit around the barycenter[2] of the solar system. [1]: en.wikipedia.org/wiki/Galilean_invariance [2]: en.wikipedia.org/wiki/…
Jun
9
comment Why do we say that the earth moves around the sun?
@Mark: Great video-link. :: chuckles ::
Jun
9
comment Why do we say that the earth moves around the sun?
@Lubosh: "In this sense, the heliocentric frame is more true." I don't agree with the phrasing of this statement - it is more convenient perhaps, but it is equally as 'true' as any other choice of reference frame. If the geocentric equations of motion correctly predict the motion of all celestial bodies then surely they too are 'true,' albeit a little more complicated.
Jun
8
comment Given a radius and velocity calculate position of an aircraft banking to make a turn in three dimensional space
In keeping with the comment by @Vintage, it would be helpful if you could explain why you have asked the question - I.e. the circumstances that let you to it and what you want an answer to achieve. As it stands it quite difficult to interpret and therefore answer.
Jun
6
comment What does cross-track wind mean?
@Georg: "You can English good enough.." Lol.
Jun
6
comment Formulas for ball rolling in a bowl?
Knowing a bit more about your background will help people to pitch answers at the right level. Are you familiar / comfortable with vector calculus? In what language are you attempting to program it in? How experienced with that language are you?
Jun
4
comment Can heat be transfered via magnetic field in a vacuum?
In light of the discussion ensuing from your answer I'll give you a (IMO) deserved +1. I'd like to see that calculation though.
May
27
comment Is it outside science to figure out the precise string compactification of our universe?
@Mitchell: The two comments you made in conversation with Peter Woit more than constitute an answer to the OP's question, and a good one at that. Transfer them over and I'll certainly give it +1 ;)