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visits member for 2 years, 10 months
seen Dec 12 '11 at 0:52

Nov
1
comment why evaluate at lambda = 0
hmm... yeah i guess this is just a mathematical thing you can't really draw a picture
Nov
1
comment why evaluate at lambda = 0
this is analgous to choosing a vector with a tail at the origin in 3-d euclidean space? thx
Nov
1
comment why evaluate at lambda = 0
thanks david... i'm wondering why the interval is [0.1]? but this is helpful
Oct
30
comment why is time order invariant in timelike interval?
i don't understand this diagram at all...
Oct
30
comment why is time order invariant in timelike interval?
perhaps I do not understand what is meant by "rotating a point". is the problem. about what axis?
Oct
30
comment why is time order invariant in timelike interval?
ron i'm a little confused... I understand the concept of a circle and I believe that indeed that is the equation for a hyperbola... what I do not understand is what you mean by "rotate a point continuously cannot move points from the upper hyperbola to the lower hyperbola" . to rotate a point on the circle you just spin it... how can you rotate a point on a hyperbola?
Oct
30
comment why is time order invariant in timelike interval?
in this sense time-order is associated with the plus or minus sign of t. interesting thanks, david... ron's answer is a little over my head... I need to look at that some more...
Oct
30
comment why is time order invariant in timelike interval?
this one is helping somewhat ... physics.stackexchange.com/questions/12435/…
Oct
28
comment Inverted Harmonic oscillator
as an aside question, can we think of this in terms of Forces. normally a harmonic oscillator drives the particle back to where it was, whereas this force would drive the particle away from where it is faster and faster... seems like the energy would diverge very quickly, but still are there not quantized solutions?? -- oops i see lubos has given those explicitly is there any further information on this subject of interest?
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
heh ok... you right
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
yo ron... what if you cut out some of the fabric from the glove and then repatch it? what is the mathematical term for that?
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
yo ron... can you point me to a discussion of how 3-d objects ( or higher dimensional objects behave under inversion etc)?
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
yo ron thx for the tip! as a further point I see also you cannot turn a left-handed glove into a right handed glove by a translation and a rotation.
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
first we know the improper rotation changes the handedness of the coordinate system. now, imagine a rigid body rotating about the origin. say there are initially some right handed set of coordinates fixed in the rigid body frame at t=0, and then we start rotating the rigid body about the origin of this coordinate system. There is simply not way you can rotate such that the handedness will change!! the rotation of a rigid body is completely defined by the euler angles and if you imagine any of these 3 rotations, there is no way to actually invert invert the axis by such a rotation.
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
an inversion is like a plane-reflection of a rigid body... without a rotation ( thus the handedness get's changed right?)
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
that has to do with certain molecules doing wierd quantum things ( NH3 does this supposedly) but I don't want to get into all that. supposedly NH3 can tunnel into it's left-handed state or something (i don't understand it classically so I'm not too sure)
Oct
24
comment understanding why inversion cannot be accomplished by a rigid change
if you look at the vector r = (1,0,0) maybe there is a way to explaon this with a simple example like that, i'm workin' on it right now...
Oct
23
comment should I take notes in class
this question is asking about note-taking for physicists, this is not a question about general note-taking in that sense it is on topic... I'm asking about physicists and their note taking practices ...
Oct
23
comment should I take notes in class
i see threads like "what does it take to be a top physicist?" and "how to study mathematics as a physicist?" i'm not sure how you can justify closing this and leaving those open ?? please add a a comment
Oct
23
comment should I take notes in class
how do i get reputation of 20?