Recent content by Epistimonas

Okay so is what you're saying that the definition of a vector is that it is invariant under translation and rotation, and that in Euclidean space, vectors are not invariant under rotation and that in Minkowski space they are?

Okay so there must be a mathematical way of showing that for a (+,+,+,+) signature the speed of light is not the same in every reference frame, and that for a (-,+,+,+) or it's equivalent the speed of light has a constant speed in every frame? And if that can be shown, then it could then be...

Right okay that is a grand answer to my question, thank you. I am familiar with the Poincare group that contains the isometries of Minkowski spacetime. Essentially the answer you gave me was, "The negative time unit vector is required to fulfill the requirements of the 10-dimensional Poincare...

Why is the unit vector for time in Minkowski space i.e. the fourth dimension unit vector always opposite in sign to the three other unit vectors? The standard signature for Minkowski spacetime is either (-,+,+,+) or (+,-,-,-). Is there some particular reason or advantage for making time...

According to Wikipedia: In quantum mechanics, a phase factor is a complex coefficient eiθ that multiplies a ket or bra . It does not, in itself, have any physical meaning, since the introduction of a phase factor does not change the expectation values of a Hermitian operator. [1] ^...

By the way, I got it, thanks!

Ahh ok, I think I understand. So basically I just solve the Friedmann equations for H with z = 6, 0.27 for the matter density, and 0.73 for the energy density? I'm about to try it I'll let you know how it goes.

How can you mathematically calculate the Hubble constant at different redshifts? I know it's possible, and I can get the number by using the Cosmos Calculator: http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html But I want to know the equation they used to calculate the Hubble Constant...

I have these thoughts sometimes too, that I might not exist and that everything going on around me and my relationships and human interactions are all just part of some "computer simulation" or "imaginary universe" and that none of it really matters. Those thoughts begin to drag me into a bout...