Recent content by kdlsw

If we know the mean number density of galaxies in the universe, the redshift z and the Hubble constant. Is it possible to find the mean distance between galaxies at such redshift? The redshift gives a ratio of two distances between the same pair of bodies, at two different time due to the...

The question is attached. I'm not sure how to approach to part (b). The energy released could be in 3 forms, the rest mass energy for those matter ejected during supernova explosion, the binding energy released as the atomic structure changed, the ejected matter carries off some kinetic...

The Hubble's Law v=H0D LHS of The Friedmann equation H2/H02 I am a bit confused with the following: 1: The Hubble constant H0 is the current universe velocity/distance ratio, it is basically a constant, so galaxies in the universe with a further distance, move away from each other at a...

It's the radiation emission, I am wondering how does rotation of the pulsar provides power to the non-touching nebula? by gravity?

Here is my understanding, please correct me if I am wrong, thanks At the end of the giant stage of a star, it experiences a supernova explosion, and turns into a neutron star (could be pulsar) or black hole, the explosion releases a lot of its matter. Here is what I don't understand: 1...

For part a I have (H0-ω\hbarm)|nlm>, which I think the (H0-ω\hbarm) part is the eigenvalue of the Hamiltonian, also is the energies? And mainly, I am not sure how to approach part b, the time variable is not in any of the states. I saw this in our lecture notes: ψ(r,t)=∑Cnψn(r) e-iEnt/\hbar...

It's part c I don't understand, why the expectation value equals to solid angle * sin3 i? I mean, what role does the solid angle play? Thank you

The problem is attached, and the official answer is given. The step in the answer does not make a lot of sense to me. How does the luminosity L converted directly into distance d, and why is the solar distance is used? And where does the dm=0.75 come from. It's just not making sense to me...

Here is my understanding, please correct me if I made any mistake Quantum physics theory suggests that information (the wave function, state, etc.) cannot be destroyed. All matters fall into a black hole will not be able to escape, which means all information of these particles stay inside...

My understand is, the virtual particle-antiparticle pairs created under uncertainty principle are not the same as the traditional particle-antiparticle (creates new particle after annihilation), the virtual ones does not produce anything, since they are created from nowhere, which the...

I have some basic confusion on the annihilation, please help me to understand these: 1 Does antiparticles all have negative energy? And the energy we talking about here is the rest mass energy? If it is, does it means antiparticles have negative mass since E=mc^2 ? My understanding on...

I have some confusion on the Bell-state measurement step of quantum teleportation, it's following: Let particle B and C be entangled, created by the EPR source, my understanding is, they are created with certain known superposition state, like this |ψBC>=√1/2 (|0A>|1B>+|1A>|0B>) which in...

Hawking radiation suggests that the anti-particles enter the black hole and annihilate with the normal matter in the black hole. Eventually the black hole will evaporate, which the information associates with those matter vanishes as well. This I believe is the information paradox. Here is...

Got it, Thanks!

Thanks a lot, but if I may ask a bit more, what is the meaning of having ∫ψn* ψm if they are just basis functions?