Debajyoti Sarkar

7 Questions 11 Answers 0 Followers

Questions related from Debajyoti Sarkar

Is it possible for the Hamiltonian to be non-hermitian?

We consider the Hamiltonian to be Hermitian to make energy eigenvalue real. But, say for some infinitesimal region we can't measure the energy. Can the Hamiltonian be non-hermitian in that case?

02 April 2015 8,650 10 View

Can someone suggest what would be the corresponding Hamiltonian with a time evolution operator U(t2-t1)= σ(z)?

Let's consider, I have an equation U(t2-t1) χ= σzχ. Here U represents the time evolution operator and χ is the spin state. Now if take log of both side, left side gives the Hamiltonian while the...

02 April 2015 751 2 View

How much does the Lithium problem affect our understanding of the Big bang theory?

The observed Lithium abundance is in disagreement with the standard big bang model. What are the possible solutions to the problem? How much the observations are reliable in this case? Is it...

30 March 2015 8,571 11 View

How to calculate power spectrum from density perturbation?

What is the method for finding the power spectrum from the distribution of density? Considering I have the distribution of density over a certain volume.

02 May 2014 3,977 2 View

Is there any experimental evidence for how much time a photon takes to flow from the core to the surface of the sun?

I have seen different estimations of photon diffusion time in different papers (30000 to a million years). There are many different mean free paths used. I want to know if these results are just...

02 May 2014 3,790 8 View

How should I choose a particular gauge in first order perturbation in general relativity?

In the case of general relativity the change in coordinate can give rise to fictitious perturbations, for which we can use gauge invariant variables or we can also choose a specific gauge. My...

16 April 2014 3,577 3 View

Is not the second law of thermodynamics violated in cyclic cosmology?

It was shown by Tolmann that if the cosmological constant is zero then no minimum radius of universe exists (rate of expansion becomes negative infinite at R=0). Now dark energy gives a...

09 August 2013 7,906 6 View