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Questions related from Biswajoy Brahmachari
L= r x p is a 3 dimensional relation. In 4 dimensions r and p are 4 vectors and L is a 4x4 matrix. We want to discuss conservation laws related to angular momentum in 4 space time dimensions. Then...
12 September 2016 1,441 8 View
A detailed 3D map of galaxies will shed information on the abundance of dark matter and dark energy. Are there any surprises?
04 August 2016 8,804 1 View
Action at a distance is the simplest non-local interaction. But then in relativistic local field theories signals cannot travel at velocities more than the speed of light. This is taken into...
04 June 2015 2,308 14 View
Domain walls or boundaries are expected to form when a discrete symmetry is broken spontaneously. REF: Y. B. Zeldovich, I. Y. Kobzarev and L. B. Okun, Zh. Eksp. Teor. Fiz. 67 (1974) 3 [Sov. Phys....
19 February 2015 2,758 2 View
In Newtonian notion force between to masses m1 and m2 separated by a distance d is simply G m1 m2/d^2. This is an example of a theory which accepts action at a distance. A second example is...
17 June 2014 10,197 40 View
Nature of dark energy is unknown. It is a form of energy causing expansion of universe. Satellite based experiments such as Planck has estimated that 68.3 % of total matter and energy is in the...
10 June 2014 2,506 27 View
When delta T/T is plotted against angular separations between points we see several peaks in the plot. The first one is most prominent one is between l value 200-300, or in terms of angular scales...
17 May 2014 8,635 16 View
How, in Einstein's theory of gravity, can one replace the concept of force with that of the deformations of space time? Why is the orbit of mercury described better in terms of Einstein's theory...
18 April 2014 3,697 24 View
A 7 keV sterile neutrino is a good candidate for warm dark matter. What are the feynman diagrams by which a 7 keV sterile neutrino can be produced? What are the decay channels? By which diagram...
11 April 2014 5,945 3 View
Vacuum expectation value (VEV) of the Higgs scalar is responsible for fermion masses and also masses of the W+ W- and Z gauge bosons. Does it mean that the Higgs particle can extract energy out...
28 March 2014 2,274 10 View
If density perturbations are scale invariant then the dependence should be more like k^0, where k is the wave number. Then why do we define that scale invariant perturbations has spectral index 1....
15 February 2014 4,971 2 View
Proton lifetime is believed to be comparable to the lifetime of the universe. What is the most recent experimental numbers of proton lifetime ? What are the unified models which are ruled out by...
01 February 2014 5,067 3 View
Dark matter density should vary with radial distance to explain flat rotation curves seen in typical spiral galaxies like the milky way. What are the popular density profiles. How do they fit with...
16 January 2014 1,699 24 View
Experimental search for dark matter must rely on some model which tells us how our instruments, which are made of ordinary matter, interact with dark matter. Otherwise we cannot invent the right...
10 January 2014 2,907 11 View
Unless there is a symmetry reason to protect the Higgs mass near the electroweak scale, one loop effects will give large corrections. Is it super-symmetry or is it something else ? Or is it some...
02 January 2014 6,953 2 View
In a chirped pulse amplifier (CPA) one uses a short femtosecond laser pulse and then amplifies that to the pulse energy scales of terawatts and pentawatts. In doing so a stretcher and a...
01 January 1970 353 10 View
A discussion on relativistic effects, when electron move along a wire and carry currents. How much length contraction will it experience in it's own frame. And what is the relation between the...
01 January 1970 2,948 3 View
