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12351
bio website science20.com/…
location Bangalore, India
age
visits member for 3 years, 11 months
seen 11 hours ago

Theoretical physicist by training, PhD in spin-polarized quantum systems. Inventor of the DPD micro-hydrodynamics simulation methodology, and specialized in computational physics. Currently chief scientist for a large multinational company. Blogger at Science2.0.


Dec
15
comment Is it possible to assign a physical radius to a black hole?
It is always possible to assign a circumference to a black hole. One can therefore conveniently define a black hole radius as $1/2\pi$ times its circumference.
Dec
14
revised How to calculate the value of gravitational acceleration of my town
added 9 characters in body
Dec
14
revised How to calculate the value of gravitational acceleration of my town
Explained latitude
Dec
14
revised How to calculate the value of gravitational acceleration of my town
added 284 characters in body
Dec
14
answered How to calculate the value of gravitational acceleration of my town
Dec
14
comment Is a block of cotton heavier than a block of iron?
Would be better to re-word this question into something like "a block of cotton and a block of iron keep a two-pan weighing scale in balance. Which block has larger mass?"
Dec
13
awarded  Excavator
Dec
13
revised How does the formation of a solar system not break the second law of thermodynamics?
Title (made more specific)
Dec
12
revised Collisions in special relativity
added 17 characters in body
Dec
12
answered Collisions in special relativity
Dec
8
comment Why do universal constants have the values they do?
Duff's more recent take on "How Fundamental Are Fundamental Constants?": arxiv.org/abs/1412.2040
Dec
8
comment Measuring the speed of light and defining the metre - absolute or relative?
Maybe the down-voters care to elaborate? The above should be undisputed and is absolutely mainstream physics. Strangely enough, some consider the above simple insight ("dimensionfull constants are not fundamental") worthy of publication: arxiv.org/abs/1412.2040
Dec
7
revised From escape velocity to gravitational acceleration
added 5 characters in body
Dec
7
comment From escape velocity to gravitational acceleration
@Joe - small correction: take the square of the escape velocity and divide by twice the radius to get $g$.
Dec
7
revised From escape velocity to gravitational acceleration
Title
Dec
7
answered From escape velocity to gravitational acceleration
Dec
6
comment Why quantum computer is so fast factoring numbers?
Would be nice if physics.stackexchange.com/users/399/peter-shor answered this one...
Nov
25
awarded  special-relativity
Nov
19
comment Dumbed-down explanation how scientists know the number of atoms in the universe?
@ArturoDonJuan - I didn't forget, I ignored it. The above is an order of magnitude estimate, relatively tiny contributions to the number of atoms in the universe are better ignored as these constitute no more than a distraction.
Nov
14
comment How is the scattering length in 2d defined?
This approach when applied to elastic scattering in 2D leads to logarithmic divergences. This is related to the fact that the elastic phase shifts to lowest order are logarithmically dependent on the wave number.