108,868 reputation
4165295
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 9 months
seen 28 mins ago

Semi retired old time computer nerd who started programming on a Commodore Pet.

Since I'm also active in the Physics forum I should add that I started as a theoretical chemist, moved into solid state photochemistry and finally worked in industry as a colloid scientist. I only became a full time computer nerd in 1997.


Oct
19
comment Loop quantum gravity- is the critical density sufficient to form a 'black hole'?
The universe is not described by the Schwarzschild metric so it has no Schwarzschild radius.
Oct
18
comment While finding escape velocity, does human mass counts as the mass of Earth?
@FranciscoPresencia: the mass change due to absorption or emission of radiation is negligible.
Oct
18
reviewed Looks OK Why the current decreases with increase in voltage in transmission lines? But according to Ohm's law current should increase with Voltage
Oct
18
reviewed Leave Open Self-replication of gravitons in string theory
Oct
18
reviewed Leave Open Doesn't the second postulate of special relativity imply the existence of “luminiferous ether”?
Oct
18
awarded  Good Answer
Oct
18
comment Building blocks of particles in different theories
No. The concept is specific to quantum fields. The motion of planets is described by a classical field and this is completely different.
Oct
18
comment Building blocks of particles in different theories
You'll have to clarify what excitation at the macro-scale means.
Oct
18
comment Building blocks of particles in different theories
The idea of a particle as an infinitesimally small dot is not a good description. Particles are described as excitations in a quantum field. They are point like in the sense that by going to arbitrarily high energies the particle can be resolved with arbitrarily great precision, but this does not mean quantum field theory models them as points.
Oct
18
comment Self-replication of gravitons in string theory
The phrase self-replication was used by the IO9.com journalist not by Luboš. It is not a term used by physicists.
Oct
18
comment Self-replication of gravitons in string theory
I don't think the phrase self-replication has any special meaning in physics. Are you asking how string theory removes the divergences when summing the Feynmann diagrams for gravitons?
Oct
18
reviewed Reject suggested edit on Is the universe finite or infinite?
Oct
18
comment How does EM radition depend on the reference frame?
If you take off in a rocket you know you're accelerating because you can feel the g forces. However if you leap out of the ISS and fall to Earth then you will feel no acceleration even though as viewed from Earth you are accelerating. So we have two cases where you are accelerating but they are fundamentally different. The question is whether an electron accelerates when falling an a gravitational field and I'm not sure anyone knows the answer.
Oct
18
comment How does EM radition depend on the reference frame?
The spacecraft can do what it likes. If the charge isn't accelerating it won't radiate. In special relativity acceleration is absolute so there is no ambiguity about whether the spaceship or the charge is doing the accelerating. In general relativity the question is rather harder.
Oct
18
awarded  Nice Answer
Oct
18
comment How does EM radition depend on the reference frame?
Only accelerating charges radiate. Charges moving at constant velocity do not radiate.
Oct
18
comment Which wavelength of light can reflect easiest on any material?
See Why glass is transparent?. Although this is specifically about glass it applies to any material.
Oct
18
comment While finding escape velocity, does human mass counts as the mass of Earth?
We've both assumed that the average human is well fed :-)
Oct
18
answered While finding escape velocity, does human mass counts as the mass of Earth?
Oct
18
comment Can anyone tell me what's this equation?
See this article on Sean Carroll's blog