100,236 reputation
4146257
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 7 months
seen 11 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.


May
6
comment Chasing a photon
Should 9.999999999c be 0.9999999999c? You can't travel faster than light. The equation used for the calculation is the relativistic addition formula.
May
6
answered Trying to understand explosions
May
6
answered Stopping an isolated metal ion
May
6
comment Do you feel more impact force when falling straight down or tipping over?
@LarryHarson: it's one of the classic problems you give students because their initial guess at the answer is always wrong :-)
May
6
comment Can a person at a photon sphere of a black hole decide where the black hole is?
@Anixx: intuition is a dangerous way to approach GR. Have a read through the relevant chapter of the Schutz book (that's the clearest analysis of the problem I've seen) then come back to us with any points arising from it.
May
6
comment Is it possible to achieve the speed of light within frames of references?
Hi LearnIT. I have linked a question that is basically the same as yours. As you near light speed velocities don't simply add together as they (approximately) do at lower speeds. So you can't exceed the speed of light by adding velocities as you've suggested.
May
6
answered Only one electron?
May
6
comment How close does light have to be, to orbit a perfect sphere the size and mass of Earth?
If you are a physics nerd (and why else would you be reading this :-) the reasons why your suggestion isn't the case are absolutely fascinating. It's because the radial coordinate $r$ that we use to measure distance from the centre and the time coordinate $t$ change as you approach the event horizon. Sadly you can't really appreciate what goes on without a lot of effort to learn the basics of GR, but believe me it's worth the effort!
May
6
comment How close does light have to be, to orbit a perfect sphere the size and mass of Earth?
@auxsvr: if the Earth was spherically symmetric (obviously it is only approximately so) the gravitational field outside it would be described by the same Schwarzschild metric that describes the exterior field of any sphere of the same mass. The tidal forces at the Moon would not be affected if a spherical Earth were to collapse to a black hole.
May
6
awarded  Good Answer
May
5
reviewed Leave Open What is the inertia caused by angular momentum when twisted on it's rotating axis?
May
5
reviewed Leave Open In what applications are lasers necessary vs. just convenient?
May
5
comment Can a person at a photon sphere of a black hole decide where the black hole is?
@Anixx: for an introductory book see chapter 11 in A first course in general relativity by Schutz or chapter 4 in Exploring Black Holes by Taylor and Wheeler. If you're feeling brave the general relativity bible discusses the orbits in section 2.5.
May
5
comment What exactly is an anti-neutrino?
@Yashbhatt: see Identification of particles and anti-particles. It is possible that neitrionos are Majorana particles though I get the impression this idea is going out of fashion.
May
5
comment Is there any significance of atomic orbitals?
See journals.aps.org/prl/abstract/10.1103/PhysRevLett.110.213001, we have actually measued the atomic orbitals of hydrogen. See also Anna's answer to Is there anyway to use a scientific instrument to measure the density of electron around the atomic orbital?.
May
5
answered Can a person at a photon sphere of a black hole decide where the black hole is?
May
5
awarded  Enlightened
May
5
reviewed Leave Open Is it possible to create artificial gravity by magnetizing iron in the blood stream?
May
5
awarded  Nice Answer
May
5
comment How close does light have to be, to orbit a perfect sphere the size and mass of Earth?
Yes, there are a few issues with that first paragraph, so I've rewritten it. @think123: no, you can't get light to orbit the Earth.