77,756 reputation
178167
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 3 months
seen 4 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.


18m
reviewed No Action Needed If you shoot a light beam behind the event horizon of a black hole, what happens to the light?
18m
reviewed Leave Open Will it start rolling?
1h
comment Why are people weightless whilst in orbit around the earth? ISS? Sattelites?
possible duplicate of Weightlessness for astronauts
1h
answered Tokamaks and the reason they are not efficient
1h
comment How many years would it take to travel 490 light-years?
I'm not sure this is really homework, or even homework-like. I can't find a question/answer on the site that does the calculation for steady acceleration. While the calculation is simple for us nerds I would have guessed it's hard for all but undergrads and above. Maybe we need a reference question/answer that we can link to for similar future questions.
1h
comment How many years would it take to travel 490 light-years?
The elapsed time for the occupants of the spaceship can be less than 490 years.
1h
comment Could compression of electromagnetic waves cause red shift
Can you expand on supernovae judged to be closer to us, based on luminescence, appear to be moving away from us faster than distant supernovae judging by red shift. Maybe provide a reference?
1h
answered Could compression of electromagnetic waves cause red shift
13h
comment Why do we orbit around the sun instead of one the other stars?
How do you know an alien student sitting in a classroom orbiting another star isn't asking itself exactly the same question?
13h
revised Is it probable that planets will stop orbiting in ellipses?
Correct typo
14h
reviewed Approve suggested edit on Does centrifugal force exist?
14h
reviewed No Action Needed In interferometry, what is the origin of the name “Airy function”?
14h
comment Can we physically “time travel” to the future?
@Bombyxmori: so are you proposing a discontinuous world line? If so, your question is science fiction not physics. If not then the time travel is simply the special relativity sense that you have already ruled out (and which, incidentally, does not violate any conservation laws).
15h
awarded  Nice Answer
15h
comment Can we physically “time travel” to the future?
Note that the various (physically motivated) proposals for time travel into the past do not rely upon discontinuities in the world line. The world line is continuous but can form a closed loop.
15h
comment Can we physically “time travel” to the future?
I assume that by time travel you mean some object would disappear and reappear in the future i.e. its world line would be discontinuous. Since there is no physical mechanism to explain how this might happen it's impossible to comment on whether it does or doesn't respect conservation laws.
15h
comment Does the induced charge on a conductor stay at the surface?
The electrons in a conductor are free to move. Therefore if there is any potential gradient in a conductor the electrons will move along it. At equilibrium there cannot be any potential gradient (i.e. electric field) inside the conductor or the electrons would move and it wouldn't be in equilibrium.
15h
comment Could an orbiting mass generate power?
@Devrim: that applies only when the orbiting body is in a geostationary orbit (or higher I suppose). At lower altitudes the cable isn't moving fast enough to keep it in orbit.
18h
reviewed Close How to pump water from a canal without using an electrical machine?
18h
reviewed Close A relation between the law of multiplication with average velocity and time