94,455 reputation
3127233
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 6 months
seen 6 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.


15m
reviewed Approve suggested edit on With what velocity should an alpha particle travel towards a Cu nucleus so as to arrive at a distance of 10^-13 meters
15m
reviewed Approve suggested edit on Expanding a ket in the position basis?
16m
comment With what velocity should an alpha particle travel towards a Cu nucleus so as to arrive at a distance of 10^-13 meters
Calculate the potential energy change in moving from infinity to $10^{-13}$m. The initial kinetic energy has to be equal to this potential energy change.
18m
comment Thoughts on the ice cube from orbit problem
@Whelp: what enthalpy is that? Enthalpy of formation? If so that's the energy compared with 0.111kg hydrogen and 0.888kg oxygen.
1h
revised Can an elliptical orbit take the same time as a circular obit?
Add note on film
1h
answered Can an elliptical orbit take the same time as a circular obit?
2h
revised Bug riding on a ball moving at almost the speed of light
Add image
2h
answered Bug riding on a ball moving at almost the speed of light
3h
comment Bug riding on a ball moving at almost the speed of light
Are you asking about the height of the thrower in the reference frame of the bug, or are you asking what the bug sees i.e. if the bug took a photo what would appear on the photo? These aren't the same because the latter includes the travel time of the light.
3h
reviewed Approve suggested edit on Bug riding on a ball moving at almost the speed of light
3h
reviewed Reviewed Why wasn't the moon visible during the day a few decades ago?
4h
answered Why are Silicon-Silicon bonds weak?
5h
reviewed Leave Closed Solution of the time independent Schrödinger wave equation using Green function
5h
reviewed Delete Why is the pressure inside a soap bubble higher than outside?
5h
reviewed Close How do heated showers/faucets work?
7h
awarded  speed-of-light
15h
reviewed Close what is the physical significance of pearson correlation coefficient?
15h
comment Cosmic Expansion - Why aren't we ripped off yet?
The universe hasn't been expanding exponentially since the Big Bang. For the first half of its life it was expanding as roughly $t^{2/3}$, and the exponential contribution to the expansion only became significant around 6 billion years ago. However the future expansion will tend towards exponential as the density of matter dilutes towards zero.
15h
comment Thoughts on the ice cube from orbit problem
@parceval: my calculation is based on the fact you need to bring the ice to a stop (unless you want it smash your glass). All the energy needs to be dissipated to slow the ice from its 20,000 or so mph orbital velocity to zero. However the ice meteor won't be coming to a stop - it'll be hitting us at something like 20,000 mph. This wouldn't be pleasant.
17h
reviewed Leave Closed velocity of light