312 reputation
39
bio website web.me.com/charlesegrant/…
location Seattle, WA
age 58
visits member for 3 years, 6 months
seen 1 hour ago

Jul
21
awarded  Enthusiast
May
5
awarded  Notable Question
Dec
11
answered How to determine what an object is composed of?
Jul
15
awarded  Commentator
Jul
15
comment Why do they consider radioactive matter with long half lives more dangerous than matter with a short half life?
-1 You can't simply say that long lived radioisotopes won't cause biological problems because the absolute activity depends on the amount present as well as the half-life. You also are ignoring factors like decay mode. For example Iodine 141 is a beta emitter while plutonium is an alpha emitter. Alpha particles cause far more biological damage.
Mar
15
comment Why does the speed of light $c$ have the value it does?
Actually, several theorists (Dirac among others) have suggested that the fundamental constants change with time. See for example physicsworld.com/cws/article/news/2010/sep/02/…
Mar
15
answered Why does the speed of light $c$ have the value it does?
Mar
13
comment Do Nuclear Power Plants have shutdown and cooling systems protected from a nuclear generated EMP?
While I agree that the public perception of the risks of nuclear power are exaggerated it doesn't help to dismiss the actual risks. The failures at Three Mile Island and Fukushima resulted in billions of dollars of damage to the infrastructure of those plants and in the case of Fukushima did result in significant radioactive contamination of the surrounding area. That's a far cry from 'the worst thing you can expect is failure to provide power'.
Feb
27
awarded  Yearling
Oct
27
awarded  Popular Question
Sep
2
awarded  Teacher
Sep
2
comment How do we know that C14 decay is exponential and not linear?
Because the half-life of C-14 is long compared to a human life time it takes careful, sophisticated measurements to demonstrate the exponential decay. However, it's probably worth noting that there are many other radioactive isotopes with very short half-lives. It a standard exercise in 1-year college physics labs to measure the exponential decay of radioactive isotopes of Silver. See for example carleton.edu/departments/PHAS/P128/lab/AgDecay04.pdf
Sep
2
answered How does a half-life work?
Mar
1
revised Starting a physics Ph.D. at 60?
added 275 characters in body
Mar
1
comment Starting a physics Ph.D. at 60?
thanks for the answer. I work at a university so I have online access to most of the journals. Not being current in the field, I tend to rely on the editorial and peer review process in the journals to pick stuff out, rather than going to ArXiv and browsing. Is that "so last century"?
Mar
1
comment Starting a physics Ph.D. at 60?
thanks for the answer. As you may have seen from my profile I'm a fellow Seattleite. I've certainly been thinking about the evening Master's program at the UW. They make it pretty explicit that it is not a gateway to the Ph.D. program, though they also note that a few folks have made the transition. Did you apply to the UW Ph.D. program?
Mar
1
comment Starting a physics Ph.D. at 60?
@nibot, re willingness to relocate. Yep, this is a strong constraint. I live in the NW corner of the US and would by far prefer to stay here. I work at the University of Washington and the Physics program here is fairly well regarded, and therefore competitive. I've never seen them offer a staff programming job. The nearby "Applied Physics Laboratory" periodically has openings for programming staff, but they only work in marine remote sensing. Actually my wife and I would love to live in the UK for a few years, but there I think we're entering the realm of pure fantasy.
Mar
1
awarded  Scholar
Mar
1
accepted Starting a physics Ph.D. at 60?
Mar
1
comment Starting a physics Ph.D. at 60?
@nibot, I think your comment "open a dialog with some faculty in potential departments and see what they say." is clearly the "correct" answer. Though I confess I was mostly looking for anecdotes.