the physicist

Ask the Physicist!

Do you have a question related to physics? Since 1999 I have answered more than 4000 questions on line and many more by brief email. To see how I select questions to answer, link here. If you do not submit a valid email address, I will not answer your question; if you do not receive an immediate automatic reply to your question, your email address was not valid or your mail server rejected the message. Please read the groundrules for the site. If the answer is to your liking, please consider making a donation to help support this service. A history of past questions and answers may be seen by clicking here. I have organized old answers into categories for easier searching or perusing.

There is now an Ask the Physicist facebook page. I cannot answer questions there because the formatting is too limited, but I will use the page to note recent answers which I find particularly interesting. If you "like" the page you will receive such notifications. Also, if you would like to make comments on my answers, that would be a good place.


  1. Questions which

    1. violate groundrules, (I do not do homework. Please stop sending me obvious textbook problems. Likewise, this is not a tutoring site; do not ask me to help you with your homework. Note, though, that many sites which advertise on this site provide homework help or tutoring.)

    2. I consider to be "off the wall",

    3. are not likely to be of general interest to the many people I know read the answers, or

    4. do not include a valid email address (if you don't get an immediate "we'll be in touch" reply, your email doesn't work),

will simply be discarded. In the past, I have tried to answer all questions even if the answer is simply that I won't or can't answer, but that is becoming too time consuming. If you don't get an answer within a week or two, you can always ask again with a "plea"; no guarantees, though.

  1. If your question is clearly astronomy or astrophysics, particularly detailed questions about black holes, stellar evolution, dark matter or dark energy, the big bang, etc., areas in which I am not expert, I may not answer. If you google ask astronomer or ask astrophysicist you will get lots of possibilities. I recommend NASA's Ask an Astrophysicist. Another good place is Curious about Astronomy?

  2. Finally, I am not a psychic! Look them up, psychic and physicist!


Please read site groundrules and peruse the FAQ page before submitting your question. You can also search the site for previous answers. Although I do not answer homework questions or do tutoring, many of the sites which advertise on this site (look left) do.

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