Ask A Physicist

Have a physics or astronomy question? Whether you're curious about tiny, elusive neutrinos or the most massive black holes in the universe, we can help.

We are graduate students, research scientists and faculty in the Department of Physics and Astronomy at University of Delaware. We are developers of quantum computers, space weather forecasters, planet hunters and more!

Please email your question to askaphysicist@physics.udel.edu. Scroll down for information on who can ask questions and how to phrase your question.

New Questions

The Space Race

• We're doing a project on JFK and the Space Race and we could use your expertise on that topic. Did you personally hear any interesting stories about the space race program? How directly involved was JFK with NASA?

Blue light and sleep deprivation

• I was recently advised to switch to red lights in the evening to help with my sleep patterns. I am told that the key is to achieve light as red as possible on the spectrum. Can this be achieved by filtering a white light through a red cover or does the light emitted have to be intrinsically red itself (eg the difference between a Christmas light with a red cover and a red heat night light for reptiles)?

Life and death in special relativity

• Two people are on a high speed, constant velocity train on opposite ends. One person is standing on the platform. The two people aim a laser beam at the center of the train at the same time in their reference frame. In the center of the train, there is a special gun that will shoot and kill whoever's laser beam reaches it first; but if the two beams reach it at the same time it will be disarmed. From the person on the platform's standpoint, one of them dies due to the relativity of simultaneity. From the two people on the train's standpoint, they both live. Later, the two people get off their high speed train and meet with the person on the platform. Is this not a paradox? The platform person clearly saw one of them die.

Extraterrestrial life

• What's the percentage of habitable planets in the Galaxy? What's the current estimate of how may planets have life?

Dangerous asteroids

• How do NASA scientists find dangerous asteroids? If they find one, what can we do about it?

Question Archive

• Light and Photography
• Particles
• Plasma
• Physical chemistry
• Solar System
• Extrasolar planets
• Brown dwarfs
• Gravity
• Black holes
• Cosmology
• Neutrinos
• Special relativity
• General relativity
• K-12 Education

Who can ask questions?

• We welcome questions from K-12 students and teachers. We ask that students put their age or grade level in the email so we can answer at the appropriate level.

• Non-scientist members of the general public are also encouraged to submit questions. To help us answer at the right level, it's helpful if you add a little bit about your background -- for example, "I'm an accomplished amateur astronomer" or "I'm usually not interested in science, but I read something about climate change and I want to find out if it's true."

• College students may submit questions as long as they are not homework questions (see below). We can help with general physics concepts, but we will not compute or calculate anything for you.

• We advise journalists working on deadlines to contact individual scientists directly, rather than send questions to Ask A Physicist. The contributors to this page are volunteers, and we cannot guarantee that questions will be answered immediately.

• Professional physicists or astronomers should not use this service. We do not review manuscripts or check calculations.

How should I phrase my question?

• Make it specific enough that we can answer it in 1-2 paragraphs: "What types of nuclear reactions can produce neutrinos?" rather than "Tell me everything you know about neutrinos."

• However, if you make it too specific, you will trigger our homework question alert. Questions such as "Describe the five ways to measure the temperature of a star" or "If I throw a ball upward at 2 meters per second from a height of 1.5 meters, how high will it go?" will not be answered.

• We might not be able to help with questions that are specific to your locale, such as "What was that flash I saw in the sky at 10:00 PM last night?"