Relativity/Questions
| Subject | Date Asked | Expert |
| relativity/quantum mechanics | 1/28/2012 | Uncle Ben |
| Q: Are infinitely small and infinitely large the same and is our concept of size out of proportion to ... A: The space in between atoms is just there. It does not collapse, because there are forces that ... | ||
| relativity/quantum mechanics | 1/28/2012 | Uncle Ben |
| Q: Are infinitely small and infinitely large the same and is our concept of size out of proportion to ... A: The size of an object is determined by the combination of the forces that keep atoms separated but ... | ||
| Special Relativity | 1/25/2012 | Uncle Ben |
| Q: First, I would like to thank you for answering my previous question in a very clear way. So, I ... A: Of course, Samir. If an object of (rest) mass m is subject to a constant force, you are correct in ... | ||
| General Relativity | 1/20/2012 | Uncle Ben |
| Q: Usually, when I read about general relativity, I found remark that the theory explained what causes ... A: Seamier, you have raised a deep question. Every explanation shifts the question. No matter what ... | ||
| Twins | 1/12/2012 | Uncle Ben |
| Q: If there are two twins, one lives at the North Pole and one lives at the Equator, will there be an ... A: Yes, Elena. Compared to the brother at the north pole, the other will be older. There are two ... | ||
| Length perpendicular to the direction of motion | 1/7/2012 | Uncle Ben |
| Q: What do you think of this? Thank you, Butch Thorntone E. Murray January 3, 2012 (Reference will ... A: The discussion is based on an analogy. Analogies are interesting and sometimes stimulating to the ... | ||
| speed of light | 1/3/2012 | Uncle Ben |
| Q: This is probably a dumb question. Thank you for your patience. I think I understand the ... A: Joan, don't ever hold back from asking a question just because you are afraid that it might be ... | ||
| Light-speed | 12/15/2011 | Uncle Ben |
| Q: It seems to be strongly implied in SR, but I just want to confirm: would abandoning the inertial ... A: John, on the grand scale of stars, galaxies, and groups of galaxies, the speed of light is not ... | ||
| Mass | 12/10/2011 | Uncle Ben |
| Q: What is a mass(confused with definition of mass)? How it is measured? Is there any special apparatus ... A: Shaking an object is not a practical way to measure mass. It is easier to compare masses with a ... | ||
| Choosing a book | 12/10/2011 | Uncle Ben |
| Q: I need a book that teaches UG physics from the basic(in a clear way), that includes mathematical ... A: Since you are a smart fellow, the best book for you may be the Feynman Lectures, vol. 1, and other ... | ||
| Mass | 12/5/2011 | Uncle Ben |
| Q: What is a mass(confused with definition of mass)? How it is measured? Is there any special apparatus ... A: Shameem, "mass" is a property of an object that describes how hard it is to accelerate it. For ... | ||
| Speed of Light | 10/15/2011 | Uncle Ben |
| Q: Okay here we go. This is a question that has been bothering me for a while and I haven't received a ... A: Richard, that is a deep question, seriously. The serious answer is that if you push on the end of ... | ||
| speed relativity | 9/25/2011 | Uncle Ben |
| Q: Hey there! I was just reading about this neutrino that MAY have been travelling faster than the ... A: Your line of reasoning works well at low speeds compared to the speed of light, but part of ... | ||
| Changes imposed by spacetime upon high (relative) velocity inertial frames. | 8/24/2011 | Uncle Ben |
| Q: Three quickies (I hope!): 1) At relativistic speed an object gains mass/energy. Where does this ... A: 1) A boy rides a bicycle starting from rest. At 10 kph he has gained energy. Where does the extra ... | ||
| Lorentz theorem | 8/18/2011 | Uncle Ben |
| Q: Why do we add this certain amount under root 1-v(square)/c(square)? ANSWER: Sora, the answer comes ... A: Of course, Sora. I am happy to chat with you. To synchronize two clocks means to set them to read ... | ||
| Lorentz theorem | 8/18/2011 | Uncle Ben |
| Q: Why do we add this certain amount under root 1-v(square)/c(square)? ANSWER: Sora, the answer comes ... A: Sora, a frame of reference is only a coordinate system in space plus a system of synchronized ... | ||
| Relativistic mass | 8/17/2011 | Uncle Ben |
| Q: Sir, why do we use the term "relativistic mass"? Does that mean that mass also changes from one ... A: Sora, historically, the term relativistic mass was used. The phenomenon is that a particle subject ... | ||
| Lorentz theorem | 8/17/2011 | Uncle Ben |
| Q: Why do we add this certain amount under root 1-v(square)/c(square)? A: Sora, the answer comes from the requirement that the speed of light be the same in all inertial ... | ||
| Past as another dimension | 8/16/2011 | Uncle Ben |
| Q: I want to ask something that occured to me few days ago. I have been thinking, we always feel the ... A: The way you pose the question makes it a question in psychology, not physics. Time dilation has ... | ||
| Where to Start | 7/25/2011 | Uncle Ben |
| Q: I am 17 and my school does not offer any courses on relativity, or physics for the matter. I want to ... A: Aaron, you are a courageous student! Relativity is not an easy subject. But if you choose to go ... | ||
| Rest Mass | 7/20/2011 | Uncle Ben |
| Q: Uncle Ben, I see the term "rest mass" used quite a bit. What is its definition? Literally, rest ... A: Mike, first you need to define a frame of reference. For many everyday purposes, the earth can ... | ||
| Special Relativity and Mass-Energy | 7/20/2011 | Uncle Ben |
| Q: Uncle B, If an observer in any frame of reference traveling at uniform speed measures the speed of ... A: What does the spacecraft experience? The spacecraft is at rest with respect to itself, just as it ... | ||
| Special Relativity | 7/19/2011 | Uncle Ben |
| Q: I continue to ponder at the speed of light being invariant (in a vacuum) and measured the same by ... A: I gather from your example, Mike, that you are puzzled as to how a given object can have different ... | ||
| Special Relativity | 7/17/2011 | Uncle Ben |
| Q: I continue to ponder at the speed of light being invariant (in a vacuum) and measured the same by ... A: Mike, maybe I understand your question better now. I think I can help you. 1. Given a launch ... | ||
| Special Relativity | 7/16/2011 | Uncle Ben |
| Q: I continue to ponder at the speed of light being invariant (in a vacuum) and measured the same by ... A: Original answer: (See below for more.) Mike, you need to understand what it means for something to ... | ||
| relativistic momentum | 7/15/2011 | Uncle Ben |
| Q: Sir,i want to ask ur good self that when time dilation occur, the time between the two events w.r.t ... A: (1) If m is the rest mass of an object, its momentum is mv/(1 - v^2/c^2)^0.5. (2) The formula is ... | ||
| Time dilation | 7/14/2011 | Uncle Ben |
| Q: Sir,i want to ask ur good self that when time dilation occur, the time between the two events w.r.t ... A: Tufail, you say that the space crafts clock is moving slowly. But motion is relative. The space ... | ||
| Time dilation | 7/13/2011 | Uncle Ben |
| Q: Sir,i want to ask ur good self that when time dilation occur, the time between the two events w.r.t ... A: Tufail, you are correct. But I want to emphasize a few things: The two clocks are not changed ... | ||
| Theories | 7/11/2011 | Uncle Ben |
| Q: I’m going to start off by saying; I have had some physics in the past. I am looking forward to ... A: Robert, I am glad that you are interested in physics enough to compose alternate theories. ... | ||
| Dual nature of matter | 6/28/2011 | Uncle Ben |
| Q: A metal has a threshold wavelength.Suppose, a light of wavelength less than that of threshold ... A: Equal intensity means equal energy. The energy of a *single* photon depends on its color, or ... | ||
| FTL travel | 6/13/2011 | Uncle Ben |
| Q: Ben the last expert could not help me with this so I'm hoping you can. I'm kind of an amateur ... A: John, I expect that there is no expert who can give you a good answer to your question. First, ... | ||
| relativity | 6/3/2011 | Uncle Ben |
| Q: A 1000-kg automobile moving with a speed of 24 m/s relative to the road collides with a 500-kg ... A: Moe, this question can be answered by a high school physics student who knows nothing about ... | ||
| cosmological relativity. | 6/2/2011 | Uncle Ben |
| Q: I wanted to ask a follow up. I read that the theory of cosmological relativity naturally predicts ... A: A.J., I can't answer your question because I don't know enough about "cosmological relativity" and ... | ||
| Anti-matter spectrum speculation | 5/30/2011 | Uncle Ben |
| Q: I love to get speculation from physicists, in part because they either A. absolutely love it, or B. ... A: Mike, it doesn't take much speculation to predict, on the basis of good theory, that the EM spectra ... | ||
| Special and general relativity | 5/27/2011 | Uncle Ben |
| Q: I had a question regarding DR. Moshe Carmeli's theory of Cosmological relativity where the starting ... A: AJ, This theory is something very new to me, and I will not be able to give you a clear answer. It ... | ||
| special relativity | 5/19/2011 | Uncle Ben |
| Q: I wanted to know if this guy is right? http://www.milesmathis.com/long.html ... A: A.J., for the interesting question. The first link you give, ending in "long.html," refers to a ... | ||
| Looking for expert to discuss theory | 4/19/2011 | Uncle Ben |
| Q: I realize this is an unusual question and possibly not the right forum but I thoughtg you might ... A: Brian, as you may be able to see, AllExperts cut out the email address you entered. They do not ... | ||
| Looking for expert to discuss theory | 4/19/2011 | Uncle Ben |
| Q: I realize this is an unusual question and possibly not the right forum but I thoughtg you might ... A: Brian, you have certainly proved that you are serious! Perhaps the following will serve your ... | ||
| Theory of relativity | 4/10/2011 | Uncle Ben |
| Q: I can't understand theory of relativity. Its beyond common sense. How can time differ in different ... A: You are correct, Sora. Time does not depend on our observations. This is not psychology! Let me ... | ||
| Lorentz contraction | 4/5/2011 | Uncle Ben |
| Q: I take it that I have to continue the conversation through All Experts again. I assume that you ... A: Franco! I am answering this because AllExperts needs to clear their files. I hope you already have ... | ||
Uncle Ben
Top Expert on this page
Expertise
I can answer questions regarding Einstein's Theory of Relativity, particularly in Special Relativity. I will not answer homework questions or mathematical problems that require special symbols.
Experience
I have taught physics at the college level, undergraduate and graduate, for many years including Special Relativity. I have taught at Johns Hopkins, Case-Western, and MIT. I have also served as a staff member of the Commission on College Physics, which was supported by the National Science Foundation to recommend improvements in the curriculum of college physics departments in the US. I am also the author of a textbook titled Vector Calculus, which was used at MIT in the teaching of electromagnetic theory and relativity. My research interests were mainly in solid state physics, especially the properties of metals at low temperatures. I am listed in the publication known as American Men of Science.
Publications
I have dozens of papers published in the Physical Review and in the American Journal of Physics.
Education/Credentials
I hold a Ph.D. degree in physics from the Johns Hopkins University.
Past/Present Clients
Johns Hopkins University, Case-Western Reserve University, Massachusetts Institute of Technology, Empire State College, Georgetown University, Commission on College Physics, and UNESCO.
©2012 About.com, a part of The New York Times Company. All rights reserved.