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# Relativity/Further question on relativity

Question
Hi,

Thanks for your reply. I thought theory of relativity is applicable only in case of bodies moving with light speed. I would like to know why the relativity is applied to  satellite clocks when the satellites are running much slower than light. Also you wrote that muons decay time gets increased when they travel faster. How could we conclude that it was because of velocity and time slowing, muons decay time got longer. There could be n number of reasons why there decay got longer which the science has not yet found. Also could the slowing of clock be due to difference in gravitational pull, atmospheric conditions etc. Why should we e necessarily assume that "time" got slower. Also I find it illogical to believe that we can move to past or future in time because of relativity. Just because clock runs slower, how could we arrive at illogical conclusions.

No, relativity applies to all of physics. The effects of relativity show up strongly only when we observe fast objects, but relativity applies even to slow objects;  it is just that for slow objects, the difference between relativistic theory and classical theory is tiny.

But in the case of electrical forces, they are so strong that even slow currents can cause effects that we can easily see in everyday life. We call the motion effects "magnetism." Magnetism is a relativistic effect of moving charges. This understanding came after Einstein discovered Special Relativity. He came to discover relativity because he was trying to understand magnetism.

We cannot move into the future by means of motion with any ability to profit from it. There are limits to how far we can see into the future.

Relativity is a deep and difficult subject, but it has been confirmed many times by experiment.  To understand it fully requires a long study. All professional physicists have studied it and its experimental tests, and almost all have found it essential in modern physics. The exceptions are nowadays considered cranks.

Ben

Relativity

Volunteer

#### Uncle Ben

##### 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.