What is Theory of relativity: Definition and 146 Discussions

The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to other forces of nature. It applies to the cosmological and astrophysical realm, including astronomy.The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction. In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in the nuclear age. With relativity, cosmology and astrophysics predicted extraordinary astronomical phenomena such as neutron stars, black holes, and gravitational waves.

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  1. S

    Special theory of relativity: velocity of airplane

    Homework Statement If a clock in an airplane is found to slow down by 5 parts in 1013, (i.e. Δt/Δto = 1 + 5x10-13), at what speed is the airplane travelling? (Hint: You may need to use the binomial expansion for γ.) To be honest, I'm really confused about what this question's telling me...
  2. N

    The theory of relativity by Christian Møller

    I stumbled upon this text recently and I was just interested in how you'd rate it, in case you're familiar with it. To me the exposition seems alright, but the text is old and sometimes it shows. Would you consider learning relativity from this book as a main source or would you go for a more...
  3. P

    General and special theory of relativity in few words

    How can I explain to someone who has only high school level of education in physics, what is general and special theory of relativity about? Each of them separetelly in one or two sentences please. General theory of relativity … Special theory of relativity ... Thank you.
  4. R

    Newton's law of gravity or Einstein's general theory of relativity?

    I don't know much about the two ideas but I'm confused because the two theories seem to contradict each other, if all matter (with mass) bends space, then there is no such thing as "gravity", or maybe gravity is just the actual bending of space, so should we refute the idea of "gravity"? or just...
  5. N

    Did Einstein Discover the Theory of Relativity

    I read somewhere recently that Einstein did not discover the Theory of Relativity. If he didn't, who did? And why is Einstein given credit for the Theory of Relativity?
  6. ash64449

    Exploring Minkowski Space: Understanding Special Theory of Relativity

    Hello friends, I am reading Einstein's special theory of relativity and came across this subject: Minkowski space. I cannot understand exactly what it is when i read that book and went to Wikipedia for understanding more about it. But i didn't understand much. What i...
  7. ash64449

    Doubts in general theory of relativity

    according to equvalence principle,acceleration can be equvalent to rest in which gravitational field exists. Earth revolves around the sun as sun produces curvature in space-time. What kind of acceleration is the curvature of space-time produced by sun equavalent too?
  8. ash64449

    Doubts in special theory of relativity

    Hello friends, From special theory of relativity,it is understood that if two events are simultaneous to a stationary reference frame,it is not simultaneous to a reference frame that is moving uniformly in straight direction. Is opposite possible? That is are two events are simultaneous to a...
  9. Feodalherren

    Show that m varies with v in theory of relativity

    Am I supposed to take dm/dv? That means m0 is constant, correct? If I do that I end up getting a m' on the Left hand side... What the heck does that mean?! Also where the crap is the "a" coming from?!
  10. V

    Why is the theory of relativity a theory?

    Why is the theory of relativity a theory? Haven't we proven one of its consequences (time dilation) already using atomic synchronized clocks?
  11. Saitama

    Theory of relativity - proton entering a medium

    Homework Statement (see attachment) Given data: 1.The speed of light in empty space is ##3 \times 10^8 m/s##. 2.The mass of the proton is ##1.67 \times 10^{-27} kg## . 3.The speed of light in water is ##2.3 \times 10^8 m/s##. 4.When photon emission begins to occur the initial proton, the final...
  12. S

    Theory of Relativity VS. Relativity to placement

    Being new on this site I've decided to post a question that has echoed through my head for a while now. If Einstein's Theory of Relativity literally claims that all actions and reactions are relative to the observer, then how do we as humans measure anything at all without being at any constant...
  13. D

    Is the speed of light the same for all observers?

    Is this statement true? The speed of light (about 300,000,000 meters per second) is the same for all observers, whether or not they're moving. If so could someone please explain it to me, because it was my understanding that if an object was moving at a constant velocity it would appear to be...
  14. J

    What motivated Einstein to start thinking about a General Theory of Relativity?

    So basically I have always wondered what motivated Einstein to move from Special Relativity to General Relativity. Anyone care to tell me what was going on in Einsteins mind after he completed his Special Theory of Relativity? I have done a course in Special Relativity, understand it and I...
  15. T

    Theory of Relativity, a poor name?

    Do you agree that “The Theory of Relativity" is a poor name? According to Mauldin in "how the trick may be done": "It has long been remarked that “The Theory of Relativity” is a poor name for the Theory of Relativity. The usual justification for the name looks backward to pre-Relativistic...
  16. Y

    I don't get the Theory of Relativity

    How did it become so famous when it's so hard to understand?
  17. N

    Paper about special theory of relativity

    Hi there, I'm doing a paper about the special theory of relativity. The paper consists of two parts: - explaining the theory - explaining what kind of consequences the special theory will encounter, if particles move faster than the speed of light. Where does the theory fail? I've...
  18. G

    Confused about Special Theory of Relativity?

    Hi, I have a question (or maybe more) about special relativity. I'm reading The Fabric of the Cosmos by Brian Greene right now, and what I got from one of the sections is confusing. I might be understanding it wrong, or maybe what he's saying is wrong, or maybe it's just right. So this is what...
  19. L

    How to explain Einstein's Special theory of Relativity.

    Can someone help me with understanding and explaining the Special theory of relativity. I know the basics (time dilation, the speed of light, ect), just what's left is Lorentz transformation and I'll understand the theory. And also help with explaining the theory to a friend. And help...
  20. estro

    Special Theory of Relativity and Lorentz T. question

    Homework Statement Particle mu was created in the atmosphere and traveled 2km relative to Earth with a speed of 0.8c. Particle e was created in the same time and traveled parallel to mu with the speed of 0.6c. How much distance mu traveled relative to e? Homework Equations Lorentz...
  21. majormuss

    Modern Physics (S. Theory of relativity) problem

    Homework Statement Find the force necessary to give a proton an acceleration of 1.0 10e19 m/s2 when the proton has the following velocities (along the same direction as the force). Homework Equations P=mλu The Attempt at a Solution Found the derivative of the above equation and...
  22. Government$

    Special Theory of Relativity question

    Homework Statement I took this form Yale Open Course Homework Equations Special Relativity equations The Attempt at a Solution I will try to divided this problem into two parts: First one is - what is its location in my frame when it ticks 1 second in its frame? and second one - If...
  23. R

    Einstein's Theory of Relativity: Why Planets Orbit Quicker Near the Sun

    Einstein predicted a slightly quicker orbit for planets very close to the sun that will deviate from Newton’s gravitational laws very slightly. Later observations, as we know, have proved correct and General Relativity holds up. But what is the perceived reason as to why this is? What is the...
  24. I

    Special theory of relativity- V.A.Ugarov

    Hi here is a great book on special theory of relativity...uploading front cover. good thing is that there is no copy right... it was published in soviet union by Mir Publishers , Moscow which is now gone...So let me know if anybody wants this...I have it...most of the books published by...
  25. F

    Will The Theory of Relativity allow me to travel Backwards in Time?

    Hello, I have been wondering about this for a bit of time now, but forgive me for not being entirely clear with this, if that does happen. I once heard that the relativity of space and time is like a graph. If you are not moving in space, that does not affect your time, with space being on...
  26. M

    Was gravitational length contraction predicted by general theory of relativity ?

    I have read somewhere about the phenomenon called gravitational length contraction.Was gravitational length contraction predicted by general theory of relativity?
  27. J

    How is the big bang related to the general theory of relativity?

    hi guys, I've read a few articles that say that einstein's general relativity paved the way for the big bang theory. Can anyone explain how they are connected?
  28. A

    General theory of relativity clearly explained

    I m new to general theory of relativity,so I would like to study it but wikipedia has so many links which is really difficult to sort..Anyone please suggest a better link so that I can learn GR without any difficulty.THANKS IN ADVANCE
  29. P

    Reframing the Special Theory of Relativity

    The question: is the following statement true or false? "If the Special Theory of Relativity is re-framed so that instead of c being constant, distance or time is the constant, it remains valid."
  30. G

    What is the conflict between General theory of relativity and Quantum theory?

    General relativity and Quantum theory are two pillars of physics... The unified theory concept trying to combine 4 basic forces of nature. I don't know what is the actual conflict between gravitational force and other 3 forces?
  31. C

    Learning Material for General Theory of Relativity

    I am beginner to General Theory of Relativity. Please do suggest any good books, so that I can learn on my own. Anyone, please... If the book is an Indian Edition its very fine.. Thanks in advance to all..
  32. M

    How to find that the universe is expanding from general theory of relativity

    1 how to find that the universe is expanding from general theory of relativity 2 how to apply general theory of relativity to find that the universe is expanding
  33. S

    A thought experiment with theory of relativity.

    Hi, I had a question on theory of relativity. It is more of a thought experiment. As per the theory of relativity, as the speed of an object increases time slows down. If any particle travels faster than the speed of light, theoretically it has to travel back in time. So from this we can...
  34. A

    Theory of relativity challenged

    What would happen if Theory of relativity is abolished or challeged? As the news is coming that Neutrino is supposed to cross the speed of light , what would happen to the physics laws when this discovery proved by scientists. Plz give some examples .. Of physics laws .. Which physics laws...
  35. N

    Is Special theory of relativity only about speed of light?

    I am a beginner in this field. I have read Special theory of relativity by Einstein, but the one written for beginners, not the technical. I have also read couple of undergraduate books which had STR. From my understanding, STR is a theory about transformation from one frame to another, both...
  36. micromass

    PF Logo Contest: Theory of Relativity

    Theory of Relativity The theme of this contest will be the theory of relativity, and in particular the equation E=mc^2. On 27 september 1905, Einstein published the paper in which the famous equation E=mc^2 first appears. This contest will end on 15 september. This way we will have enough time...
  37. L

    Special theory of relativity question

    A “light clock” consists of a mirror, a light source and a light detector. The light source and detector are very close to each other and both are at a distance ‘L’ from the mirror (or the mirror’s plane). In an inertial frame at rest, a light pulse is emitted from the light source...
  38. K

    Is it possible for relative velocity to exceed the speed of light?

    Let there be a space shuttle moving at very high speed relative to Earth so, actually time would be slower in the shuttle than on the earth.But, if we see everything relative to shuttle then, Earth is moving at very high speed that, means Earth is slower. These two things are contradicting. So...
  39. C

    Does Einstein's Theory of Relativity Substantiate the idea of Time Travel?

    Ronald Mallett, PhD is a renowned physicists known for his proponents on the idea of time travel. Mallett uses his background in physics and mathematics to support his idea to build a time machine, using Einstein's Theory of Relativity as a basis. Do you think this is even possible? Right...
  40. A

    Specialy theory of relativity [Answer Check]

    Homework Statement a 30-year old female astronaut leaves her newborn child on Earth and goes on a round-trip voyage to a star that is 40light-years away in a spaceship traveling at 0.90c. what will be the ages of the astronaut and her son when she returns? Homework Equations \Delta t =...
  41. A

    Which Principle of Relativity is the Most Profound in Einstein's Special Theory?

    Hello PF Folks. So Einsteins Special Thoery of Relativity is based upon two principles (im shortening them for speed and effort): 1) Speed of light in a vacuum is independant of the motion of the source 2) Same laws of Physics apply in all inertial frames of reference. My question is...
  42. S

    Tensor Calculus General Theory of Relativity

    Hello I have huge problems with the following exercise. Please give me some hints. No complete Solutions but a little bit help. Find the differential equations of the paths of test particles in the space-time of which the metric ist \mathrm{d}s^2 = e^{2kx} \left[- \left( \mathrm{d}x^2...
  43. F

    Do you know how to derive the General Theory of Relativity?

    I am trying to get the coeficient gamma=1/squareroot(1-(v/c)2) I am trying to do this by my own knowledge starting from scratch. Can someone give me the first step? I want to see if i can get there but i just need a hint i am not sure on where to start Thankyou very much, Fox
  44. E

    Einstein's Theory of Relativity: What if E=mc2 Was Wrong?

    Okay, now I know something like this may seem improbable. But what would happen if Einstein's theory of E=mc2 was wrong?
  45. M

    Question about the theory of relativity.

    Hello, I am fairly new to quantum physics and I recently became interested in Einstein and his accomplishments b/c I never knew why he was considered a genious and I was curious... So, I took a few minutes to try to understand the way the theory of relativity works, which by the way, I am...
  46. Sirsh

    Special theory of relativity

    Hello all, I just need some help understanding inertial frame of reference, is this when there is no acceleration acting on a body. such as, gravity.. but the body can be under constant velocity or at rest. Also, Could someone please help me with this senario: there is a guy in a rocket...
  47. I

    A question about the theory of relativity

    Homework Statement If I fly at the speed which is similar to the speed of light,and I am watching a still star,then because of the theory of relativity,the size of the star will change.If the size of the star turn to the size of a neutron star or a black hole,what will happen?Will I see a...
  48. W

    Albert Einstein's Theory of Relativity

    Hi, I'm really having a hard time grasping some of the concepts of this theory. Yes I'm not a really clever person but I enjoy learning and need abit of help. My question is probably very basic to you guys but I need some confirmation that I am thinking the right away about this. I have been...
  49. I

    Special Theory of Relativity Incorrect?

    I do not believe the Special theory of relativity is in correct, however the question did come up in class the other day. If some people do believe it to be incorrect, than what are some of these theories as to why it is in correct? I was just wondering and curious about the whole subject. I...
  50. B

    Special Theory of Relativity paper

    Hello! I'm writing a paper on Einstein's special theory and Einstein himself for my high school freshman science class; I was told this would be the best place to post it. I'm trying to make my explanation clear; if it's not, suggestions on how to improve it would be appreciated. Thanks! :smile:
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