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. E

    Question about Einsteins theory of relativity

    I have a question about einsteins theory of relativity. he stated, that speed described by *constant* c (0.3Gm/h) is equal, no matter what observer you choose. imagine this scenario: observer A - a guy on earth, sitting in the lab chatting with B observer B - a guy on sace ship that that...
  2. S

    Exploring General Theory of Relativity

    is it possible to get accurate results of general theory of relativity without retaining the concept of four dimensional curved space
  3. S

    Special Theory of Relativity Need help, Urgent?

    Homework Statement An observer in frame S standing at the origin observes two flashes of coloredlight separated spatially by delta x=2400 m. A blue flash occurs first, followed by a red flash 5 microseconds later. An observer in S' moving along x-axis at speed v relative to S also observes the...
  4. S

    Accurate Results of General Theory of Relativity

    is it possible to get accurate results of general theory of relativity without discarding concept of three dimensional flat space
  5. S

    Mobile communication with electromagnetic waves and theory of relativity

    Since the combined speed of electormagnetic waves can be 'c' and that they travel in space at 'c' leaves no component for time, hence the time on a watch on a beam of electromagnetic wave does not change at all. With this understanding, assume two stationary mobile phone users U1 and U2...
  6. P

    Theory of relativity second postulate

    Hi, the theory of relativities second postulate is:- The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the source of the light A physical process occurs when a photon is being emitted and this process takes place at...
  7. T

    Exploring Einstein's Theory of Relativity: Can Time Travel Be Possible?

    Time time time Can the laws of gravity permit curving space and time in such a way as to make time travel possible. Einstein's theory of relatively states that the space/time continuum can be flat, but it can also be curved by gravitational fields. Perhaps time has three folds 1...
  8. D

    Thinking bout the Special Theory of Relativity

    I understand that Einstein derived his Special Theory from two assumptions: 1. That classical physics holds in all inertial frames 2. That the speed of light will always be measured to be the same. So, what I was trying to do was to derive the equations starting out from these two...
  9. D

    Eintein's theory of relativity

    i would like to know in context to Eintein's theory of relativity if it is actually possible if someone was in a train traveling at the speed of light, and they held up a mirror is it possible that, that person would be able to see their own refelction? umm also in a paradox, if one twin was...
  10. J

    General theory of relativity space without ether is unthinkable

    ”According to the general theory of relativity space without ether is unthinkable; for in such space there not only wonld be no propagation of light, but also no possibility of existence for standards of space and time“...this in an statement given by einstein...please tell me what is the ether...
  11. Z

    Simultaneity - Albert Einstein and the Theory of Relativity

    The following is the Einstein’s train but instead of train consider two airships of equal in lengths. http://www.youtube.com/watch?v=wteiuxyqtoM&feature=related Both are moving with same speed but opposite in direction. After certain time they cross each other such that one is exactly...
  12. G

    Questions about light, theory of relativity

    Ok, I don't know all there is to know about the theory of relativity, so with that said, hopefully someone can answer this question! How can light always move away from its source at a constant speed speed? In other words, let's say the speed of light is 5+. That means that light is always 5...
  13. N

    Accelerated obserevers in special (not general) theory of relativity

    Hi, folks! I am interested for the following question: The original Einstein's formulation of the special theory of relativity does not permit consideration of the accelerated observers, but this limitation is not essential because we can consider the special relativity as limit case of...
  14. I

    Current Applications of the Theory of Relativity?

    Einstein's theory of relativity (special and general) changed dramatically physics at his time, and is still has not lost ground. But concerning it's practical sides, what are it's applications, or consequenses in today's "everyday life"? Of those I have found, fission and fusion (I...
  15. R

    Does the theory of relativity include angular motion?

    Does the theory of relativity include angular motion? Say we have one body synchronously orbiting a motionless body. It can also be viewed as two motionless bodies and one is spinning while the other is not. (i.e. if you were on the moon staring at earth, you would not witness orbital...
  16. B

    Uniting quantum physics with the theory of relativity

    Uniting quantum physics with the theory of relativity is not possible. What are the problems / challenge?
  17. J

    Whom do we consider as moving in special theory of relativity?

    hey guys... i have understood the part of special theory of relativity where they explain why the time slows down for a guy moving with greater speed.. or atleast i think i have understood. But the problem is that suppose two guys are in the space one guy is moving at a high speed and the other...
  18. M

    General Theory of Relativity ?

    As a beginner which book should i study for GTR & does it require to have knowledge of tensor algebra ? If yes then suggest me a book for that too .
  19. A

    Special Theory of Relativity

    Homework Statement A carpenter on a space statopn has constructed a 30 degress ramp. A rocket moves past the space station with a relative speed f 0.730c in a direction parallel to the horizontal. What does a person above the ocker measure for the angle of the ramp? Homework Equations...
  20. D

    True/False: Theory of Relativity Questions

    You fly in a 747 across the Atlantic from Amsterdam to Detroit at about 900 km/hr. Effects of the Theory of Relativity are of course unnoticeable at such speeds, but just as a thought experiment—which of the following are true? 1. The walk from your seat to the restroom actually becomes...
  21. R

    Is Traveling at the Speed of Light Impossible?

    use the equation m=mo/sqrt(1-v^2/c^2) to show that traveling at the speed of light or beyond is impossible.
  22. R

    What is the effect of increased spacecraft speed on astronaut's pulse rate?

    what effect would increasing the speed of the spacecraft have on the astronaut's pulse as measured by the astronaut and by the Earth observer? why. I think in both measurements, an increased pulse rate will be found?..
  23. R

    Specialy theory of relativity

    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?
  24. M

    Why do time, distance, and mass change in Einstein's theory of relativity?

    Alright, i have a final and i have to explain just three parts to einstein's theory of relativity... they are space travel (time slowing nearing the speed of light), increase of mass with speed, and length contraction... the space travel makes no sense, and the mass one, i have mixed feelings...
  25. E

    Understanding Surface Tensors: Pauli's Theory of Relativity

    I'm reading through Pauli's "Theory of Relativity", which has a discussion of tensors in the mathematical tools section of the book. When introducing surface tensors, he states "Such tensors can be obtained by considering two vectors x, y which together span a two-dimensional parallelepiped...
  26. B

    Calculating Speed in Special Relativity: A Grade 12 Physics Problem

    Thanks for taking a look. The following question is that is that from a grade 12 academic physics course. Homework Statement Scientist Ludwig von Drake, while in his laboratory, measures the half-life of some radioactive material which is in a bomb, approaching with speed v. Donald Duck, who...
  27. S

    Einsteins Theory of relativity Equation help

    For my science fair project I decided to test Einsteins Theory of relativity. Upon searching for hours on the internet I know that I'm supposed to be finding the velocity of a particle. I'm told the equation is the magnetic rigidity times ratio of electrons charge to mass times the square root...
  28. H

    Questions concerning the Theory of Relativity, sound, and light.

    Hello again. Been working on the online homework and I'm somewhat stuck with one of the problems. With the other one, I would just like to confirm I have the correct idea in mind. Thanks! First the question which I am having the problem with. 1) In which of the following statements...
  29. G

    What is the theory of relativity?

    I'm trying to understand the theory of relativity can someone tell me (in English!) if I'm close to correct. The theory of relativity says that the closer you get to the speed of light the faster time goes (i think someone said it was impossible to get to the speed of light) e.g two...
  30. P

    Einstein's Special Theory of Relativity: Beam Angle

    Would the beaming effect suggest that if a light source is moving at close to speed of light (shining toward me) as seen by me (so I am in the lab frame) than I will see the angle of the beam larger than what a person in the moving source frame would see it?
  31. I

    Einstein's theory of relativity?

    Einstein's theory of relativity? In Length contraction and Time dialation, the distance between the two frames is also a determining factor. i guess so but why do they are not taken into account. why they are not included in the equation? I mean in m =[mo/root of one minus V^2/c^2]...
  32. U

    =Special Theory Of Relativity=

    Ok. Let's say a fan is spinning at the speed of light. ( Imagine folks;) If i shine a light ray towards it, light would be able to pass through it almost instantaneously. Let's disregard one law of special theory of relativity stating that objects traveling at the speed of light would have 0...
  33. A

    Concerns about ontological interpetations of Theory of Relativity

    First of all, browsing this forum, I feel that the level of competence regarding theory of relativity is higher than on average science forums. It may not be much to say, but the only reason I want to post here is because I believe criticism and comments might actually come from people who KNOW...
  34. M

    Theory of relativity and time

    I need further explanation on the following so I can understand it more completely. I know that the theory of relativity /space and time are connected with the invention of the syncoronized clock and time zone division, and that Einstein originally used train travel to explain his theory (I am...
  35. D

    Place to discuss the Theory of Relativity

    I read this and I'm not sure if this is the right place to post. If it isn't then I appologise. An object in space accelerates to 2/5 th the speed of light and then stops accelerating traveling at a steady pace. If it doid this 3 times it would travel 1.2c. Now, if something cannot go...
  36. G

    How would you explain the Special Theory of Relativity using Physics?

    Everywhere I read, they are all about the history of the theory or the impact, I can't find a site that actually uses Physics concept to explain it.
  37. C

    Is the General Theory of Relativity Worth Learning from a Troll?

    I am interested in learning the general theory of relativity, and I want to know if someone here would be willing to take the time to teach it to me. I have heard that it is a theory of gravity. On the down side I don't know tensor mathematics very well, nor do I like it, but on the up side I...
  38. L

    Theory of relativity - spacetravel

    I failed this question on my exam :mad: , would appreshiate someone helping me figuring out a correct answer :smile: "Suppose a person on planet X, 10 lightyears away from Earth, sends a readiomessage traveling with the speed of light. An astronomer leaves planet X in a spaceship, at the...
  39. D

    Foundation to the theory of relativity

    Hey, i don't know if this is the right spot to post this question, but I was reading "The Universe in a Nutshell" by Steven Hawkins. Got through the first few pages. I am just wondering what is "Einstein's postulate that the laws of nature should appear the same to all freeli moving observers...
  40. S

    Theory of relativity sets limits

    einstein's theory of relativity sets limits on speed, saying it cannot be greater than c, the speed of light. What does this imply for the limits of momentum and energy?
  41. C

    NASA To Test Einstein's Theory of Relativity

    http://www.azom.com/news.asp?newsID=1230 interesting.
  42. M

    Major Breakthrough in Theory of Relativity

    http://individual.utoronto.ca/News_1/Key134/Theory_Relativity_Breakthrough.htm
  43. benzun_1999

    Can anyone explain the theory of relativity to me

    dear reader, Can anyone explain the theory of relativity to me. benzun all for god
  44. Eugene Shubert

    Absolute Space and Time in Einstein's General Theory of Relativity

    The Special Theory of Relativity, we teach our students, did away with Absolute Space and Absolute Time, leaving us with no absolute motion or rest, and also no absolute time order. General Relativity is viewed as extending the "relativity of motion" applicable to curved spacetimes, and General...
  45. M

    Understanding of the theory of relativity

    a vauge question: i am, admititly, far from a complete understanding of the theory of relativity and special relativity but could someone humor me by explaining exactly why the T.ofR. perdicts its own break down at a singularity.
  46. R

    Einstein's General and Special Theory of Relativity

    i have a few questions about both of these theories that Einstein wrote. 1. Was one of these theories tested against 2 atomic clocks, one which is on Earth and the other on a fast jet going around the earth, both clocks syncronised and the results were different, which theory was tested with...
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