6th Apr 2013
A Photon’s Universe
Special relativity gives us the famous formula that tells us energy can be equated to mass: e=mc^2, where e is energy, m is an object’s mass, and c is the speed of light in a vacuum—the maximum speed limit of the universe. Basically, this simple equation tells us that the faster an object travels, the more massive it becomes. As is approaches the speed of light, an object becomes more and more massive and so more and more energy is required to keep it in motion—which is why it’s impossible for anything with mass to reach the speed of light. Only the particles that carry light, photons, can travel at the speed of light—because they’re massless. Special relativity also tells us that time is relative to the observer. If Person A is standing still and observing Person B run a race, the time that elapses between the start and finish isn’t the same for both of them—time depends on the relative speeds of their reference frames. The faster you travel, the slower time goes for you—if you’re holding a clock, it will tick slower. The closer you are to the speed of light, the slower time ticks, and when you’re actually travelling at the speed of light, time won’t pass at all. Photons, therefore, don’t experience time. To us, light travel extremely fast, but it still takes time for it to travel (299,792,458 m/s)—but that’s relative to our reference frame; our place as an observer. To photons, they leave one place and arrive at their destination in the exact same instant. To photons, the universe begins and ends at the same time.

(Image Credit: BBC)

A Photon’s Universe

Special relativity gives us the famous formula that tells us energy can be equated to mass: e=mc^2, where e is energy, m is an object’s mass, and c is the speed of light in a vacuum—the maximum speed limit of the universe. Basically, this simple equation tells us that the faster an object travels, the more massive it becomes. As is approaches the speed of light, an object becomes more and more massive and so more and more energy is required to keep it in motion—which is why it’s impossible for anything with mass to reach the speed of light. Only the particles that carry light, photons, can travel at the speed of light—because they’re massless. Special relativity also tells us that time is relative to the observer. If Person A is standing still and observing Person B run a race, the time that elapses between the start and finish isn’t the same for both of them—time depends on the relative speeds of their reference frames. The faster you travel, the slower time goes for you—if you’re holding a clock, it will tick slower. The closer you are to the speed of light, the slower time ticks, and when you’re actually travelling at the speed of light, time won’t pass at all. Photons, therefore, don’t experience time. To us, light travel extremely fast, but it still takes time for it to travel (299,792,458 m/s)—but that’s relative to our reference frame; our place as an observer. To photons, they leave one place and arrive at their destination in the exact same instant. To photons, the universe begins and ends at the same time.

(Image Credit: BBC)

This post has 509 notes
  1. elwethingol reblogged this from sciencesoup
  2. starphyx reblogged this from sciencesoup
  3. putmyfaithinthestars reblogged this from brightestofcentaurus
  4. dust-and-air reblogged this from brightestofcentaurus
  5. gentleless reblogged this from brightestofcentaurus
  6. brightestofcentaurus reblogged this from quietcoimetromaniac
  7. quietcoimetromaniac reblogged this from sciencesoup
  8. strawberryon reblogged this from sciencesoup
  9. bazook reblogged this from ne0ndreams
  10. laughlinesforcutie reblogged this from sciencesoup
  11. sir-meow reblogged this from indicarain
  12. leftoverbatmans reblogged this from sciencesoup
  13. dohmatic reblogged this from ceruleanknight
  14. ceruleanknight reblogged this from sciencesoup
  15. trmilson reblogged this from sciencesoup
  16. emmanuel-avila reblogged this from sciencesoup
  17. dafuturedoc reblogged this from sciencesoup and added:
    Physics
  18. the-jamjam reblogged this from sciencesoup
  19. seriesofcontemplation reblogged this from sciencesoup and added:
    A Photon’s Universe Special relativity gives us the famous formula that tells us energy can be equated to mass: e=mc^2,...
  20. parasergrandeseinteiro reblogged this from sciencesoup
  21. larshh reblogged this from sciencesoup
  22. siljyon reblogged this from transfixussednonmortuus
  23. transfixussednonmortuus reblogged this from anengineersaspect
  24. anengineersaspect reblogged this from sciencesoup
  25. jvdbooks reblogged this from sciencesoup
  26. jokestuh reblogged this from sciencesoup
  27. nicotine-aspartame reblogged this from antitau
  28. comrade-snarky reblogged this from sciencesoup