Slashdot Mirror

← Back to Stories (view on slashdot.org)

100 Years of Special Relativity

Posted by Zonk on from the much-better-than-the-regular-kind dept.

phrotoma writes "Wikipedia notes in their Selected Anniversaries section that today marks the 100th anniversary of Albert Eintein's publication of the third of his four Annus Mirabilis Papers entitled On the Electrodynamics of Moving Bodies; the seminal work that introduced the concepts which would come to be known as Special Relativity. This event is also being commemorated in a UN endorsed celebration of physics: World Physics Year 2005 with talks and events at public schools, museums, and universities the world over."

57 of 299 comments (clear)

  1. 100 Years by Inkieminstrel · · Score: 5, Funny

    100 years according to which observer?

    1. Re:100 Years by RWerp · · Score: 2, Interesting

      Each object in the Universe has its own coordinate system (a thing equivalent to an observer), in which it is always at rest. To put it shortly, it's observing itself. The time measured in this coordinate system is called a proper time. I guess we can say that it's been ca 100 years of proper time of the manuscript of Einstein's article...

      --
      "Long run is a misleading guide to current affairs. In the long run we are all dead." (John Maynard Keynes)
    2. Re:100 Years by millennial · · Score: 3, Funny

      Due to special relativity, I accuse you of stealing my joke and posting it before I could.

      --
      I am scientifically inaccurate.
    3. Re:100 Years by Black+Parrot · · Score: 5, Funny


      > The first five posts are all riffs on the same theme -- dilation of time. Does that say more about the level of education among Slashdotters, or about our lack of creativity, or both?

      Maybe it's just one post arriving via gravitational lensing.

      --
      Sheesh, evil *and* a jerk. -- Jade
    4. Re:100 Years by AKAImBatman · · Score: 2, Interesting

      Arguably, space-time warping can be accounted for in a calendar as long as some sort of reference point is given. For example, if I left on a rocket ship at .95C, bound for Alpha-Centauri and returned 10 years later (Earth time), I could still say that ten years have passed on the Sol calendar based on the current positions of the bodies inside the solar system. The fact that the movement of those bodies occurred inside a period of only 8 years my time is irrelevant. 10 years has still passed according to the Sol calendar.

      Timekeeping is fun. Especially if you're a computer programmer. ;-)

      --
      Javascript + Nintendo DSi = DSiCade
    5. Re:100 Years by drsquare · · Score: 3, Insightful

      It happens with all vaguely-science related articles. Most Slashdotters are just kids who've managed to install Linux, they don't know much about science and technology. So when an article like this comes up, they've nothing informed to say. But they treat Slashdot as a chatroom, the social life they don't get in the real world. And they're desperate for attention, so they HAVE to post. Even if they have nothing to say. Especially if they have nothing to say.

      So we have kids, desperate to get a +5 funny to validate themselves, on an article they know nothing about. So what do they do? They try posting something 'hilarious', like a play on words of something in the article, or something starting with 'Did anyone else read this as...', or a reference to one of the tired slashdot memes, as if quoting Douglas Adams makes them one of the Slashdot 'in crowd'.

      It ruins it for the rest of us, as on any science article, we have to scroll half way down the page to get to the first person who actually says something relevent to the article.

  2. Pffft by kaellinn18 · · Score: 4, Funny

    I already read about this tomorrow.

    --

    --------
    This isn't the sig you're looking for. Move along.
  3. Like it was only yesterday by FunWithHeadlines · · Score: 2, Funny

    100 years? I don't understand. That paper was published just two years ago, right before I embarked on my intersteller voyage travelling near the speed of light. I've only been gone two years, so clearly one of us has calendar issues.

  4. No, not Einstein by RealProgrammer · · Score: 2, Funny

    Leif Ericson discovered it hundreds of years earlier, and the Native Relativians were already there anyway. Their boats were just to slow to test the theory.

    Eurocentric insensitive clods!

    --
    sigs, as if you care.
  5. Depends on How You Look at It by Doc+Ruby · · Score: 3, Interesting

    Although he's a hero of mine, I've found only Einstein's "photoelectric effect" insights to be a work of genius - a "quantum leap", if you will (or even if you won't, how will I know? It's all the same to me...) Relativity is brilliant, and changed science and culture forever. But it's really an ingenious refinement of Maxwell's field equations, even more than extra precision added to Newton's formulas.

    --

    --
    make install -not war

    1. Re:Depends on How You Look at It by wass · · Score: 5, Informative
      Relativity is brilliant, and changed science and culture forever. But it's really an ingenious refinement of Maxwell's field equations, even more than extra precision added to Newton's formulas.

      First of all you're only referring to special relativity here, which ignores acceleration and gravity. Secondly, there were still some leaps of faith to be made, such as assuming c is constant in all frames of reference, which Lorentz showed non-Newtonian transformations that would allow this for Maxwell's equations. And expanding the new energy definition and concluding the zeroth-order term (mc^2) is the rest energy of mass also took another leap of faith (although that paper wasn't published until a few months after this first relativistic one).

      But even so, discovering the connection between relativity and E&M is still amazing, in my opinion. For examle, the permittivity (epsilon_0) and permeability (mu_0) of free space are two constants that can be measured in the laboratory rather easily. Yet Maxwell's equations in vacuum describe waves travelling at speeds 1/sqrt(epsilon_0*mu_0), which is exactly the speed of light in vacuum (although in Gaussian units this connection is far more obvious). It's pretty amazing to think how these are related. But you still need to make some assumptions to get the Lorentz transforms between reference frames.

      Additionally, even simple special relativity was extremely controversial, it rejected many assumed notions of space/time. There were also many paradoxes that took awhile to get ironed out. Many scientists didn't believe in relativity until it was shown in experiment. And in fact the theories of relativity were so controversial that the Nobel committee didn't want to award Einstein the prize based on these, so went for the safer 'Photoelectric Effect' instead.

      And thirdly, general relativity, although again not included in this 100 year anniversary, is total genius, and it took Einstein 10 years to come up with the theory. So don't wave off relativity as just a 'refinement of Maxwell's field equations' because it really is much more than that.

      --

      make world, not war

    2. Re:Depends on How You Look at It by Doc+Ruby · · Score: 2, Insightful

      (BTW, nice .sig ;)

      Well, we are discussing special (not general) relativity. General is a magnum opus. But we might have a merely semantic disagreement, which does reflect in different standards for "genius". I mean it quite literally, "the origin or source". Special relativity was an evolution of Maxell's fields, and General relativity was an evolution of Special. Even the equivalence of gravity and EM was implications of those progressive developments. Often it is a novel implication that is more valuable, and even a greater insight than some other works of genius (like Bell's telephone, mic'ing a telegraph to a speaker). Einstein's relativity was much more than a refinement of Maxwell's field equations, but not a truly original work. Conversely to your perspective, I don't wave off Maxwell's fields - they were a towering work of genius (unless there's a predecessor I don't know about).

      Every great scientist or mathematician I know of stands on the shoulders of giants. I just consider Einstein's Photoelectric Effect to be a leap off those shoulders (as did the Nobel committee), while Relativity was more like tippy-toes.

      --

      --
      make install -not war

    3. Re:Depends on How You Look at It by JRIsidore · · Score: 2, Insightful

      Einstein took it further to postulate that laws of physics ARE the same in all reference frames

      Nope, that was already postulated by Newton. The laws of Newtonian mechanics are the same in all frames of reference and they are transformed by the Galilei-transformations. I guess this was also the drive for Lorentz to look for transformations which do the same on Maxwell's equations.
      What Einstein managed was to bring these two contradictory theories into a consistent one, the Special Relativity.

      </nitpick>

      --
      :w!q
    4. Re:Depends on How You Look at It by xPsi · · Score: 2, Informative
      First of all you're only referring to special relativity here, which ignores acceleration and gravity.

      I agree with the central message in your post. However, SR does include acceleration, jerk (the third derivative of position with time), and in principle all orders of positional change with time. You can also apply gravity as "just another force" in Newton's Second Law F=dp/dt, where F is the net force and dp/dt is the instantaneous rate of change of the momentum in time. Relativistically, p=gamma*m*v where gamma=1/sqrt(1-v^2/c^2). SR is an essentially complete package of kinematics and dynamics just like Newton's Laws. You can do (highly) accurate rocket science with it and certainly don't have to stop with velocity!

      What SR does not develop fully is the "equivalence principle" which says, in brief, that gravitational acceleration and "kinematic" acceleration (e.g. sitting in an accelerating frame) are indistinguishable. When fully developed, this concept intimately links space-time to the gravitational force in a non-trivial way -- and is what makes GR fundamentally different than Newton's Laws and SR.

      --
      i\hbar\dot{\psi}=\hat{H}\psi
    5. Re:Depends on How You Look at It by wass · · Score: 2, Informative
      Einstein basically came up with SR because he was troubled by some apparent (and well known at the time) contradictions between Maxwell's equations and Newtonian time frames. SR was his method of resolving these contradictions.

      Regarding the photoelectric effect, Planck had already proposed the notion of discrete quanta of radiation a few years prior in order to get a consistent statistical-mechanical description of blackbody radiation that wasn't susceptible to the 'ultraviolet catastrophe'. Einstein extended this theory to explain the bizarre frequency-dependence of radiation to get above the work function of the metal. Was this a tippy-toes process or was it standing on the shoulders of giants? In both our opinions, in this case it was a stroke of genius. I also believe SR was a similar stoke of genius.

      --

      make world, not war

    6. Re:Depends on How You Look at It by mbrother · · Score: 2, Informative

      Special relativity only applies in inertial frames (i.e., no acceleration or gravity). General relativity was developed to handle non-inertial frames.

      Don't get confused by the twin paradox and spaceships that have to accelerate. The twin paradox cheats on these issues as usually presented.

      --
      Professor of Astronomy, Author of Spider Star & Star Dragon (Tor)
  6. 100 Years of Special Relativity by Citizen+of+Earth · · Score: 3, Funny

    You'd think it wouldn't be considered quite so Special any more.

  7. Remember though. . . by smooth+wombat · · Score: 4, Informative
    it's only a theory, not a fact. As such I demand that schools teach that it is tiny demons which are causing the effects we are seeing.

    My theory is just as credible as yours since it's only a theory and not a fact.

    Ok, now that that diatribe is over, what's truly interesting is not that what Einstein proposed 100 years ago is still being studied and restudied, it's that one portion of it was recently confirmed. Frame dragging was only confirmed last year.

    Certainly other parts have been verified (relative time for example) but this portion, frame dragging, puts things in a whole new light. We're not just bodies in space. Instead, are bodies are changing the space around us!

    --
    We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
    1. Re:Remember though. . . by bornyesterday · · Score: 2, Funny

      You mean Maxwell's Daemon?

    2. Re:Remember though. . . by Cheeko · · Score: 2, Informative

      Well more accuratly Frame dragging was proposed 97 years ago ;) as a part of General Relativity. As opposed to Special Relativity :)

    3. Re:Remember though. . . by Decaff · · Score: 2, Informative

      it's only a theory, not a fact. As such I demand that schools teach that it is tiny demons which are causing the effects we are seeing.

      My theory is just as credible as yours since it's only a theory and not a fact.

      It is an extremely well tested theory. For example particle accelerators would not work unless it were true.

      Ok, now that that diatribe is over, what's truly interesting is not that what Einstein proposed 100 years ago is still being studied and restudied, it's that one portion of it was recently confirmed. Frame dragging was only confirmed last year.

      You have, of course, confused Special Relativity with General Relativity.

    4. Re:Remember though. . . by exp(pi*sqrt(163)) · · Score: 2, Informative

      Actually, one could argue that frame dragging predates general relativity. Frame dragging grew out of Mach's Principle. Essentially Mach was worrying about relativity pretty early on. Although Einstein asserted that velocity relative to empty space was meaningless, Mach wanted to argue that so was acceleration. The only way he could make sense of it was if acceleration was relative to the distant stars. This is the very first version of frame dragging - that somehow our local coordinate frame follows the mass in the universe. This whole debate eventually found a partial resolution through General Reltivity where frame dragging became explicit and it was clear that moving masses did, at least in some sense, drag spacetime along with them. Even though GR didn't fully resolve Mach's worries, Einstein's development of General Relativity was probably heavily influenced by Mach's thoughts.

      --
      Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
  8. I Wonder What The Next Relativity Theory Will Be by DanielMarkham · · Score: 2, Insightful

    The guiness of Einstein was that he synthesized some more arcane work into some fairly simple equations, continuing to refine what we knew about the universe
    But it's already common knowledge that we don't have a GUT yet, and everything we do have seems very complex and overdone, much the same as it was before E=mc2
    I can't help but wonder if someone will come along in the next decade or so and synthesize these more complex equations into another step forward for mankind. Who knows? Maybe the answer is something like "42"

    Was Worf A Programmer?

  9. Black Mesa here we come by Sir_Eptishous · · Score: 2, Funny

    This is an incredible time to be alive and watching the strides made by physics. Recent developments in the creation of new forms of matter, and the coming experimental fusion reactor in France make the future hopefully brighter for man and mankind.

    Lets hope we don't end up with a "Black Mesa" incident...

    --
    We play the game with the bravery of being out of range
  10. But it's ONLY a "theory" ... by YetAnotherName · · Score: 4, Funny

    ... and being ONLY a "theory," won't be taught in Kansas public schools.

  11. Re:In case of Slashdotting... by aznrocket · · Score: 3, Informative

    Good coverage. For those in the Toronto, Ontario, Canada area, there are events being held @ the UofT. http://www.fields.utoronto.ca/programs/scientific/ 04-05/string-theory/strings2005/ for more info =)

  12. Three cheers for the public domain. by Anonymous Coward · · Score: 4, Insightful

    And just think -- under today's copyright laws of life+70, these papers would still be under copyright until 2025. Wikipedia is able to publish these today because copyright law was more sane a century ago.

    I am sorry, nothing deserves 120 years of copyright protection. I doubt almost anything needs even 28 years. I weep for those who will be looking back 100 years from now.

  13. This is just one third of the World Year by hubie · · Score: 4, Insightful
    The World Year of Physics is celebrating the year that Einstein put out three of his best papers: Special Relativity, brownian motion, and the photoelectric effect. In addition to the importance of relativity, he also confirmed the existence of atoms with the brownian motion paper, and the existence of quantized energy with the photoelectric effect.

    That was one hell of a year. Any one of those would have established his reputation, but all three, and in the same year!!

    1. Re:This is just one third of the World Year by hubie · · Score: 2, Interesting
      There were philosophical differences as well as a head-to-head clash between Newtonian dymanics (little balls bouncing around not caring about which way time was going) and kinetic theory (entropy, the 2nd law, "time's arrow"). You had reductionists and their counterparts. There was a lot of good work on the atomic theory that led to great advances in chemistry and thermodynamics, but remember that no one had ever seen an atom. I think it is a lot like how some people are wary of quarks because though they make a lot of sense in the standard model, they cannot exist by themselves, which leads to a philosophical distinction (are they real if you can't isolate them?).

      A nice writeup is here.

  14. Obligatory Family Guy Quote by everphilski · · Score: 5, Funny

    Einstein is working in a patent office
    Smith: I'd like to patent this. I call it "Smith's Theory of Relativity"
    Einstein browses through Smith's work, nods approvingly and then kills Smith with the overhead window door
    -everphilski-

  15. Re:Obvious oversimplification by A+beautiful+mind · · Score: 3, Funny

    Re:Obvious oversimplification (Score:-1, Redundant)
    by Moderatbastard (808662) on 2005-06-30 17:49 (#12950737)
    About 5 posts saying more or less the same thing within about a 2 minute interval.

    Let the 'redundant' modding and subsequent bitching begin.
    Well said mate, well said!

    See, there you have it!
    --
    It takes a man to suffer ignorance and smile
    Be yourself no matter what they say
  16. The two postulates .. by RedLaggedTeut · · Score: 4, Informative
    Since it seemed to me 5 minutes ago that people where reluctant to answer to this topic, I went to read the intro of Einsteins paper. I found one line that is memorable and that might help you to answer the quiz-question "What are the two postulates of The theory of special relativity?" The answer is in this quote:

    .. the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good. We will raise this conjecture (the purport of which will hereafter be called the "Principle of Relativity") to the status of a, postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body. These two postulates suffice ..

    The thing that needs explaining to me would be "frames of reference". A difference between two frames can be that they are in motion with respect to each other. For example, take a spaceship accelerating to half the speed of light, starting from our resting position. The 2nd postulate explains that the speed of light can be a constant velocity c, both with respect to the frame of the resting observer and the frame(view) of the spaceship. This leads to the question: if you shoot a light ray(velocity c=the speed of light) from the spaceship moving with half= 0.5 c, how come the light ray moves with 1.0 c from the view of both observers, not with 1.5 c from the resting observer?

    As Einstein states, he then proceeds to reconcile the two seemingly paradox postulates by formulating laws of electrodynamics that will work.

    --
    I'm still trying to figure out what people mean by 'social skills' here.
    1. Re:The two postulates .. by lelitsch · · Score: 2, Insightful

      In the simplest possible terms, "frames of reference for which the equations of mechanics hold good" means that both observers can move at different speeds, but that neither one can accelerate or decelerate while the observation is made.

      This is important because you can always tell by mechanical means if you are accelerating, but without a point of reference, you are unable to tell if you are moving at constant speed. (Gravity and circular motions are just accelerations)

    2. Re:The two postulates .. by aug24 · · Score: 2, Informative
      The thing that needs explaining to me would be "frames of reference".

      Let me help: A frame of reference is anywhere from which you can observe anything. Really!

      You sat in a chair is a frame of reference from which you observe the telly which is not moving much relative to you. You in a car moving across the surface of the earth is a FoR from which you observe roadsigns whipping past you at 70mph. You in a space ship is a FoR from which you observe stars and planets zooming past you at half the speed of light. The equations must also work perfectly if your FoR is sat on the planet watching the spaceship whizz past - it is relative).

      The answer to your second question (why not 1.5c) is simply this: that's the way the universe works. The only reason for asking the question is that you are automatically applying Newtonian mechanics to the world, and the equations of NM are in fact simplified versions of Einstein's equations which are jolly good approximations if the relative speed of the observed thing is much less than speed of light (v << c). Thus they work great for monkeys climbing trees, and we have evolved brains that understand those rules (well, Darwin says so).

      Once you look at an object moving relative to you with an appreciable fraction of the speed of light those rules just don't work. Ask God for more info. For once, Darwin doesn't know either ;-)

      J.

      --
      You're only jealous cos the little penguins are talking to me.
    3. Re:The two postulates .. by Decaff · · Score: 2, Informative

      This leads to the question: if you shoot a light ray(velocity c=the speed of light) from the spaceship moving with half= 0.5 c, how come the light ray moves with 1.0 c from the view of both observers, not with 1.5 c from the resting observer?

      Maxwell's equations of electromagnetism predicted that an electromagnetic wave (such as light) would travel through space at a certain speed (c). This light is not travelling relative to any physical medium (such as the hypothetical 'aether'). The speed of light is determined by certain physical properties of space. Those properties of space are the same no matter how fast you are travelling. Therefore, the speed of any light you encounter will appear the same to you no matter how fast you travel.

    4. Re:The two postulates .. by WryCoder · · Score: 2, Informative
      By 'postulate' Einstein means, "Assume that future experimentation will show that light travels at c wrt any inertial observer, and physics is the same for him." So the answer to "...how come the light ray [doesn't move] with 1.5 c from the resting observer" is simply that experiment shows that it doesn't. Yes, that's not what you might expect from experiments throwing rocks from trains, etc.

      But in the case of light, if you can carefully observe what is going on when the moving physicist makes his measurement of c, you will find that he gets the value he does because his clocks are running slow compared to yours.

      The classic thought experiment here is a 'light clock', with light bouncing between two mirrors. What is the path of the light in the moving clock as seen by the stationary observer, and what does that mean to the rate of the moving clock compared to the rate of an identical stationary clock?

  17. On a Related note by bornyesterday · · Score: 2, Funny

    Half of the native residents of West Virginia are filing a lawsuit against the Einstein estate for his use of the phrase "It's all relative" when he was traveling through the state and asked what he thought of the state compared to New Jersey.

  18. Re:I Wonder What The Next Relativity Theory Will B by Black+Parrot · · Score: 2, Insightful


    > The guiness of Einstein was that he synthesized some more arcane work into some fairly simple equations, continuing to refine what we knew about the universe [...] I can't help but wonder if someone will come along in the next decade or so and synthesize these more complex equations into another step forward for mankind.

    I'm sure more guiness will help.

    > But it's already common knowledge that we don't have a GUT yet, and everything we do have seems very complex and overdone, much the same as it was before E=mc2

    FYI, Einstein didn't make things simpler; he made them more accurate.

    If the universe is complex and overdone, we'll just have to live with complex and overdone theories.

    --
    Sheesh, evil *and* a jerk. -- Jade
  19. audio captures of lectures on special relativity by _peter · · Score: 2, Interesting


    I guess today is the day to finally listen to these...

    http://www.teach12.com/ttc/EinsteinLectures.asp?ai =18990

  20. Re:5th paper by hubie · · Score: 2, Informative

    This says it better than I can.

  21. Moving backwards by ggambett · · Score: 3, Insightful

    100 years ago Einstein was publishing his theory. Today we're discussing intelligent design and how the dinosaurs attacked Noah's ark. Why do I feel we're going backwards? (low res images because of Slashdotting, I guess... can't find a high res version)

    --
    My website
    1. Re:Moving backwards by exp(pi*sqrt(163)) · · Score: 2, Insightful
      Today we're...
      When you say we you use a pronoun that includes me. So that's me you're talking about there. I'm not discussing how dinosaurs attacked the ark. So you're offending me buddy. Watch what you're saying. You really mean "Today there's this crackpot talking about how dinsoaur's attacked the Ark...". And you see, when you phrase it correctly, it has nothing to do with Einstein but is just a statement about a crackpot. Crackpots existed in Einstein's time too.
      --
      Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
  22. Oh great, frame dragging by wsanders · · Score: 2, Funny

    OK, I just heard about this, it's bad enough that I have to drag around a separate PDA, phone, and laptop - now I find out I'm dragging space and time around with me as well?

    --
    Give a man a fish and you have fed him for today. Teach a man to fish, and he'll say "WHERE'S MY FISH, YOU IDIOT?"
  23. Re:Einstein's centenary - big in the UK by rumblin'rabbit · · Score: 4, Insightful
    Einstein fled Germany in 1933 when fascism and anti-semitism become intolerable. Indeed, Einstein may have died in a concentration camp had he stayed. Thus Germany's handling of one of the great scientists of all time is not a proud one.

    Perhaps that is why they are hesitant. Brings up bad memories.

  24. Politicization of science by October_30th · · Score: 2, Insightful
    Yes, I think you could include stuff like ID and Noah's ark under a general phenomenon of anti-science but it's really nothing new. There has always been plenty of anti-science nuts around and they are, well... mostly harmless. As long as no-one tampers with the scientific method, it's ok.

    What's more worrying is the increasingly extensive politicization of science (yes, it's always been political but it's getting even more so), the concomitant drop in the general education levels and the rise of anti-science as a source of feasible political capital.

    --
    The owls are not what they seem
  25. Gravity Probe B by mknewman · · Score: 3, Interesting

    It's worthy of note that one of the more obscure aspects of Einstein's theorum of Relativity is Frame Dragging, which predicts that time and space will be dragged around a spinning object's mass. This is being tested to an extremely high level of accuracy by the 4 most perfect spheres ever created in the Gravity Probe B (http://www.gravityprobeb.com/ experiment going on currently. The project is a 1 year flight with NASA and Stanford as the sponsors, and they are keeping mum as to interim results of the test. Supposedly the results will be announced in the near future after the 1 year test period is complete.

  26. Sci-fi fans would do well to consider this... by Chowser · · Score: 2, Interesting

    If only the fans of sci-fi would learn about special relativity, they would quickly learn that their dreams of intergalactic travel would quickly shrivel up. Consider the so-called "twin paradox" that would have a space traveler age quite differently than the people left behind. Here is a link http://theory.uwinnipeg.ca/mod_tech/node141.html with a brief explanation. Better ones can probably be found.

    --
    sig here
    1. Re:Sci-fi fans would do well to consider this... by Mant · · Score: 2, Informative

      What are you talking about? Sci-Fi with integalactic travel almost never (never in my experience, but I'm sure there are some) has ships that go faster than light by just accelerating conventionally. They usually have some explanation for how they get around relativity (wormholes, shifting to diminsions with different rules etc).

      It's rarely good science, but almost all Sci-Fi authors and fans do know about it.

  27. Re:I Wonder What The Next Relativity Theory Will B by ZombieWomble · · Score: 2, Interesting

    In a way, he did make things simpler too - most of the transformations arising from SR had already beeen derived elsewhere (e.g. when trying to explain the Michleson-Mosley experiment), but Einstein produced a simple rule (i.e. that physical constants are invariant) which led directly to those results - and several other interesting ones, too

  28. Re:Why we all thought of Time dilation immediately by Foobar+of+Borg · · Score: 2, Interesting
    Anyway, it's been nearly 150 years since Darwin proposed his theories - still the debate continues. At least in physics there seems to be less religion messing up with it.

    Well, this is because the fundamentalist wackos don't understand it at all. They don't understand evolution either, but they at least have a BS version of it to bash. Although, I have seen a few fundies mention that the theory of relativity is "only a theory" whereas the laws of thermodynamics are "laws" and thus somehow help their arguments. Basically, it is another "argument by semantics".

    Crazy, crazy people...

    --
    Similar to the upcoming US election results
  29. Re:Why we all thought of Time dilation immediately by brainstyle · · Score: 2, Interesting
    Anyway, it's been nearly 150 years since Darwin proposed his theories - still the debate continues. At least in physics there seems to be less religion messing up with it.

    Alas, that isn't the case.

    --
    "Why can't everyone just be straight with me?"
    "Because we live in a bendy world, dear."
  30. Re:Relativity has no basis to begin with by ZombieWomble · · Score: 2, Informative
    Your 'proof' boils down to the following line:

    "This indicates that according to the Lorentz transformation, nothing can have the same speed relative to both K and K' unless it is a ray of light"

    You then calmly assert that this is nonsense and claim certain mathematical assumptions are to blame. However, even a moment's thought about this indicates that this makes perfect sense - The two frames are in relative motion to one another, and thus for any object the observed velocity would be V = Vframe+Vobject (or it's relativistic correction, for high velocities). So, unless both frames have the same Vframe (i.e they are the same frame), nothing but two rays of light can have the same velocity in both frames - as in the postulates of special relativity.

    In effect, you have proved that Lorentz transformations are the ones which are consistent with SR.

  31. galileo first stated relativity by peter303 · · Score: 2, Interesting

    "Any two observers moving at constant speed and direction with respect to one another will obtain the same results for all mechanical experiments."

    Galileo was trying to explain why its difficult to tell the earth is moving: when everything moves in unison its like relatively no motion at all. Thats why we dont have thousand mile winds at the equation, the soup doesnt pool to the east in its bowl, etc. The other image Galileo used was things and activities inside a moving ship.

    Einstein amplified this to objects moving rapidly to one another with the assumption there is a maximum constant velocity.

  32. BBC radio stories to mark the centenary by Forget4it · · Score: 3, Informative

    Theories of Relativity
    Five specially commissioned short stories to mark the centenary of Einstein's discovery. Listen to them for next few days only here .
    Share and Enjoy!




    --
    Artificial intelligence is the study of how to make real computers act like the ones in the movies.
  33. Re:Maybe you can explain something to me... by lgw · · Score: 2, Informative

    There is no relavistic mass effect!!!

    This is an oversimplification to the point of becoming myth - and the numbers don't even work out.

    f = ma

    The oversimplification is to suggest that if F produces less acceleration than expected, mass must be growing, but that's BS, because:

    KE = (mv^2)/2

    The relavistic correction for kinetic energy is the square of the correction for acceleration, *not* the same correction. Mass isn't changing at all, time is. Put Newton's law in the form Newton did, and this becomes ore clear:

    f = d(mv)/dt

    If your clock is moving slower (from an observer's point of view) then the same force produces less change in momentum, because that force is acting for less time.

    No imaginary extra mass needed! Your *momentum* effectively increases, but that's *not* because your mass gets larger, it's because your time slows down, so it takes longer for a given force to affect you by to a given degree. All from a stationary observer's point of view, of course: from your point of view nothing has changed, and it's *their* clocks that have slowed!

    --
    Socialism: a lie told by totalitarians and believed by fools.
  34. Re:Maybe you can explain something to me... by ZombieWomble · · Score: 2, Informative
    There is a relativistic mass effect, if you want there to be. It's not necessary, and in many formulations is counterintuitive, but it can be used in a number of formulations to keep things straight - e.g. its use means that E=mc^2 always holds true, not just for rest states.

    Even in the example you cited, relativistic mass still has a place. Specifically, if we choose not to use relativistic mass, we can no longer simply express momentum as mv, because using the rest mass and speed measured from the rest frame, we would obtain incorrect results, since as you say the momentum has effectively increased.

    While you're right to say that there is no 'extra mass', it is true to say that the energy of a body affects its inertia (See Einstein's 4th 1905 paper, I believe), which can be expressed as a modified mass term, if we so desire.

  35. Original Papers Online: Annalen der Physik by AtomicJake · · Score: 2, Informative

    All five articles from Einstein (and many more important articles since 1799) have been published in the Annalen der Physik, the leading scientific journal at that time.

    Thanks to the French digital national library Gallica, you can now access ALL (or nearly all) pages of the Annalen der Physik: on-line and from 1799 - 1930.

    Obviously: to understand this publication, it helps a lot to read German, the former lingua franca of the science.