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Science

E ~ mc^2 510

Posted by michael from the close-only-counts-in-horseshoes dept.
DrBlake writes "New York Times has an article about a study of Einsteins theory of relativity that I found very interesting. Not only might the speed of light be relative under certain circumstances, the famous equation E=mc2 might not be entirely correct."
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E ~ mc^2 More

E ~ mc^2

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  • Oh no.... (Score:3, Funny)

    by t3kad0n ( 636763 ) on Wednesday January 01, 2003 @02:00AM (#4992544)
    My world is falling apart.
  • Just A good idea. Not the law. ?
    • I see this story and then look down at the bottom of the page. Lo and behold, the QOTD has special meaning in this context:

      186,000 Miles per Second. It's not just a good idea. IT'S THE LAW.

  • The more we learn (Score:2, Insightful)

    by cbensinger ( 127227 )
    the less it seems that we know. I'm not a scientist by any stretch of the imagination; but considering how much of our science is based on this kind of thing I do find it amazing that that at this point in time we're now questioning the e=mc^2....

    • You misunderstand completely (Score:4, Insightful)

      by kfg ( 145172 ) on Wednesday January 01, 2003 @02:39AM (#4992695)
      The more we learn where our knowledge is incorrect the more *correct* it becomes. The job of the scientist is thus to question *everything.*

      The very thing that shakes your faith in our knowledge is the very thing that *strengthens* our knowledge.

      Think about it.

      KFG

      • Re:You misunderstand completely (Score:5, Funny)

        by Hektor_Troy ( 262592 ) on Wednesday January 01, 2003 @07:58AM (#4993232)
        The job of the scientist is thus to question *everything.*
        Why?
    • Comment removed based on user account deletion
    • This quote says it all:

      We don't replace a theory with one that is better. We replace it with one that is slightly less wrong.
      -- Prof. Stephen Hawking

  • Even if he was off.. (Score:4, Insightful)

    by OmniVector ( 569062 ) <see my homepage> on Wednesday January 01, 2003 @02:03AM (#4992560) Homepage
    It still answered some questions and anomolies about the universe and changed the way we think about the world.

  • Light Speed Relative? (Score:2, Insightful)

    by cranos ( 592602 )
    I thought this was obviouse. If a blackhole can suck light into it then it will be affecting the speed at which it travels, all celestial bodies will, its just the magnitude that differs.

    • Re:Light Speed Relative? (Score:4, Informative)

      by Jordy ( 440 ) <.moc.pacons. .ta. .nadroj.> on Wednesday January 01, 2003 @02:43AM (#4992699) Homepage
      A blackhole warps space and time around it. Light travels in a straight line, but since the space it is traveling over is warped, it enters the black hole.

      The light itself does not speed up or slow down. From outside the blackhole, light is moving away from an observer at the speed of light. From inside the blackhole, light is moving towards you at the speed of light.

      You have to remember that "speed" is a function of distance and time. Time is not constant, but from any frame of reference (you for instance) however, the "speed" of light is.
    • wtf?

      blackhole's don't "suck" anything in. anything with a gravitational field "bends" light, or acts like as a lens because light has mass.

      light traveling at c across the void of space and light orbiting a super-dense mass at c are still both moving at c. it's just that the latter will never leave the "event horizon" of the black hole. still the same speed.

      justin dubs

    • I'm sorry, but this is entirely incorrect. (Score:4, Informative)

      by kfg ( 145172 ) on Wednesday January 01, 2003 @02:50AM (#4992719)
      The fact that light is in orbit has *no* effect on its speed. You're thinking of light as a Newtonian object getting "sucked into" the black hole. Light isn't "sucked in." The escape velocity of the black hole is simply higher than the speed of light and the light follows a ballistic trajectory. . . at * the speed of light.*

      Light is not Newtonian. It dosn't "speed up" as it falls, or "slow down" as it rises. That's kind of the point. Try working some simple Lorentz Transformations to begin to get a feel for this.

      KFG

      • Dude. I have to say it. I *have* to say it.

        Lorentz transformations might be "normal math" to you, but to a lot of people (even the average slashdotter) they probably aren't. Think about it. If the poster that you're replying to could *do* Lorentz transformations then he wouldn't be having this mental roadblock...because by learning how to do them, he would have figured out the concepts involved.

        It might be more helpful in the future to say something like "here is a cool little Java applet that visually (and interactively) explains a Lorentz transformation [qmul.ac.uk]. It's not a thorough mathematical explanation, but it should give you some clues to what I'm talking about. Simple Lorentz transformations can be done easily with the skills that you (hopefully) learned in high school algebra. I know that most papers explaining Lorentz transformation are written in mathematicese, but, hey, it's just like learning Perl. Take it slowly, one step at a time, and work all of the examples out yourself. Good luck."

  • Granted I am not a physics expert, but isn't this pretty old news? There have been good theories around for a long while that require either ammendments or nullification of Einstein's E=MC^2 to exist.

  • E=M*c^2 story. (Score:4, Informative)

    by Anonymous Coward on Wednesday January 01, 2003 @02:06AM (#4992570)
    The New York Times Sponsored by Starbucks
    December 31, 2002
    E and mc2: Equality, It Seems, Is Relative
    By DENNIS OVERBYE

    Roll over, Einstein.

    In science, no truth is forever, not even perhaps Einstein's theory of relativity, the pillar of modernity that gave us E=mc2.

    As propounded by Einstein as an audaciously confident young patent clerk in 1905, relativity declares that the laws of physics, and in particular the speed of light -- 186,000 miles per second -- are the same no matter where you are or how fast you are moving.

    Generations of students and philosophers have struggled with the paradoxical consequences of Einstein's deceptively simple notion, which underlies all of modern physics and technology, wrestling with clocks that speed up and slow down, yardsticks that contract and expand and bad jokes using the word "relative."

    Guided by ambiguous signals from the heavens, and by the beauty of their equations, a few brave -- or perhaps foolhardy -- physicists now say that relativity may have limits and will someday have to be revised.

    Some suggest, for example, the rate of the passage of time could depend on a clock's orientation in space, an effect that physicists hope to test on the space station. Or the speed of a light wave could depend slightly on its color, an effect, astronomers say, that could be detected by future observations of gamma ray bursters, enormous explosions on the far side of the universe.

    "What makes this worth talking about is the possibility of near-term experimental implications," said Dr. Lee Smolin, a gravitational theorist at the Perimeter Institute for Theoretical Physics in Ontario.

    Any hint of breakage of relativity, scientists say, could yield a clue to finding the holy grail of contemporary physics -- a "theory of everything" that would marry Einstein's general theory of relativity, which describes how gravity shapes the universe, to quantum mechanics, the strange rules that govern energy and matter on subatomic scales.

    Even Einstein was stumped by this so-called quantum gravity.

    For now, any clue would be welcome. There is very little agreement and much confusion about the possible end of relativity. "These are times when theorists are being very adventurous," said Dr. Andreas Albrecht, a physicist at the University of California at Davis. "It's hard to tell where things will go."

    The avatars of new relativity have been encouraged by hints that some cosmic rays hitting Earth from outer space have more energy than normal physics can explain. But some scientists doubt that these rays exist or, if they do, that a violation of relativity is the only way to explain them.

    The cosmic ray hints are not the only signs making physicists wonder about relativity. They have also been tantalized by evidence, as yet unconfirmed, from distant quasars that a fundamental constant of nature, a measure of the strength of electromagnetism known as the fine-structure constant, might have changed ever so slightly over billions of years, shifting the wavelengths of light emitted by the quasars.

    The result has been a minor explosion of interest in strange relativity, with some 70 papers being published this year, said Dr. Giovanni Amelino-Camelia, a theorist at the University of Rome.

    The field, while still small, is destined for at least 15 minutes of fame next year with the publication in February of "Faster Than the Speed of Light," by Dr. João Magueijo, a cosmologist at Imperial College London. The book is a racy account of Dr. Magueijo's seemingly heretical effort to modify relativity so that the speed of light is not constant, and he will promote it on a long lecture tour.

    "Ruling out special relativity by 2005 is a bit extreme," Dr. Magueijo said in a recent e-mail message, referring to the coming centennial of Einstein's famous paper, "although I would be very surprised if by 2050 nothing beyond relativity has been found."

    Most physicists have yet to buy into this presumed revolution. Dr. Edward Witten of the Institute for Advanced Study in Princeton, called recent arguments that some versions of quantum gravity would violate relativity "unimpressive."

    Dr. Juan Maldacena of Harvard said he doubted relativity was violated in string theory -- the leading candidate for a theory of everything. "But of course," he noted, "we should always test our theories."

    Dr. Carlo Rovelli, a gravitational theorist at the University of the Mediterranean in Marseille, said it was a "risky" hypothesis, "but the prize if it happened to be true is so great that it is worthwhile taking the risk of exploring it in detail."

    Dr. Andrew Strominger of Harvard pointed out that Einstein himself modified relativity in 1915, when he brought gravity into the picture with his general theory of relativity. Special relativity, as the 1905 theory became known, is only strictly valid in flat space without gravity, Dr. Strominger said.

    He added, "It is natural to think that Einstein's relativity will in some sense be violated by small corrections, just as Newton's theory of gravity has small corrections." These corrections did not make Newton wrong, he said, they just meant his theory was not always perfectly applicable. Likewise, relativity may give way to a more complete and accurate theory.

    How relativity could break down, if it does, depends on how physics might accomplish its grand dream of quantum gravity.

    Many physicists are placing their bets on string theory's mathematically imposing edifice in which nature comprises tiny strings vibrating in 10 dimensions of space-time. But this theory may play out in billions of ways, and some physicists complain that it can be made to predict almost anything.

    In the late 1980's, Dr. V. Alan Kostelecky, a particle physicist at Indiana University, and his colleagues pointed out that in some of these solutions, the spins of the strings could impart an orientation to empty space, like the lines left by the weave in a fine cloth. In that case, they say, a clock oriented in one direction could tick slightly faster or slower than one oriented differently, in violation of the rules of relativity. That is something Dr. Kostelecky and his colleagues have proposed to test using ultraprecise clocks on the space station.

    Dr. Kostelecky and his colleagues have constructed an extension to the standard model of particle physics that catalogs all the possible ways that relativity can be violated. Others, including Dr. Amelino-Camelia, Dr. John Ellis of CERN, Dr. Tsvi Piran of the Hebrew University in Jerusalem and the Harvard theorists Dr. Sheldon Glashow and Dr. Sidney Coleman, have attempted to study the ways that relativity can be violated by quantum gravity or in the high-energy cosmic rays.

    Violation is not inevitable, Dr. Kostelecky said. "Is it plausible? Yes. Is it likely? Enough so that I've invested years of my life."

    Few physicists would seem to have as much invested in revising relativity as Dr. Magueijo. In his book he describes how beginning in 1996 he cajoled Dr. Albrecht, then at Imperial, into pursuing with him the heretical notion that the speed of light had been much higher in the dim cosmic past as a solution to various cosmological puzzles. Cosmologists did not rally to the idea, which even Dr. Magueijo admitted violated relativity. His co-author, Dr. Albrecht, himself called it an idea that is "not even properly born yet," and said it needed to find roots "in some convincing physics."

    In the intervening years, as a sideline to his day job as a conventional cosmologist, he and a growing number of comrades have continued to tinker with modifying relativity in a variety of ways that go under the umbrella name of V.S.L., for variable speed of light theories.

    In the science world, the book might attract attention for its jaunty and irreverent style as well as for its content. "What the hell, it's only Einstein going out of the window . . .," he writes in one passage. In others he describes the editor at a prominent journal as a moron, his bosses at Imperial as pimps and the rival quantum gravity camps as cults.

    Asked how he expected his colleagues to react to the book, he answered, "It wasn't written for them; it was written for the public." He called it "a very honest view of how scientists feel," adding, "It's the language I use normally."

    The main motivation for considering V.S.L. theories, Dr. Magueijo explained, comes from the as-yet undiscovered quantum gravity. In relativity there is only one special number, the speed of light, but in quantum gravity, he explained, there is another special number, known as the Planck energy, equivalent to 1019 billion electron volts. According to quantum gravity thinking, an elementary particle accelerated to that energy will behave as if space and time themselves are lumpy and discontinuous and all the forces of nature are unified.

    According to relativity, however, Dr. Magueijo explained, differently moving observers could disagree on how much energy the particle had and thus whether it was displaying quantum gravity effects or not. In short, they would disagree on what the laws of physics were.

    "Perhaps relativity is too restrictive for what we need in quantum gravity," Dr. Magueijo said. "We need to drop a postulate, perhaps the constancy of the speed of light."

    The most recent buzz in V.S.L. circles is about something called "doubly special relativity." In 2000, hoping to fix the cosmic ray problem, Dr. Amelino-Camelia proposed modifying the rules of relativity so that there would be a limit to the momentum that any particle could have, just as now there is a limit to the velocity.

    Subsequently Dr. Magueijo and Dr. Smolin of the Perimeter Institute proposed their own doubly special version in which there is a limit to the amount of energy that an elementary particle can attain, namely the so-called Planck energy, at which the forces are unified and quantum gravity effects dominate.

    One casualty of this tinkering, the V.S.L. scientists agree, will be everyone's favorite formula, E=mc2, to be replaced by a more complicated, cumbersome equation that Dr. Magueijo reproduces in his book.

    A mark of all the doubly special theories, Dr. Magueijo said, is that the speed of light will vary with its color, with higher frequencies and energies going slightly faster than lower ones. That might manifest itself in observations of gamma ray bursters, distant gargantuan outbursts by an upcoming NASA satellite called Glast (gamma ray large area space telescope), scheduled for launching in 2006.

    The theory also predicts that light should slow down near massive objects and actually come to a stop at the end of a black hole, preventing anything from entering that dark gate, Dr. Magueijo said in his book. In principle the effect, he said, could be tested by spectroscopic measurements of the light emitted from dense objects like neutron stars.

    To some physicists, however, the very idea of variations in the speed of light in a vacuum -- the c in E=mc2 -- is meaningless. The miles and seconds by which speed is measured are human inventions, they point out, defined in fact in terms of lightwaves, so the whole notion of the speed of light varying is circular. In the last analysis, they point out, all physical measurements boil down to a few dimensionless constants like the fine structure constant, alpha. "What we measure objectively is whether alpha varies," said Dr. Michael Duff of the University of Michigan in an e-mail message.

    Dr. Magueijo said those criticisms were technically correct but said the speed of light was one factor of several in the formula for alpha. So if alpha varied, as some astronomical measurements have suggested, one could choose to think of it as a variation in the speed of light, of electric charge, or even a variation in another number known as Planck's constant -- or all three -- if that made the math simpler. "It's a matter of convention," he said, adding, "you make the simplest choice."

    Despite all the activity, scientists agree that they are mostly in the dark about the deeper consequences of these conjectures. "Some may eventually be developed to the point of being a credible alternative to relativity," conceded Dr. Kostelecky, saying that he suspected that others might not really change relativity or might have already been excluded by existing experiments. Without a systematic analysis it was impossible to know.

    Dr. Amelino-Camelia said that the doubly special theories preserve Einstein's principle that all motion is relative, but at an unknown cost to the rest of physics."We paid a dramatic price for relativity: the notion of absolute time," he said. "This time it is not completely sure what is the axiomatic principle we have to give up."

    Dr. Albrecht urged caution and said physicists needed guidance from experiments before tossing out beloved principles like relativity. "The most dignified way forward," he said, "is to be forced kicking and screaming to toss them out."

    Copyright 2002 The New York Times Company | Permissions | Privacy Policy

  • Of course not.... (Score:2, Informative)

    by starsong ( 624646 )
    It's (E^2) = (m^2)(c^4) + (p^2)(c^2).

    Unless everything in the universe has zero momentum, that is. :)

    • Re: (Score:3, Informative)

      by account_deleted ( 4530225 )
      Comment removed based on user account deletion
    • >> It's (E^2) = (m^2)(c^4) + (p^2)(c^2).

      Actually, it's E = m * c^2, where m is the rest mass times the Lorenz transform.

      If you then subtract the rest energy from the energy when in motion (m*c^2 - m0*c^2), you get the kinetic energy, which at low speeds is approximately equal to 1/2*m*v^2, which we all recognize as the formula for kinetic energy in Newtonian physics.

      That is to say, relativistic kinetic energy is not exactly equal to newtonian kinetic energy.

  • No = Registration*link^2 (Score:5, Informative)

    by Anonymous Coward on Wednesday January 01, 2003 @02:06AM (#4992576)
    NYT article [nytimes.com]

  • can someone explain to me (Score:3, Interesting)

    by SHEENmaster ( 581283 ) <travis@uUUUtk.edu minus threevowels> on Wednesday January 01, 2003 @02:11AM (#4992587) Homepage Journal
    What c is relative to? When we say that a car is moving at 60mph we meann relative to the ground, but what is c relative to?

    If it's relative to a "given thing" then doesn't that hint toward Ether theory? The further we go in AP Physics the more I realise that my school is imprepared to answer anything that comes up and that modern theories (String theory and the like) seem reminescant of the old ones like Ether theory.

    • That's the paradox... (Score:5, Informative)

      by starsong ( 624646 ) on Wednesday January 01, 2003 @02:17AM (#4992609)
      ...and the beauty of special relativity.

      They key thing is that the speed of light is fixed relative to *everything*. This means that if I'm standing by the highway and measure it, I get the same speed as a person in a car going 60 mph away from me. And since the speed of light is fixed, everything ELSE distorts to make up for it. That includes time (time dilation) and space (Lorentz contraction). It leads to some pretty freaky and amazing consequences.

      • Re:That's the paradox... (Score:5, Informative)

        by Trogre ( 513942 ) on Wednesday January 01, 2003 @07:05AM (#4993169) Homepage
        A good way to observe (well, simulate) some of these effects is to download lightspeed [sourceforge.net] and have a play. Effects such as Lorentz contraction, doppler shift, headlight effects and optical aberrations can be observed. Very cool with the add-on Starship Voyager model.

        There's also some very nice mpegs floating around the net of tram cars and flashing lamp posts in a world where the speed of light is slowed to a couple of meters per second. Now if only I could dig up the URL...

    • No, no, c is relitive to anything. That is the magic of the math of special relitivity. No matter what refrence frame you look at something moving at the speed of light, it is still moving at the speed of light. Distance and time are physicly warped to inforce this speed limit. It sounds crazy but its true. There is no ether.

    • Re:can someone explain to me (Score:5, Interesting)

      by rossifer ( 581396 ) on Wednesday January 01, 2003 @02:37AM (#4992688) Journal
      c is relative to the observer, no matter which observer we're talking about. Anything that can measure the speed of a photon will always measure it going at the speed of light through that substance. Through a perfect vacuum, it's c. Through space it's c - epsilon (epsilon is an infintesimally small number). Through water it's about c/1.335.

      If you are zooming past me at half the speed of light and both of us measure the speed of a particular photon at the same time, we'll both measure it's speed as c. What will be different about our two measurements is that you'll see a higher energy photon (bluer) than me if the photon is moving opposite to your motion relative to me and a lower energy photon (redder) if the photon is moving in the same direction as your motion relative to me.

      No particular point in space is special. Once you identify where the observer is located, you can call that point in space an "origin" or "zero" and make all of your measurements from that point in space. The rest of the universe relative to that origin is called an "inertial reference frame", but it's just the same as any other reference frame. There's another trick. Behavior of things in inertial reference frames is time dependent because gravity pulls your frame around and changes everything around it slightly every moment. Besides that, two inertial reference frames may have a relative velocity but for a moment share the same point in space (the example above).

      That's when tensor math starts to come in handy. Don't worry, I won't torture you with that.

      Relativity, once you grok it, will bend your mind. From a metaphysical perspective, it emphasizes the reality that most of what we call facts are actually just high probability observations.

      Remember, there is no spoon.

      Regards,
      Ross
      • That's when tensor math starts to come in handy. Don't worry, I won't torture you with that.

        I've heard the same damn "Just Because" explanations forever! I downloaded a quite lengthy explanation of Tensor Calculus to my Zaurus.

        What I was really asking is if anyone knew the basis for these theories.

        • Re:PLEASE torture me with that! (Score:4, Informative)

          by Aleatoric ( 10021 ) on Wednesday January 01, 2003 @02:58AM (#4992742)
          I'll let someone else torture you with tensors :o)

          Here are three (of many) links that I've found in the past that deal with relativity and provide varying degrees of rigor and completeness in the explanations.

          How stuff works! Talking about special relativity:
          http://www.howstuffworks.com/relativi ty.htm

          A pretty interesting and more rigorous explanation:
          http://physics.syr.edu/courses/modul es/LIGHTCONE/

          And finally, a question and answer format explanation :o)
          http://www.sciencenet.org.uk/database/Physics /List s/relativity.html

          This should get you a good set of basic coverage about relativity.
        • What I was really asking is if anyone knew the basis for these theories.

          Ah. I'm not going to be able to do more than point you in the right direction in one /. posting. For that direction: don't worry about tensor math yet, you won't need it until Special Relativity. In the short term, you should study a good "Modern Physics" text. Specifically, Maxwell's equations, the theoretical underpinnings of each equation and finally, their application to EM fields.

          At that point, there's enough information to head over to the General Relativity chapter and take a gander. That ought to be enough to blow your mind for a little while as what you thought you knew about the universe resorts itself (don't worry, it happens to almost everyone).

          After that, you can finish the book, develop some basic tensor math skills, then come back and explain Special Relativity to all of us! Actually, I do get Special Relativity, but it is mind bending. You really start thinking about the universe on a completely different scale.

          I found it incredibly interesting stuff to learn, but because I went to a non-top-twenty school, there were only a few other people in my class with any interest. The hostility from the other undergrad students who hated learning (and especially hated having to rethink the universe) was a bit of a downer for the in-class exchange that the prof was so hoping for.

          The graduate level classes were much more fun. :)

          Regards,
          Ross

    • Re:can someone explain to me (Score:5, Insightful)

      by GMFTatsujin ( 239569 ) on Wednesday January 01, 2003 @03:00AM (#4992744) Homepage
      Lordy... You don't ask much, do you?

      The speed of light is constant in all possible frames of reference, according to Einstein. Basically what he's saying is that for any two objects at rest relative to each other (regardless of their motion to the rest of the universe, they appear not to be moving to *each other*), time and space behave in the same way. The beauty of his theory is that no one object can be said to be at universal rest to everything else -- there is no universal frame to measure against. Therefore, every frame of reference is valid and will behave the same way. This kills Ether theory dead, since Ether theory depends on a universal frame of reference. If it didn't have a universal frame of reference, then space and time would start behaving oddly within your *own* frame of reference depending on your motion. This is not the case - the light on Pluto behaves the same way as the light on Earth, even though the two are moving in different frames.

      It's only when you introduce out-of-frame references (I'm standing still, the train is moving at 60mph away from me) that relativity kicks in and the laws start to behave weirdly.

      Not inconsistantly, just weirdly. It's all in shifting your viewpoint.

      The trick with light is to realize that although it travels at the same speed in every frame of reference, the *wavelength* is what changes between frame. This is what that whole red-shifting/Doppler effect is about. The speed of light is constant; the color, however, changes depnding on your frame of reference. If you shoot a blue light at me while we're both standing still relative to each other, it looks blue to me. If I run away *really fast*, it will still be blue to you, but it will appear red to me because the wavelength alters even though it still travels toward me at a constant rate. Ditto if *you* run away from me - the light is blue to you, but again, it appears red to me, even though it travels at the same speed.

      Light does not behave in the Newtonian way - acceleration does not effect its speed, only its wavelength. That's where the question of why light is constant to everything, even moving objects, is answered.

      Weird, huh?

      For a far, far, better explanation (and a fantastic grounding on String Theory in terms for non-physicists) check out The Elegant Universe [amazon.com] by Brian Greene. If I could, I'd give this book a Pulitzer every year until the day I died.
      • So its wavelength is not an indication of speed as it is with every other type of wave?

        So with light, velocity!=wavelength*frequency?
        • Comment removed based on user account deletion

        • Re:only its wavelength? (Score:3, Informative)

          by Alsee ( 515537 )
          So with light, velocity!=wavelength*frequency?

          For light velocity DOES wavelength*frequency.

          But different people will see the same photon as having different wavelenths and different frequencies. When you travel very fast you get time dilation and time slows down for you. When your clock runs slow more "waves" will occure in one second. The frequency appears to increase. High speed also cause distortions in apparent distances.

          EVERYONE will see the volocity as C. It doesn't matter if you are standing still or moving towards the light at 500 million miles per hour or moving away from the light at 500 million miles per hour. The light always looks to you like it is moving at speed C.

          -
    • String Theory doesn't touch Ether with a ten-foot pole.

      String Theory, in part, seeks to explain the structure of the universe in such a way as to accomodate both gravitation and quantum effects. It does this by shifting the understanding of particles from a family of points that all have different properties (protons, electrons, quarks, what have you) toward a *truly* fundamental form of matter - a string - that displays different properties depending on its orientation and motion in space. One (and ONLY one) type of string, many configurations, all leading up to families of particles.

      It's elegant, unproven, pretty damn keen, and possibly wrong, but worth a look. The math involved makes *predictions* about the fundamental properties of matter, rather than being built off of measurements of those properties (as quantum theory and relativity are). That's an important step that cannot be underscored enough.

      String Theory doesn't posit that there's a universal medium that everything travels through, as Ether theory does. Instead, it describes a configuration of space that strings wiggle around in to produce the world that we're used to looking at.

      String Theory rocks. I hope it's right.
      GMFTatsujin
      • The math involved makes *predictions* about the fundamental properties of matter

        Yeah, except we have basicly zero clue what the predictions are. Pretty interesting definition of "prediction" :D

        -

        • That's not exactly true... (Score:4, Informative)

          by jpmorgan ( 517966 ) on Wednesday January 01, 2003 @04:22AM (#4992877) Homepage
          It's not exactly true that we have no clue what string theory's predictions are.

          On one hand, the formulations of string theory are Very Hard (TM). I'm sure you think youv'e seen hard math, but there's hard math and there's string theory math. Classic standard model quantum mechanics and general relativity is hard math, nice hard partial differential equations to solve. String theory math makes this look easy though. It's so hard that nobody has yet even formulated the exact equations - everybody's working with approximations. So the predictions that people are making with string theory may not be completely accurate, as they aren't working from the real threory, just an approximation of it. Nice, eh?

          On the other hand, most of the quantitative predictions that string theory does generate are mindboggling hard to test anyway, since in almost all respects string theory agrees with classic quantum mechanics (there's an oxymoron...) until you get to some pretty insane energies (think plank energy).

          Fortunately, recently a few physicists have come up with some more subtle qualitative predictions that should prove feasible to test (for example, string theory predicts that cosmic microwave background radiation should be pixelated - the big bang didn't do antialiasing:).

    • I hate to say this... (Score:4, Funny)

      by dasunt ( 249686 ) on Wednesday January 01, 2003 @04:15AM (#4992871)

      But why do you think that your brain is capable of understanding the basic forces of the universe?

      Your brain evolved to keep you away from things that want to eat you, find things you want to eat, and basically preserve you until you could insure that you have spread your genes. Last time I checked, understanding the basic rules of reality wasn't needed to ensure that you live long enough to breed.

      Hell, we'er just lucky that the same math that works on our scale also seems to work when we look at how the universe works.

      Even now, logic has begun to fail us when we ask the deep questions. Consider this: What made this reality? Oh sure, I know the theories that suggest that this universe might have been created by another universe, and at this level, cause and effect goes out the window, leading to the possibility that this universe can create the ancestor of the universe that created it, but what allowed this gestalt to exist?

      There's an Heinleinian phrase that occasionally gets said on slashdot: There ain't no such thing as a free lunch (TANSTAAFL). Too bad that its wrong, since the universe is the biggest example of a free lunch in action.

      [ Don't feel so bad - my brain also seems hellbent to make me survive long enough to ensure my genes are passed on. Damn thing is that my body agrees with it and is planning to expire in half a century in order to free up resources for my future offspring. Its a comspiracy, I tell you... ]

      Just my $.02

      • Examine your assumptions (Score:4, Interesting)

        by naasking ( 94116 ) <naasking AT gmail DOT com> on Wednesday January 01, 2003 @01:49PM (#4994085) Homepage
        What makes you think there even was a beginning? Keep in mind that we have never actually seen the beginning of an event and the end; those boundaries are imposed by us. Reality is really a continuous cascade of effects which themselves become causes. How do we know there even is a beginning to the universe?

    • What is C relative to? (Score:4, Funny)

      by DesScorp ( 410532 ) on Wednesday January 01, 2003 @04:24AM (#4992881) Journal
      Dude......C is relative to B. It's C++ and Java that's relative to C. Cobol is a different species altogether.....

  • Comment removed (Score:3, Insightful)

    by account_deleted ( 4530225 ) on Wednesday January 01, 2003 @02:19AM (#4992615)
    Comment removed based on user account deletion

  • Quantum voodoo (Score:5, Funny)

    by Anonymous Coward on Wednesday January 01, 2003 @02:22AM (#4992627)
    Ya gotta love quantum physics... they make up the rules as they go along, and change them to suit as needed. Nothing is real until it's observed, and you will observe what you're looking for. So I named my cat Schroedinger, it suited him.

  • E != mc^2 (Score:5, Insightful)

    by Galahad2 ( 517736 ) on Wednesday January 01, 2003 @02:24AM (#4992634) Homepage
    Given this guy's equation, energy can NEVER equal mc^2, since a photon ceases to exist if it has no momentum. Of course, the limit as momentum approaches zero is mc^2, but who cares about Calculus anyway?

  • well, of course... (Score:5, Informative)

    by QID ( 60884 ) on Wednesday January 01, 2003 @02:24AM (#4992636) Homepage
    E=mc^2 is actually a simplified form of the real equation, E=mc^2/sqrt(1-v^2/c^2). A convenient graphical depiction can be found in a few seconds with google, or here: http://www.btinternet.com/~j.doyle/SR/Emc2/Derive. htm [btinternet.com].

    • Comment removed (Score:4, Informative)

      by account_deleted ( 4530225 ) on Wednesday January 01, 2003 @02:40AM (#4992697)
      Comment removed based on user account deletion

    • Quick review (Score:4, Interesting)

      by deblau ( 68023 ) <slashdot.25.flickboy@spamgourmet.com> on Wednesday January 01, 2003 @10:30PM (#4996374) Journal
      E=mc^2 is actually a simplified form of the real equation, E=mc^2/sqrt(1-v^2/c^2).

      Please don't forget your subscripts! As everyone learns in basic special relativity, total energy, which is kinetic + potential, is

      E = m0 * c^2 * gamma,
      where gamma = 1 / sqrt( 1-v^2/c^2 ) and m0 is the rest mass.

      At v = 0, gamma = 1 and E = m0 c^2, Einstein's famous formula for rest energy. Kinetic energy is given by KE = E - m0 c^2, or

      KE = m0 c^2 ( gamma - 1 ).
      To see any appreciable effect of velocity, consider the situation where you are going fast enough to double your effective mass (gamma = 2). Solving for velocity gives v = c sqrt(3/4) = 86.6% of the speed of light. Not gonna happen with current technology (outside of atom smashers).

      As v -> c, gamma -> infinity and this is Einstein's rationale for saying it's impossible to accelerate any matter up to the speed of light, since doing so would require an infinite amount of kinetic energy. On the other hand, the formula for photons is

      E = p c = h c / lambda = h nu,
      where p is momentum, h is Planck's constant, lambda is wavelength, and c / lambda = nu is the frequency. Since photons are never at rest (remember the constant speed of light?), you won't see any m's make an appearance here. And just for the record, this last formula explains the photoelectric effect, which is what won Einstein his Nobel, not E = m c^2.
  • Anyone else read this and get a flashback to an exam, say in college were you got the answer right but the prof. took off points because there was some slight flaws in your work or thinking. You were not wrong you just had a few things sketchy or didn't explain it well enough. One of those deals you just want to go insane on the prof on. Your right enough and nothing bad will happen with your result. Can just see a prof. pulling one of those on Albert.

  • Coincidence...? (Score:5, Funny)

    by CyberDong ( 137370 ) on Wednesday January 01, 2003 @02:27AM (#4992645)
    This story's at the top of the page, and look what's at the bottom:

    186,000 Miles per Second. It's not just a good idea. IT'S THE LAW.

  • I just thought of the funniest joke (Score:2, Funny)

    by Anonymous Coward
    Hope you like it:


    IN SOVIET RUSSIA,


    mc**2 = e


    Heheee. +5 FUnny,.

  • Even if his theories are improved (Score:4, Insightful)

    by backslashdot ( 95548 ) on Wednesday January 01, 2003 @02:35AM (#4992681)
    He will still be a great physicist that helped bring us to where we're at in science today.

    I dont see the big deal in "disproving" him. It's sad that people will take some sort of glee in thinking "Ha! Einstein was wrong!" Einstein himself would be glad to see people come closer in figuring out the natuer of the universe.

    Given the knowledge and tools available to him at the time, its amazing he came up with something in 1904 that people nearly 100 years later are still trying to figure out how to improve or disprove. Today we have the advantage of knowing how to look at things the way he did.

    Einstein's abilities, creativity, and ideas will have a permanent influence on humanity's acheivements.
  • Why can Google News post a link to The New York Times without pulling up the subscriber page and Slashdot can't?

  • Einstein knew he was wrong (Score:5, Informative)

    by automatic_jack ( 181074 ) on Wednesday January 01, 2003 @03:12AM (#4992760) Homepage
    Not more than a few year's after developing his theories of general and special relativity, Einstein realized that they weren't perfect. The simple reason behind his realization was that the theories of relativity didn't make sense when applied on a quantum scale, and the theories of quantum physics didn't make sense when applies of a relative scale. Einstein refused to believe that the universe worked in such a way that there had to be two mutually exclusive theories to explain physics on the very small and the very large scale.

    Of course, the rest of the world was busy experimenting with his theories of relativity, but after he published them he quickly lost interest in their progress. He spent the rest of his life searching for what he referred to as the "unified field theory," a single theory that could properly explain quantum physics and relativity at the same time.

    I'm not a physicist by any stretch of the imagination, but theoretical science does interest me. Brian Greene's book, The Elegant Universe [amazon.com] does a great job of explaining the background on this. It's worth a look.
    • Certainly he considered his work on the Unified Field Theory the most important thing he was doing. But he was up to lots of other stuff. Fequently he would mount challenges against some irrationality or other of quantum physics. (Usually the irrationality won, but not always.)

      In fact, Einstein was one of the unwilling architects of modern quantum theory. Because his challenges to it shaped the developing theory. And THIS was probably the actually most important thing he was doing.
  • 186,000 Miles per Second. It's not just a good idea. IT'S THE LAW

    Well, I thought it was a funy coincidence.
  • At this point, I would like to point out that physics is nothing by a model. Its a bunch of equations trying to create a model for what we observe so we can make predictions on the model. Now to explain an observation that is inconsistent with the model, we need to change the model. As it were - there are no "absolute thruths". Einstein's model and the theory based on it was astonishingly accurate and made amazing predictions. If our current observations are incosistent with the model - we need to revise it.

    By the way are all the comment posters the one who answered "I would be reading slashdot" for what would be doing during the new year ;)

  • -1, Disbeliever (Score:3, Informative)

    by murky.waters ( 596967 ) on Wednesday January 01, 2003 @04:28AM (#4992888)
    Actually not quite, I do find this issue extremely fascinating and I had thought of submitting this story earlier today, but I felt that there wasn't any actual news here. The thing is, currently, there is no evidence whatsoever that supports VSL (Varying Speed of Light) theories in any appreciable way, as the NYT writes, Superstring theorist super-star (as far as physics goes :) Edward Witten calls the whole thing "unimpressive". VSL is basically a product of physicists brainstorming to somehow come up with an answer to that most pressing question: just how to consolidate quantum mechanics (Bohr, Heisenberg, et al., about the really really small stuff) with Einstein's general relativity (mainly about gravity, big'n'fast stuff).

    It is actually not that much of a stretch. After all, when Einstein published his findings about ninety-eight years ago (I think), physicists abandoned the notion of absolute time (you have to spend a moment sometime to really appreciate what that means, most of the time, we really are Newtonians through and through). Today, some theoreticians and experimenters are considering to do the same with c, the speed of light.

    The idea that c varies, however, is not all that new, it has already been conjectured to be a function of time, c -> c(t), to make sense of some odd stuff in cosmology. What's new in Dr. Magueijo and other's work is that they play with the idea of c varying in much more complex scenarios, having to do with with position, wavelength, momentum, etc.

    It's worth mentioning that the latest shift in the literature tends to go to a varying alpha, the fine structure "constant", from which c can be seen to be derived from. For more info, check out this article [lanl.gov], co-authored by Magueijo (full text in pdf, on windows you have to add ".pdf" to the filename).

    Needlessly to say, there's dozens of scientific articles about this issue, some quite readable (I have a couple of links at home, writing this from a party I'm supposed to enjoy).

    The real news in all of this, it seems to me, is how almost esoteric science (in a good sense) has made its way into mainstream journalism. And with the publishing of Magueijo's book, which will be among the more readable ones of its kind, being scheduled for 2003, there's certainly a hot issue to watch as it unfolds. Last, unlike with superstring theory (you know, the little elastics swinging in 10 or so dimensions, and whose detection is so many orders of magnitude away from current technology, it ain't funny anymore), VSL is going to get some experimental underpinnings in 2006 from NASA's GLAST (Gamma Ray Large Area Space Telescope) satellite.

    Hey, with a little luck, who knows what the limit is going to be. It would be fucking amazing if we arrived at a correct Theory Of Everything within our lifetimes. Boy, what better issue for today.
  • Top 5 Rejected names for the new formula:
    (read the article before modding)

    Extra Special Relativity
    Relatively Special Relativity
    Double Secret Relativity
    Not Ready for Prime Time Relativity
    Britney Spears Nude !!!

  • Bummer (Score:3, Funny)

    by Tablizer ( 95088 ) on Wednesday January 01, 2003 @05:23AM (#4992998) Journal
    But

    E=mc^1.99999923850927642081748272

    is just not quite as catchy. Harder to fit on T-shirts also.


  • E=mc2 but only for large values of E

  • FTL == Time Travel ? (Score:3, Interesting)

    by steveha ( 103154 ) on Wednesday January 01, 2003 @06:59AM (#4993156) Homepage
    I'd like to understand why theory says faster-than-light travel is impossible.

    I do understand why you cannot ever reach or exceed the speed of light through normal acceleration. The closer you get to the speed of light, the more aparrent mass you get, and thus the more energy it takes to accelerate you. To hit the speed of light would take infinite energy (and you would have infinite mass when you hit it). Infinite energy and mass aren't really available, so you can't have a speeed >= C by accelerating, no matter how hard you try.

    The part I don't understand:

    I have been told that theory forbids any travel faster than light, no matter what the means ("warp drive", "hyperspace", "teleporter", whatever). My understanding is that if you could, some observers would see you traveling back in time, and this is forbidden.

    I would appreciate any explanation of this, or even just a pointer to a reference I can understand. Thanks.

    steveha

    • Re:FTL == Time Travel ? (Score:5, Interesting)

      by Soft ( 266615 ) on Wednesday January 01, 2003 @09:14AM (#4993369)
      I have been told that theory forbids any travel faster than light, no matter what the means ("warp drive", "hyperspace", "teleporter", whatever). My understanding is that if you could, some observers would see you traveling back in time, and this is forbidden.

      Yes. One of the hypotheses of relativity is causality, that is, one event can possibly cause another only if the latter occurs at a later time than the former, and this must hold true for all possible observers whatever their frame of reference.

      Now, as you know, the passing of time for an observer varies with his frame of reference (his speed, to put it simply). Hence, given two events, the interval of time from one to the other will not be the same for all observers. But if one is to cause another, it must always remain in its past; the sign of the time difference "t2-t1" must not change whatever the observer.

      Unfortunately, my memories of relativity are too scarce to put this into equations, but if you could travel faster than light, you could, say, watch an asteroid smash into the Earth and warn your friend on the Centauri stock market to sell shares of all Terran businesses before anyone could "see" the flash of the impact.

      And in a given frame of reference (maybe that of a traveler aboard a STL ship in-between), it would look as if you knew about it before it happened; stretching it further, it would be possible for the traveler (maybe through another FTL "jump") to warn Earth before the impact. Bye-bye causality.

      If these situations are not to happen, information must not travel FTL.

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