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Virtual Particles and The Law of Conservation of Energy

  1. Aug 16, 2011 #1
    Greetings all, I'm new here.

    I've looked through some of the topics on virtual particles and I'm still a little confused.

    In Philosophy, you don't get something from nothing. In physics, there's no such thing as a free lunch. Yet many on web pages about physics a claim is being made that "virtual particles" pop into existence from literally nothing. Zip. Zilch. Nada. No thing.

    I don't believe this for the following reason: the law of conservation of energy says that that energy can neither be created nor be destroyed.

    Law.

    This one time I was riding in the car with my wife who was driving and she'd got to talking and didn't realize that the traffic signal had turned red. I tried to warn her about the red light but she wound up driving through the intersection. So I said, "don't worry red is only a suggestion." Luckily, we didn't get into an accident and there weren't any cops around to give her a ticket.

    The laws of physics work a little bit differently, don't they? Though a law of physics may not be 100% certain, it is extremely, extremely reliable. Maybe 99.99% certain.

    The Law of conservation of energy says that that energy can neither be created nor be destroyed.

    Also, there is Einstein's matter equivalency E=mc^2. Matter can turn into energy and energy can turn into matter. No big deal.

    How does the Casimir effect work? Assuming the force measured is not caused by polarized molecules in the metal plates, doesn't the Casimir effect simply demonstrate that everywhere in the universe--the one we can detect and excluding various multiverse conjectures--everywhere in the universe there is a non-zero energy state?

    If as it is said that a positron and electron pair materialize in a vacuum, aren't they just materializing from energy that is already there and when they annihlate return back the energy that was already there?

    What are these physics web pages trying to say when they say virtual particles pop into existence out of nothing?
     
  2. jcsd
  3. Aug 16, 2011 #2

    ZapperZ

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    Please read the FAQ subforum in the General Physics forum. In particular, this has been addressed in this FAQ entry:

    https://www.physicsforums.com/showthread.php?t=511176 [Broken]

    Zz.
     
    Last edited by a moderator: May 5, 2017
  4. Aug 16, 2011 #3
    Thanks. I read the post.

    Look at my screen name.

    Have you ever seen the ventriloquist Jeff Dunham and his dummy Peanut? You know that Doppler effect sound Peanut makes when he waves his hand over his head? "Eeeeeyoooow!"

    Can you dumb it down for me a bit?

    This is a question that only requires a binary answer: either the positron and electron pair pop into existence out of literally nothing or they don't.

    Of course I will have some followup questions if the answer is that they do pop into existence out of literally nothing.
     
    Last edited by a moderator: May 5, 2017
  5. Aug 16, 2011 #4

    Drakkith

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    To my knowledge virtual particles are simply an interpretation of a mathematical concept to help with understanding the calculations or something like that. All I can really say for sure is that I've seen people much smarter than myself argue that they do/do not exist.
     
  6. Aug 16, 2011 #5
    That's where I'm confused. If they only exist in mathematical equations and not in reality then it's no big deal. But if as these web sites claim they do pop into existence from literally nothing and are literally real and not just used to solve maths equations then I have quite a few questions as to how this is so.
     
  7. Aug 16, 2011 #6

    Drakkith

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    Do a search for Virtual Particles here on PF. I'm KNOW theres a very recent thread on them, from the last month or two.
     
  8. Aug 16, 2011 #7
    Around 6:00, Mlodinow begins to suggest http://www.youtube.com/watch?v=BCoTGTRfDy0&feature=related" that virtual particles really exist. I think this is a strategy to change the views of Americans unfamiliar with such esoteric topics, and he thinks that they will trust him because he has a PhD from Caltech.

    Just one of the horrors of the implication of what you were describing in your previous posts..
     
    Last edited by a moderator: Apr 26, 2017
  9. Aug 16, 2011 #8
    I just read a book by Mlodinow on randomness. Good read. Sorry can't view youtube vids at work, but if the same vid is on google videos I can usually get to it through the firewall here at work.
     
    Last edited by a moderator: Apr 26, 2017
  10. Aug 16, 2011 #9
    @ FiziksDummy
    Try "From Atoms to Quarks: An Introduction to the Strange World of Particle Physics" by James Trefil (a physicist at Stanford). It has a nice discussion of virtual particles that you should be able to follow. And it's recommended (as particle physics reading for regular people) by Fermilab .
     
  11. Aug 17, 2011 #10
    But a lot of phenomena are "violating" the conservation law of energy, believed to be true. E.g. quantum tunneling. Perhaps the Schrodinger's equation (differential form) together with uncertainty principle implies that within short interval, energy can fluctuate. Though I haven't read much about it, I think information in this area is closely related to energy change.
     
  12. Aug 17, 2011 #11

    ZapperZ

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    Er.. how does quantum tunneling violate energy conservation law?

    Zz.
     
  13. Aug 17, 2011 #12
    Zeal,

    I don't see how quantum tunneling would be a violation of the law of conservation of energy. The energy of the mass of the electron doesn't change from one position to another. If energy is required to accomplish the quantum tunneling, then I would imagine that the energy is taken from the momentum of the electron and dissipated as heat. The electron is still an electron even though it has changed position
     
  14. Aug 17, 2011 #13
    Thanks. Will look into it.

    Let's try a different tack.

    Back in the day, before my time, even, there was this theory called the Steady State Theory. It was believed that the detectable universe existed forever and would continue to exist forever. Then Edwin Hubble discovered that galaxies were all rushing away from each other; that the detectable universe was expanding. This was before Lemaitre's Big Bang theory started to gain acceptance and the discovery of the CMB radiation by Wilson and Penzias.

    There was a big problem if the universe existed forever AND the universe was expanding. How are we able to observe any stars, galaxies, etc.? Shouldn't all of the matter have been spread out extremely thin infinitely long ago?

    To solve this problem astronomers (such as Fred Hoyle) suggested that as the universe expands new matter pops into existence (C-field) to form stars, galaxies, etc. thus preventing matter from getting spread out too thin to form galaxies, etc.

    The idea of matter popping into existence from literally nothing, I think, comes from Hoyle's C-field. And physicists may have thought there was something to it since the Casimir effect produced a force in a vacuum which seemed to demonstrate that (energy/matter) popped into existence from nothing and the idea just got stuck in the zeitgiest of physicists and probably textbooks ever since.

    Stephen Hawking said that the discovery of the Cosmic Microwave Background radiation drove, "the final nail in the coffin of the steady-state theory." Now we believe that the detectable universe has a finite past and evidently a finite amount of matter/energy (as opposed to an infinite amount of energy in an infinitely old, ever lasting, and ever expanding universe).

    Is, then, the idea of matter/energy (positron and electron pairs) popping into existence from literally nothing just a hangover from the outdated Steady State theory--Hoyle's C-field?

    Or, is there experimental evidence that demonstrates matter/energy popping into existence from literally nothing?
     
    Last edited: Aug 17, 2011
  15. Aug 18, 2011 #14
    If compared to classical situations, quantum that jumping through a potential barrier exceeds the original energy level. I think without considering laws in quantum mechanics, I would get the conclusion that it violates energy conservation law.
     
  16. Aug 18, 2011 #15
    But if you do not consider the quantum effects, and just apply classical mechanics which presumes that particles go continuously, then how particles penetrate potential barrier?
     
  17. Aug 18, 2011 #16
    I am just in high school, so I only know that in classical mechanics, continuity is necessary for conservation.
     
  18. Aug 18, 2011 #17
    Well, classical mechanics is not the best way to think about it--an electron, a point particle "drilling" through a barrier.

    I'm sure you are able to think of an electron orbiting a proton not like the moon orbits the earth but instead as an electron "cloud."

    If we are observing a hydrogen atom then there is a high probability that we'll find that electron somewhere in the cloud orbiting the proton of that atom. There is, however, an extremely low but non-zero probability that that electron could appear near the event horizon of a black hole at the center of a galaxy thirteen billion light years away.

    I'm sure other folks might be able to explain this better, but try not to think of an electron as a point particle but instead as a wave that fills the entire volume of the detectable universe. If we could construct a three dimensional coordinate system for the electron wave, there is some probability that the electron could appear as a point particle at any position anywhere in the coordinate system we constructed (anywhere in the entire volume of the detectable universe). While we are observing the hydrogen atom there is a high probability the electron appears somewhere in the set of coordinates that represent the electron cloud around the proton.

    In quantum tunneling all that is happening is the electron is changing from one coordinate (this side of the barrier) to another coordinate (the other side of the barrier). Notice too that I left out the fourth coordinate of time because the electron does not change position over time, but simply changes position. To us it appears to change position instantaneously.

    Change in position over time, or the presumption "that particles go continuously" is classical mechanics but not neccessarily quantum mechanics.
     
    Last edited: Aug 18, 2011
  19. Aug 19, 2011 #18
    I think electron cloud extends throughout the universe, while being far from nucleus, probability drops to very low level according to the RPD of hydrogen atom. probability that electron appears inside the Hydrogen atom is over 95%, because atomic radius is defined in that manner. In quantum mechanics, energy determines the shape of the orbitals, so where the orbital extends there is probability of finding electrons. But I am saying that applying classical mechanics which doesn't involve any orbitals would result in violation of laws of physics and therefore I think if you apply classical laws to virtual particles which is founded by quantum mechanics would result in mistakes.
     
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