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Elementary particles of universe

  1. Nov 10, 2011 #1
    I've read everywhere that strings are now taken to be the fundamental particle, but I think that it is taken as one because we cannot go further. After a few years once we can go in we may discover a new elementary particle.

    I was thinking; isn't energy the fundamental particle? Because even the now supposed particle strings are vibrating and anything that has mass has energy!!!
    Last edited by a moderator: Nov 12, 2011
  2. jcsd
  3. Nov 10, 2011 #2


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    Welcome to PF Achyut!

    First off, we discourage this kind of terse and abbreviated writing style. Please take the time to create legible posts.

    Secondly, strings are hypothesized to be fundamental in string theory. The theory itself predicts that there is nothing smaller. Of course, string theory could be wrong.

    And discovering new particles by pushing the energy frontier, like what's happening right now at the LHC, is not about discovering more fundamental constituents of the already known particles of the standard model. It's about finding new, heavy fundamental particles.
  4. Nov 12, 2011 #3
    Sorry for writing in abbreviated style....!!!

    But my question is that any thing in this universe has energy....so cannot energy be the fundamental constituent of universe....
  5. Nov 12, 2011 #4


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    Yes, sure.
  6. Nov 12, 2011 #5


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    Energy is always a property of something. More precisely, it's a property of the relationship between two or more objects. The objects come first, therefore energy cannot be "the fundamental particle."

    "Pure energy" exists only in science fiction.
  7. Nov 14, 2011 #6
    But still doesnot energy define mass???
  8. Nov 14, 2011 #7
    Are you refering to the way mass can be converted to energy? eg. when matter and anti matter collide?
    This doesnt mean Fermions (matter) and made up of photons (force carriers).
  9. Nov 24, 2011 #8
    While matter (fermions) may not be neccessarily made up of photons, it does seem to be the case that matter and energy are two different expressions of the same fundamental substance, correct? Kind of like a quarter has heads and tails, but it is not made up of heads and tails. The quarter is actually made up of an alloy of nickel and copper (i believe...).

    In this sense, matter and energy are both made up of strings, assuming you believe in string theory. As strings are themselves considered to be the fundamental building blocks of everything in the universe, the chain of regression cannot be taken any farther (again, assuming you buy into string theory, which I tend to). In this kind of framework fermions, photons, bosons, and indeed every particle we can theorize or detect would be some permutation of string combinations.

    When you look at the nature of energy exchanges in the light of string theory, the photons, gluons, gravitons, and other messenger particles are actually nothing more than strings (either single or several together) that are packaged together by the sender and transmitted to the reciever. The transfer of "energy" becomes a transfer of fundamental strings which changes both the constitution of the sender and the receiver. This change in constitution is expressed by an alteration in the energy states of both sender and receiver.

    Once again, this explanation depends on my admittedly limited understanding of string theory and your willingness to accept the conditions and precepts of the theory itself.
  10. Nov 25, 2011 #9


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    Your explanation does not rely on string theory. In your explanation, replace everywhere the word 'string' with the word 'particle' and the conceptual meaning is retained. One does not need to accept string theory to accept that fundamental particles are, well, fundamental.
  11. Nov 25, 2011 #10

    While this is true, I don't know of a theory for fundamental particles that really explains the matter-energy exchange and equivelancy. If you find this fundamental "particle" then will that also be what makes up energy? Will it be what makes up photons, electrons, bosons, etc. ? Under standard particle physics it would appear that one set of fundamental constituents are needed to explain fermions, and a completely separate set of fundamental constituents are needed to define bosons, photons, and other messenger particles normally associated with energy exchanges.

    Conceptually, I think string theory does a much better job explaining those things, and that's what I was trying to show in a general kind of way. I didn't want, at the time, to get into how the wavelength properties of photons can be described by the vibrational modes and harmonic resonances in fundamental strings. Or how string vibrational modes effectively describe, define, and predict the graviton. I was trying to focus simply on how string theory can remove the need for a matter to energy conversion by describing both "matter" and "energy" as different ways to assemble the same thing.... i.e. strings. I guess if I'd included more of the nuts and bolts it would have been more apparent that an acceptance of string theory was neccessary in order to accept my brief explanation.

    Although, to be fair, in order to accept that photons are packets of strings, and that the loss of strings accounts for the loss in apparent mass that matter undergoes when it emits radiation, you kind of have to accept string theory. Otherwise the part about exchanging strings just doesn't make sense. (okay, maybe that last part was sarcasm... haha)

    I guess what I'm trying to say is that while I can see that what you're saying is verbally true, I don't think it is conceptually valid with regards to string theory explanations vs. point particle theory explanations. If one of the LHC runs were to some how unveil a truly fundamental point-particle, I guess I'd be proven wrong.... As it stands, though, with only theoretical basis to draw conclusions about fundamental building blocks of reality, I think string theory does the best job of describing things as we see them.
  12. Jan 5, 2012 #11
    New here and new to physics, but have a lifelong interest in ALL sciences.

    I have read The Elegant Universe and many other books and articles on Super String Theory. This thread (is that a pun?) seems to be the right place to ask my burning question...if strings are made of energy, what is energy made of???

    I have a sense that just as the universe seems to have no outer limit, the innerverse will also seem to have no inner limit, but I just wondered if anyone has a hypothesis regarding what is smaller than a string?

    Thank you, and sorry for my (probably) very elementary question.
  13. Jan 6, 2012 #12
    Actually, many of the attempts at combining QM & GR do place a limit on how small things can get (assuming that is what you meant by no limit to the innerverse?). String theory for example posits that strings are on a size scale of the planck length (minimum - this is not to say that some strings are not larger than the planck length; just none smaller) If you attempt to probe realms smaller than this, mathematics break down and produce nonsensicle answers (infinities). It seems like looking at a smaller scale than this is physically meaningless.
  14. Jan 6, 2012 #13


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    Welcome to PF QRUIS!
    Why does it need to be made of something more fundamental? You've gotta be able to start somewhere, or else this reasoning can be applied ad infinitum.
    If space is continuous, then we can indeed consider even the most infinitesimal of length scales. If space is quantized, however, then this discretization will impose a minimum length scale (perhaps at or about the Planck scale).
  15. Jan 6, 2012 #14


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    But strings are not made of energy.
  16. Jan 16, 2012 #15
    Energy seems to have originated from somewhere or something as did everything else we observe. Right now we call it the big bang.

    Describing a string as a one dimensional filament of vibrating energy is ok. String theory also leads to two dimensional "strings" called branes..meaning membranes....like p branes and d branes. Since we haven't really observed them yet experimentally, we could argue forever about what they 'really' represent. At Planck scale, strings seem to exhibit "duality"...called 'T' and 'S'...for example, they may reach a minimum size and then seem to grow.

    The analogous component in broader quantum mechanics would be wave mechanics (Schrodinger) add (Heisenberg) matrix mechanics, which have been shown to be equivalent models with different perspectives. Debroglie suggested that matter exhibits both wave and particle characteristics; matter is quanta (a 'particle' or localized lump] of radiation (energy). These are statistical in nature and have all sorts of interesting properties like "Pauli exclusion" and Heisenberg "uncertainty" and also exhibit some 'minimum size" or limits on measurement accuracy...and scientists would like to better understand the connection between quantum theory and general relativity, called 'unification'.

    At really,really,really high energies (and temperatures) several energies have been tied together in a common origin (the strong,weak, and electromagnetic forces) in the standard model of particle physics. These seem to be "unified", were one entity, at the big bang. Gravity has not yet been included nor has time....nor mass.

    And of course there are lots of missing pieces and obstacles in each of these theories. everything may have had a common 'form' at the big bang, something that only exists at extremely high energy (and temperature) and as far as I know, nobody knows what caused the bang in the first place.
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