Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

An experiment showing a structure from 10^-18

  1. Aug 2, 2007 #1

    jal

    User Avatar

    The Ashoori group is claiming to have a picture of the ACTUAL energy density. (NOT the "wavefunction" associated with the particle).
    Something does not add up. We should not be able to “see” the energy density of something as small as 10^-18.
    -------------

    http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1686v1.pdf
    High-resolution spectroscopy of two-dimensional electron
    systems
    O. E. Dial_, R. C. Ashoori_, L. N. Pfei_ery, K. W. Westy
    July 11, 2007
    Don’t forget to look at page 16.

    --------------------------
    Quote
    http://www.fen.bilkent.edu.tr/~yalabik/applets/collapse.html
    Remember that the electron itself is a very small particle, less in size than the size of a point (a pixel) in the figure. However, the "wavefunction" associated with the particle typically may extend over a scale of tens of nanometers. At any time, the square magnitude of the wavefunction plotted in the figure would be proportional to the probability of detecting the particle at that point, if the whole plane was covered with electron detectors which would be activated at that instant in time. Only one of those detectors would then "click", with the corresponding probability. The wavefunction will then instantly lose its meaning and is said to "collapse".
    How the electron itself moves (whether it passes through one of the slits or both - or how the wavefunction is related to the actual electron) is a question that is not well defined in quantum mechanics - some would say that it is not a valid question.
    --------------

    It has to do with our understanding of what electrons and photons can or cannot do.
    It has to do with our understanding of the “quark sea” and the “drip line”
    Is the electron size 10^-18 or more?
    Is the pattern that was created a confirmation that there is a simple symmetrical structure at 10^-18 that is reflected in the position/structure of the electrons as shown by the Ashoori group?
    What kind of dynamics are going on inside the electron that make it possible for us to “see” it at larger scale?
    More of their work is at
    http://eprintweb.org/S/authors/All/as/Ashoori
    and they have a home page at
    http://electron.mit.edu/
    ------------
    What impact does this new info have for the theoretical side? (LQG)

    Maybe other forums would be interested in giving their inputs.
    (I already raised the question in my blog.)
    ------------
    jal
     
  2. jcsd
  3. Aug 2, 2007 #2

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    I'm not sure why the question regarding this paper is in the BTSM forum, since this is obviously a condensed matter paper.

    In any case, can you point out to me where exactly in the paper that they claim to be able to measure something of that scale? Remember, this is essentially a tunneling spectroscopy measurement that measures the density of states (not "energy density"). If you look in the caption to Fig. 2, they clearly indicated that their energy resolution is 170 micro-eV. This is not unheard of.

    Or do you imply that they can actually detect something the size of single electrons? This, too, is not all that new or surprising.

    Zz.
     
  4. Aug 2, 2007 #3

    jal

    User Avatar

    Hi ZapperZ

    I put this paper here because it raised a lot of questions for which I have no answers and it seem to conflict with other info that I have already found.
    I want to get opinions from a wider range of experts.
    I'm sure that the interpretations of the experiments at CERN will also get interpretations that will affect the theoretical side.
     
  5. Aug 2, 2007 #4

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    But you have ignored the rest of my question to you.

    I am very familiar with tunneling spectroscopy since I've done it myself. I still want to know how you ended up with the scale that you mentioned here just simply from reading this paper. To me, this paper raises no such questions that you have mentioned. Unless you are willing to answer what I asked and clarify how you actually derived at your conclusion, I would be inclined to conclude that you made a major error in interpretation of the experimental result and thus, this whole thread is moot.

    Zz.
     
  6. Aug 2, 2007 #5

    jal

    User Avatar

    ZapperZ
    Both of the following refer to 10^-17/18 for electrons.

    http://arxiv.org/PS_cache/hep-ph/pdf/0111/0111302v3.pdf
    Putting non Point-like Behavior of Fundamental Particles to Test
    Irina Dymnikova∗, Alexander Sakharov†, J¨urgen Ulbricht† and
    Jiawei Zhao
    24 March 2003
    Abstract.
    We review the experimental limits on those hypothetical interactions where the fundamental particles could exhibit non point-like behavior. In particular we have focused on the QED reaction measuring the differential cross sections for the process e+e− → () at energies around 91 GeV and 209 GeV with data collected from the L3 detector from 1991 to 2001. With a global fit L3 set lower limits at 95% CL on a contact interaction energy scale parameter _ > 1.6 TeV, which restricts the characteristic QED size of the interaction region to Re < 1.2 ?10−17 cm. All the interaction regions are
    found to be smaller than the Compton wavelength of the fundamental particles. This constraint we use to estimate a lower limit on the internal density of particle-like structure with the de Sitter vacuum core. Some applications of obtained limits to the string and quantum gravity scales are also discussed.
    ----------
    http://en.wikipedia.org/wiki/Orders_of_magnitude_(length)
    Orders of magnitude (length)
    -----------
    Do you want me to repeat my questions?
    jal
     
  7. Aug 2, 2007 #6

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    But now you're changing papers. I really don't care about this new one because it isn't in my area of expertise. The FIRST paper you cited is. It is of my professional opinion that you've read WAY more than the paper implied, especially when you cannot pin-point exactly where in that paper is there anything directly related to what you are claiming.

    Zz.
     
  8. Aug 2, 2007 #7

    jal

    User Avatar

    That is what theories are about. A fact from here a fact from there etc.
    I still have not received any comments on my questions.
     
  9. Aug 2, 2007 #8

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    But you are basing your "theory" on non-existent evidence, especially if you are basing it on that paper. That's my point when I said that this whole thread is moot if that was your starting point.

    I used to do tunneling spectroscopy in high-Tc superconductors. We routinely get energy resolution in the ballpark of what they do here. No where in there can we claim of detecting something of the scale you are talking about here.

    I believe that you have made a wrong interpretation of what they do in that paper. Thus, there are no valid comments that can be given to your questions, because your questions are based on a false premise that never existed from that paper.

    Besides, none of my original questions to you were answered either.

    Zz.
     
  10. Aug 2, 2007 #9

    jal

    User Avatar

    I have deducted ... you are right ..... .... and came up with questions that might have an impact on theories that need the sizes ... structures etc.
    Note: I am not claiming a structure in this thread. (my blog is something else)
    jal
     
  11. Aug 2, 2007 #10

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Then those questions are not appropriate since they are based on a misinterpretation of the results and the nature of the experiment. You really ought to understand a little bit more of the physics involved in the experiments you are trying to use. If not, you will be using results for inappropriate conclusions such as what is happening here.

    I wouldn't know, since I never read your blog. However, since you have made a mistake like this here, you might want to double check if you aren't doing the same thing already previously.

    Zz.
     
  12. Aug 2, 2007 #11

    jal

    User Avatar

    I will make sure to change/correct any errors.
    Could you give me your evaluation of the work being done by The Ashoori group?
     
  13. Aug 2, 2007 #12

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    1. This thread is in the wrong subforum.
    2. The paper is about doing contactless measurements of the DOS of a 2DES in different quantum Hall regimes and looking specifically at spin splitting. The ohmic versions of these measurements have been performed in dozens of labs around the world, though almost entirely at the Fermi surface.
    3. There's nothing related to the "size" of the electron or the "quark sea" in the paper. This is not Particle Physics - it's Condensed Matter.
     
  14. Aug 3, 2007 #13

    jal

    User Avatar

    Retirement should be a time to step out of the deep hole that people have created to become specialist, (The specialists have my highest respect). It’s an opportunity to become a generalist.
    It should not be a time to pontificate and “flame”.
    If you know something pertinent that can answer my questions, say so and give me the link.

    It is not just the theoretical people of LQG that need size and structural information at the quantum level.
    See
    http://en.wikibooks.org/wiki/Nanotechnology

    From Bee’s blog
    http://backreaction.blogspot.com/2007/07/consistency.html

    Also, from the thread
    In Compton scattering, does the electron absorbs a photon and then emit another photon with another energy??

    The derivation of wavelength shift in Compton scattering uses only the entrance and exit energies and momenta. It does not require a detailed understanding of the interaction. But the Feynman diagrams show an absorption and a re-emission.

    This is true, because the S-matrix formalism of QFT (which uses Feynman diagrams) is a simplified description of reality. In this formalism we care only about entrance and exit states, and don't ask about what happens in the middle. This simplification is a good match for scattering experiments in high energy physics. However, we shouldn't forget that between entrance and exit states the system undergoes some non-trivial time evolution. This time evolution is not accessible by modern experimental techniques, but it may be accessible in the future.

    -------------
    Respecfully yours,
    jal
     
  15. Aug 3, 2007 #14

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    There is a difference between being a 'generalist' and 'reading into something that is not there'. You were doing the latter.

    There are no "links" to give, because the mistakes that you made I have already explained (and so has Gokul). Furthermore, when I asked you for clarification (i.e. when I asked you to point out exactly where in that paper is there any mention of the length scale that is in your topic), you ignored it completely. If you are unable to elaborate or clarify something when asked, then either you yourself didn't quite understand what you were trying to do, or you simply made it up.

    Can papers and results from condensed matter permeate through other parts of physics. Definitely! I've always argued on this point (refer to Phil Anderson's broken symmetry principle). But is this particular paper a valid source to discuss "size" effects that you have in mind? NOPE! There are no links to be given here, unless you wish to go back to Tunneling in Solids 101, which is covered in Ref. 28 and 30 of that paper. So take a look there!

    Zz.s
     
  16. Aug 6, 2007 #15

    jal

    User Avatar

    Not everyone believes that physic goes to Planck Scale.
    Why Planck Scale. Why not stop at 10^-18?
    Let’s look at some papers.
    http://arxiv.org/abs/gr-qc/0601097
    Planck-scale physics: facts and beliefs
    Authors: Diego Meschini
    (Submitted on 23 Jan 2006)

    http://arxiv.org/abs/gr-qc/0506068
    Is empty spacetime a physical thing?
    Authors: Diego Meschini, Markku Lehto
    (Submitted on 11 Jun 2005 (v1), last revised 24 Oct 2005 (this version, v2))

    http://arxiv.org/PS_cache/gr-qc/pdf/0411/0411053v2.pdf
    Geometry, pregeometry and beyond∗
    Diego Meschini† Markku Lehto Johanna Piilonen‡
    Department of Physics, University of Jyv¨askyl¨a,
    FIN–40014 Jyv¨askyl¨a, Finland.
    November 10, 2004
    -------------------------------
    Maybe you think that he is a quack. Let’s see who he is associated with.
    Associations
    http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2729v1.pdf
    Spherically symmetric spacetimes in f(R) gravity theories
    Kimmo Kainulainen1,_ Johanna Piilonen1,y Vappu Reijonen2,z and Daniel Sunhede1x
    1Dept. of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyvaskyla
    2Helsinki Institute of Physics and Dept. of Physical Sciences,
    P.O. Box 64, FIN-00014 University of Helsinki, Finland
    (Dated: April 20, 2007)
    http://arxiv.org/PS_cache/astro-ph/pdf/0412/0412609v2.pdf
    Dark Energy, Scalar-Tensor Gravity and Large Extra Dimensions
    Kimmo Kainulainen∗ and Daniel Sunhede†
    Dept. of Physics, University of Jyv¨askyl¨a,
    P.O.Box 35 (YFL), FIN-40014 University of Jyv¨askyl¨a
    (Dated: March 16, 2007)
    ------------------
    Let’s look at some others who research Planck scale
    http://arxiv.org/abs/gr-qc/0305019
    Selected topics in Planck-scale physics
    Authors: Y. Jack Ng (University of North Carolina)
    (Submitted on 4 May 2003 (v1), last revised 15 May 2003 (this version, v2))
    Abstract
    We review a few topics in Planck-scale physics, with emphasis on possible manifestations in relatively low energy. The selected topics include quantum fluctuations of spacetime, their cumulative effects, uncertainties in energy-momentum measurements, and low energy quantum-gravity phenomenology. The focus is on quantum-gravity-induced uncertainties in some observable quantities. We consider four possible ways to probe Planck-scale physics experimentally:
    1. looking for energy-dependent spreads in the arrival time of photons of the same energy from GRBs;
    2. examining spacetime fluctuation-induced phase incoherence of light from extragalactic sources;
    3. detecting spacetime foam with laser-based interferometry techniques;
    4. understanding the threshold anomalies in high energy cosmic ray and gamma ray events.
    Some other experiments are briefly discussed. We show how some physics behind black holes, simple clocks, simple computers, and the holographic principle is related to Planck-scale physics.
    We also discuss a formulation of the Dirac equation as a difference equation on a discrete Planck-scale spacetime lattice, and a possible interplay between Planck-scale and Hubble-scale physics encoded in the cosmological constant (dark energy).

    http://arxiv.org/find/all/1/all:+AND+Ng+AND+Y+Jack/0/1/0/all/0/1
    Showing results 1 through 25 (of 38 total) for all:(Ng AND (Y AND Jack))
    ---------------------
    http://arxiv.org/abs/astro-ph/0312014
    Planck-scale structure of spacetime and some implications for astrophysics and cosmology
    Authors: Giovanni Amelino-Camelia
    (Submitted on 30 Nov 2003 (v1), last revised 8 Dec 2003 (this version, v2))
    http://arxiv.org/find/all/1/all:+AND+Giovanni+Amelino-Camelia/0/1/0/all/0/1
    Showing results 1 through 25 (of 94 total) for all:(Giovanni AND Amelino-Camelia)
    ------------------
    I have not read all of the papers or all of the citations but those that I have read contain answers/explanations that would be of interest to the moderators/experts of these forums. There is overwhelming evidence that you should not take the Planck Scale as an absolute unquestionable truth.
    There is a strong probability that 10^-18 could be the bottom of the scale.
     
  17. Aug 6, 2007 #16

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    You have the knack (or the propensity) of avoiding the issue. This is where I check out of this thread because it feels as if I'm talking to a wall. All I care about is that you did not bastardize the result of the paper you were touting about. I believe that has been accomplished.

    Please note that while it is a common practice for those in the subject area of string, superstring, LQG, etc. to extensively use the e-print ArXiv as the repository of unrefereed manuscript, *I* am not impressed by it unless it is published in a respected peer-reviewed journal. So if you are under the impression that citing for me a series of unpublished papers, you can save your effort into something that is more worthwhile.

    Zz.
     
  18. Aug 6, 2007 #17

    jal

    User Avatar

    What a terrible trick to play on ordinary person.
    I have been misslead into thinking that people who had doctorate degrees and were teaching at university knew more than little old me and that I could reliably quote them. :smile:
     
  19. Aug 6, 2007 #18

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Oh, so you have somehow closed your blinders on cases such as Fleishman and Pons, etc?

    You seem to have completely either forgotten, or ignored an important further step in the whole process of verifying the validity of anything in physics. Does a peer-review process mean anything to you? If you wish to quote someone before something has been verified, that's your problem. But do not fool yourself into thinking that you can sell it as "verified" to everyone else.

    Zz.
     
    Last edited: Aug 6, 2007
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: An experiment showing a structure from 10^-18
  1. On a scale from 1-10 (Replies: 89)

  2. Universe Structure (Replies: 0)

Loading...