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Flannigan on Photon Mass

  1. Sep 30, 2003 #1
    [SOLVED] Flannigan on Photon Mass

    I'm sorry.....gotta weigh in here. Light does have mass of sorts depending on what slant you take on it. Remember your theory from school.
  2. jcsd
  3. Sep 30, 2003 #2


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    Uh, sorry... maybe you should go review that theory, as you say. If your school taught you that light has mass, you really should burn that diploma and never speak of it again. There is only one kind of mass -- rest mass. There is no 'slant to take' on it. Light has no rest mass. If it did, it would not be an infinite-range force.

    - Warren
  4. Sep 30, 2003 #3
    Photons (which are the "particles" that make up light) have zero rest mass. To understand why photons "fall" into a black hole, you need to know a bit of general relativity. What general relativity says is that any massive object warps the spacetime around it. You can think of this with a simple analogy. Imagine a stretched rubber sheet that is completely flat. This represents the spacetime when there is no mass. Now, if you put a heavy ball in the rubber sheet, it will cause a distortion in the sheet. This is exactly what happens in space, except that it is in 3 dimensions instead of two.

    Further, a photon always travels by the shortest distance between two points. As spacetime is warped, the light appears to bend around a massive object. In reality, it is not that the object is attracting light, but it is just that the photons are traveling by the shortest distance in a curved spacetime.

    Around a blackhole, the distortion of spacetime is extreme. At the event horizon of a black hole, the spacetime curves into itself and as a result, light cannot escape from a black hole.

    At least this is the prescribed theory. I will conceed that there is no hard evidence at present but there is an effort afoot to find some. Remember the characteristics exhibited by the photon in lazer reflexion experiments where it appears to occupy two spaces at 90 degree angles from it's origin. When the light is measured in line it has x intensity. When split it has x+some intensity.

    Floyd W. Flanigan B.S.Nuc.H.P.
  5. Sep 30, 2003 #4
    In an old zinc mine 2,000 feet beneath the Japanese Alps, an international team of physicists has discovered that a ubiquitous, ghostly subatomic particle called the neutrino -- previously thought to have no mass at all, like a beam of light -- actually weighs in at about one ten-millionth the mass of the electron.

    That may not sound like much. But the long-awaited observation, to be announced in Japan today by the 100-member collaboration using the underground Super-Kamiokande neutrino detector, will force drastic revisions in long-established scientific theory and change the way researchers view a host of phenomena, including the shape of the cosmos.

    "These new results could prove to be a key to finding the holy grail of physics, the unified theory" -- the quest for deep, simplifying principles that underlie the profusion of objects and forces in nature, according to John G. Learned of the University of Hawaii, a veteran neutrino hunter in the Kamiokande group.

    The discovery strikes a devastating blow to the "Standard Model" of particles and forces, the consensus theory of how nature works at the most basic level. That model, hammered together over the past 75 years, governs the way scientists use nuclear energy, design transistors and lasers, explore space and build medical imaging devices, among scores of other endeavors. But it cannot accommodate a neutrino that has mass without changing several primary assumptions.

    "It really does shake up the Standard Model in a serious way," said Nobel physics laureate Leon Lederman, and "it shows us that we really just don't know nothin' " about the processes that give particles their bewildering diversity of masses.

    That shake-up, Learned believes, could lead "toward understanding of the origins of the matter from which we are made and the ultimate fate of the universe" -- namely, whether it contains sufficient mass that it will collapse upon itself, or so little that it will expand forever.

    There are about 50 billion neutrinos for every electron, and even the most seemingly barren voids of interstellar space contain a whopping 1,500 neutrinos per cubic inch. So if the particles have even a tiny mass, the universe is a much heftier place. Indeed, the collective neutrino mass could easily be "comparable to all the visible stars and the galaxies," said theorist Joel R. Primack of the University of California at Santa Cruz. That's a matter of considerable purport, since astronomers agree that at least 90 percent of the mass of the cosmos is in some unknown, invisible form called "dark matter."

    Neutrinos, first theorized in 1930 and undetected until 1956, are arguably the oddest of the 12 fundamental particles that make up all the visible matter known to science.

    There are three types, or "flavors," of neutrinos. All of them interact so faintly with ordinary matter that they usually pass unimpeded through space at nearly the speed of light. Tens of thousands stream through every human body every second; most could sail comfortably through a few trillion miles of lead without smacking into anything. As a result, they are almost impossible to detect, even by instruments buried far underground to shield the detectors from other incoming particles.

    "It's like trying to measure the mass of a dust particle that's on top of a baseball," said Jordan A. Goodman of the University of Maryland, one of 11 U.S. institutions in the collaboration. In fact, it has so far proven impossible to determine the mass of the neutrino directly. Instead, physicists study the phantom particles' behavior to see whether one type changes into another and back again over time in a process called "oscillation." Neutrinos could not oscillate if they were massless, so evidence of oscillation is tantamount to evidence of mass.

    Oscillation is made possible by the maddeningly strange rules of quantum mechanics, the system that governs the conduct of particles and forces at the very smallest dimensions. In the quantum realm, even entities with mass have wave-like properties and may exist in a number of different potential states simultaneously. Thus, viewed from a quantum perspective, a neutrino is not exactly a single particle. Instead, it is a combination of two different but coexisting flavors, each with a different mass. Over time, the waves representing each mass get in and out of sync with each other, and as one wave or the other predominates, the neutrino changes flavor.

    Or at least that was the theory developed to explain a couple of embarrassing problems. One is called the "solar neutrino deficit," referring to the fact that only a fraction of the neutrinos known to be created by nuclear fusion in the sun actually arrive on Earth. A similar deficit occurs in neutrinos created in the atmosphere when cosmic rays collide with air molecules. Physicists were obliged to either admit that they didn't understand neutrino production, or to assume that the "missing" neutrinos had oscillated to a flavor their instruments could not detect.

    From the 1960s through the '80s, various facilities made progress at observing neutrinos. Then, a few years ago, the Japanese decided to construct a huge detector in a mining site near the city of Kamioka. With assistance from the U.S. Department of Energy, they built a double-walled stainless steel tank the size of a small office building, containing 55,000 tons of ultra-pure water.

    Covering the interior walls are 11,146 special light sensors called photomultipliers that watch for the telltale optical signals given off in the rare event that a stray neutrino created by a cosmic ray in the atmosphere smacks into one of the atoms in a water molecule. When it does, the neutrino picks up an electric charge. Because it is traveling much faster than the speed of light in water, the now-charged particle causes the optical equivalent of a sonic boom -- a blast of blue light recorded by the sensors.

    One flavor, the electron neutrino, makes a characteristically fuzzy light pattern; another, the muon neutrino, produces a distinctively neat, clean ring. (The third type, the tau neutrino, has never been observed, though physicists are hoping to do so at Fermilab outside Chicago and elsewhere within the next few years.) After recording light patterns for 535 days, the scientists were finally able to show that there were roughly twice as many muon neutrinos coming downward into the detector from the atmosphere directly above than there were coming upward from the other side of the Earth.

    The neutrinos "that had traveled the longest seem to be disappearing more frequently," said collaboration member David Casper of the University of California at Irvine. Presumably they had enough time to oscillate into tau neutrinos (or perhaps some still unknown exotic flavor) that did not show up in the detector.

    "Massive neutrinos must now be incorporated in the theoretical models of the structure of matter," the collaboration announcement states, and "astrophysicists concerned with finding the 'missing' or 'dark matter' in the universe must now consider the neutrino as a serious candidate."

    Discovering Mass

    The farther neutrinos travel, the more time they have to change or "oscillate" into different "flavors." By comparing the number Aoming all the way through the Earth to the number coming from close overhead, physicists determine that neutrinos oscillate, which they can only do if they have mass.

    The Super-Kamiokande detector

    A 12.5-million gallon tank of ultra-pure water buried 2,000 feet underground to filter out other signals that mask neutrino detection.

    About once every 90 minutes, a neutrino interacts in the detector chamber, creating a cone of light that registers on the photo-multipliers that line the tank.

    Characteristic ring patterns tell what kind of neutrinos interacted and in which direction they were headed.

    SOURCE: University of Hawaii
  6. Sep 30, 2003 #5
    It was proven long ago (1901) that light has kinetic (mechanical) energy. [1]
    Those Einsteinians who came up with the impossible massless photon ignored it.
    Since it has said mass, then, what is the mass of light?
    The minimum mass can easily be found from using Planck’s Equation
    E = h. (1)
    equated to Einstein’s (minutiae skipped as they are not in the same system)
    E = mc2

    Planck’s Constant, h, only occurs in whole number multiples of itself. Therefore,
    what is the mass energy of a frequency of one single-cycle? One h!
    What amount of mass if transformed to energy, give this as ergs or result in light
    radiation of one single cycle/sec?
    Equating this energy to ergs to = h in ergs, for E in (2) then gives:
    7.372615 x 10-48 grams. That is the smallest quantum of mass, the neutrino.
    Therefore, what is the mass for any frequency?
    m = . x m. (3)
    PROOF: What is the mass of the radiation given resulting from the annihilation of
    an electron “at rest”? 1.23 . . . x 1020 x 7.37 . . . x10-48 = 9.109 . . . x 10-28 grams.
    What would happen if this gamma ray was converted in toto back to mass? It
    would give the mass of the electron “at rest”. Simply, all mass is composed of
    multiples of neutrinos and is, hence, the source of mass and, hence, the source of
    gravity. Ergo,
    E . m. (4)
  7. Sep 30, 2003 #6
    Actually the following analysis pertains to any particles whose rest mass is zero. If m = 0 then Eq. (E=mc2.3) is absurd, except in the rather useless sense that we may let become infinite. On the other hand, Eq. (E=mc2.14) works fine if m = 0. Then we just have

    - that is, the energy and momentum of a massless particle differ only by a factor of c, its speed of propagation. Although we cannot define because the massless particle always moves at c relative to any observer [this was, after all, one of the original postulates of the ], we can talk about its effective mass, which is the same as its kinetic energy divided by c2.

    Thus, even though light has no rest mass (because it can never be at rest!), it does have an effective mass which (it turns out) has all the properties one expects from mass - in particular, it has weight in a gravitational field [photons can ``fall''] and exerts a gravitational attraction of its own on other masses. The classic Gedankenexperiment on this topic is one in which the net mass of a closed box with mirrored sides increases if it is filled with light bouncing back and forth off the mirrors!
  8. Sep 30, 2003 #7
    No offense intended.....I am a scientist and I am sure you are a very impressive student. But yo cannot take everything at face value. Many of the 'science religeous' encounter the proverbial dogma of their mentor's slant on things. Always have a questioning attitude.....even if it is right in front of you in black and white....It might not be true.

    Floyd W.FlaniganB.S.Nuc.H.P.
  9. Sep 30, 2003 #8


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    Spacetime does not "curve into itself," whatever that means. At the event horizon, the escape velocity is c. That's all that happens there.

    - Warren
  10. Sep 30, 2003 #9


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    I have no idea what you think Super K and the solar neutrino problem have to do with the mass of light. Why are you spamming this forum with pages and pages of irrelevant, plagiarized stuff?

    - Warren
  11. Sep 30, 2003 #10


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    Funny, I always thought there was a "nu" in there. Thanks for showing me the light.
    Yeah, that's excellent. I'm glad you understand that energy and mass are interconvertible. It doesn't mean light has mass. Light carries energy and momentum, but has no mass.

    - Warren
  12. Sep 30, 2003 #11


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    I have no idea what "E=mc2.14" means, and I have the feeling you don't either. You're right, E = mc2 is not valid; it's a simplification of a larger formula:

    E2 = p2 c2 + m2 c4
    I find it ironic that the sources you cite agree not with you, but with me.

    - Warren
  13. Sep 30, 2003 #12


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    Ad hominem arguments notwithstanding (you don't actually know *anything* about me), light still has zero mass.

    I'm looking forward to seeing how the moderators respond.

    - Warren
  14. Oct 1, 2003 #13
    I am getting a sense of hostillity. Understand this, you are becomming defensive over a THEORY. No one is attacking your credentials here. No one is claiming you don't know what you are talking about. An alternate point of view has been presented. Nothing more. Nothing less. You obviously have some sort of chip on your shoulder and you need to understand that no one, least of all me, is trying to knock it off. This forum is for the exchange of ideas, not a game of 'king of the hill'. If the presentation of varrying viewpoint/theory causes you to feel the need to become agressive, perhaps the foundation of your belief in what you have been taught in school is a bit shakier than you are willing to admit. Just because you have a pile of books at the ready to defend your position does not make you ruler of the roost. And as for plaigerism, look junior... did I once say any of that stuff was mine? Did I lay claim to any of the research? I get paid over $100K/year for DOING the stuff you are STUDYING in your classes. Research did not stop the hour they published your textbooks and hopefully it never will. And hopefully you will tone it down a little and be a bit less confrontational toward those who choose not to agree with you.

    Floyd W. Flanigan B.S.Nuclear Health Physicist
  15. Oct 1, 2003 #14


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    Floyd, this always comes up, but when a physicist says 'mass' without any sort of qualification he means 'rest mass'. Yes, we are fully aware of the concept of relativistic mass, but we are also aware that these days in physics it is a not very oft-used concept.

    Reading what you have posted so far, I have to say I doubt your claim that you are a physicist.
  16. Oct 1, 2003 #15


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    Well, I'll be damned. Those sure did look like attacks on my credentials to me. I'll remind you again that you do not know me in any respect at all.

    In any event, I have to agree with jcsd. Physicists, second only to mathematicians, need to be very precise with their terminology. There are no alternative views of 'mass,' because the word mass is defined to mean one, and only one thing. You can debate all day long about what mass means, but know these two things:

    a) If you were a real physicist, you wouldn't be trying to get us to debate semantics.

    b) No real physicist will bother to argue with you about semantics.

    In short, you're making yourself look less and less credible with every additional word you type on this topic.

    The word 'mass' has one, and only one meaning recognized by physicists. Light has no mass, according to this definition. If you'd like to say it has mass-energy, or equivalent mass, or anything else -- go right ahead. If you'd like to say that light has mass, you are simply wrong. There are mountains of experimental and theoretical evidence that light cannot (and does not) have mass. If you really were a physicist, you'd already know all about the myriad of incompatibilites that would appear between a massive-light theory and experiment.

    Give it up.

    - Warren
  17. Oct 1, 2003 #16
    Sorry my posts aren't up to your expectations. As to my being a physicist, call Nuclear Management Company's HR department @800-216-1986 and ask them to verify my credentials. Also contact Trinity University @ Sioux Falls, SD and check to make sure my degree (B.S.Nuclear Health Physics) is the real deal. Admittedly I may not be up to speed on spme of the subject matter and my only excuse is that I have been concentrating my efforts elsewhere (utilizing BTU from spent fuel to create stored energy by elevating borated water and dropping it through a gravity turbine ala water fall and exacting viable electric production from heat we normally spend many dollars to get rid of via heat exchangers etc.) So my nuc. physics might be a bit Newtonian at present. I thought that's what this forum was about?

    Floyd W.Flanigan B.S. Nuclear Health Physicist
  18. Oct 1, 2003 #17
  19. Oct 1, 2003 #18
    That's a little redundant, repetitive, redundant and repetitive don't you think?
  20. Oct 1, 2003 #19


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    Yes, theriddler and you'll notice my earlier contributions to that thread. Invariant mass is just a far more useful defintion as otherwise you get the problem that your only talking about mass in one refernce frame though all reference frames are equally unprefered, so the best defintion is the rest frame of the object your talking about.
  21. Oct 1, 2003 #20
    well mass is measured in KG, or AMU's which is just a easier way of writing insanely small numbers, but most people relate mass to weight, and that would be an incorrect defenition

    if these "neutrinos" mentioned above exist, why do they make up electrons? I mean their name implies no electrical charge, I'm not arguing their existence, but merely asking where does the negative charge comes from
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