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Relic Photons and the Far Side of Elsewhere

  1. Aug 20, 2010 #1
    I have been looking at the new map of the universe created from data gathered by the European Space Agency’s Planck Telescope. The map has a red background containing gold flecks. The gold flecks representing radiation from fireball following the Big Bang, light that is thought to have been emitted only 380,000 years after the moment of creation. Whist thinking about these relic photons I imagined the existence of another earth like planet somewhere on the “far side” of the universe (in the distant region of space-time known as elsewhere that lies outside any light cone radiating from earth; where relativity forbids any signal to pass between us and our twin planet) and on that planet a space agency had launched a telescope identical to the Planck Telescope. Thus 13.7 billion years after the big bang on “opposite sides” of the universe the two telescopes gather radiation from creation’s fire ball. I also imaged that from a single excited atom in the fireball there existed a clear uninterrupted path to both telescopes. The atom emits its photon that starts its 13.7 billion year journey. As the relic photon nears the end of its flight astonishingly it will have equal probability of being gathered by either of the telescopes though these are separated by billions of light years.
    It is only at the moment when the photon interacts with a detector in one of the telescopes that the choice is made between our telescope and its twin on the far side of the universe. Up till that event both telescopes have an equal chance of capturing the photon. However, immediately the photon is captured by one telescope the probability of interaction with the other telescope vanishes. In fact the probability of the photon interacting anywhere vanishes everywhere within our 13.7 year old universe.

    According to relativity, the telescopes mutually lie in the other’s elsewhere and therefore there is no possibility of signals passing between them yet the probability of the photon interacting with the second telescope vanishes in response to it being captured by the first telescope. This situation is probably about the most extreme example of the consequences of wave-particle duality of light where the relic photon’s potential for interaction exists everywhere in universe but when it eventually interacts with a single atom in one of the telescopes the probability function collapses throughout entire 13.7 billion year old universe.

    This example perhaps is the most dramatic illustration of the difference in spatial distributions between that of the photon’s wave function and that of the actual interaction where the former is defined over the entire universe and the latter may be assigned a unique location relative to our reference frames. The photon seems to experience an instantaneous transformation from one state to the other which seems to imply an inconsistency with relativity although the example does not yield any measurable violation of relativity?

    In my opinion an account of this scenario must be one of the major tests for the validity of any theory that hopes to explain how matter interacts. My question is how well do any of the current theories weigh up against this condition?
  2. jcsd
  3. Aug 20, 2010 #2


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    I have seen other maps of the microwave Background, made using earlier space telescopes such as COBE and WMAP. Mottled blue and red ovals showing temperature variation. I have not yet seen a full map from the ESA Planck mission. Do you have a link?

    It seems to me your description of the basic oddness of quantum mechanics is quite clear and well thought out. You use cosmic Background photons (from year 380,000 of expansion) to illustrate the basic weirdness. I think you can see the same weirdness in conventional laboratory experiments such as, but not restricted to, the famous double-slit experiment.

    You could probably ask this same question in the Quantum Mechanics forum and get as good answers as here. It is a question about the foundations of QM, and about how we interpret things like the wave function---and how we imagine "collapse" of the wave function down to one of several concrete (i.e. classical) possibilities.

    As far as I know, none of the leading attempts at quantum-style treatment of gravity and its geometry is able to answer the question of why QM is the way it is. That is to say for example LQG (loop quantum gravity) does not address the issue of QM foundations weirdness---why microscopic wave-governed behavior is different from what we big macroscopic lummoxes experience in our macroscopic world, and find intuitive.
    In this sense, LQG is just like any other quantum theory---it takes the odd unintuitive character of QM for granted and assumes it and uses it just like every other theory does.

    It is cold comfort to point out that the paradox you point out can be reproduced, in its essentials, in a normal-size room in the lab. You don't need the whole universe to illustrate the conundrum.
    Last edited: Aug 20, 2010
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