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Telescopes: Magnifiers or Time Machines?

  1. Apr 3, 2009 #1
    As I was helping my teenage kids with their science homework, I began to wonder if and how Einsteins theories on time/space relationship would apply to someone who was using a telescope to view a far distant Red Giant going SuperNova.

    Would using a telescope to view such an event result in our seeing the SuperNova before our being able to see it unaided, and if so, does that mean that the telescope is being used to view the SuperNova from a theoretical point far from Earth thereby, taking us back in time?

    Or, do telescopes just magnify the light that reaches the end of the telescope resulting in no time shift of viewing at all - that the light making up the telescopes image is exactly the same light which make up the image reaching our unaided eyes?

    Hope my novice question makes sense?
  2. jcsd
  3. Apr 3, 2009 #2


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    No you can just see an early point in the light curve. Those photons are arriving at you eye at exactly the same time it;s just there aren't enough of them to see.

    strictly speaking they collect more light rather than magnify it - but yes the photons arrive at the same time through the telescope as the ones reaching your other eye.
  4. Apr 3, 2009 #3
    Thank you for the reply.

    Is the speed of light the highest attainable speed at which any energy would flow from a SuperNova to us here on earth? If so, is there a specific spectrum or wavelength of light which travels at the maximum which over long distances could provide an earlier warning of a SuperNova prior to the visible spectrum reaching us?
  5. Apr 3, 2009 #4
    The speed of light is it. The wavelength has nothing to do with the speed that radiation travels. Furthermore, there is nothing special about the small slice of the spectrum that the homo sapiens species has evolved to detect with their eyes.

    On a related note, even the effects of gravity travel at the speed of light. If the sun were to magically disappear somehow, the earth would continue in its present orbit for about 8 minutes. We'd see the sun disappear at the same time the earth stopped being influenced by the sun's gravity.

    Nothing is faster than c.
  6. Apr 3, 2009 #5
    Thanks Jack.
  7. Apr 3, 2009 #6


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    True, but 'c' is the speed of light in a perfect vacuum.
    Even in interstellar space there are enough atoms to scatter off, that neutrinos will beat light from a distant supernova.
  8. Apr 3, 2009 #7
    Excellent point. I'm just an informed layman and not an astrophysicist (yet,) so I have a question to piggyback onto the discussion.

    Can you give a back-of-the-envelope estimation of how much sooner neutrinos would reach us than photons from a supernova 5000 light years away? How about if relatively nearby Betelgeuse goes supernova? That's about 640 ly away.

    In either case, would neutrinos beat photons by enough of a margin to give us time to point our telescopes in the right direction?
  9. Apr 3, 2009 #8
    My thoughts exactly. :)

    Additionally, as I look for ways to look back in time accross immense distances, do we have any actual non-theoretical proof that traversible wormholes(or any wormholes) actually exist and if so, do we have a way to measure how far the wormhole travels by measuring light as it travels to us from the same distant star both inside and outside the traversible wormhole?
  10. Apr 3, 2009 #9
    While on Betelgeuse, I have another noob question.
    It is said that the gamma ray burst from Betelgeuse going Supernova will not impact earth since we are not aligned with that starts rotational axis... yet, the image from Hubble shows one of that stars poles looking right at us. How tight is a supernova's gamma ray burst patterns as they exit from both ends of the rotational axis of the star?

    Do they travel in a consistent line/cylinder infinitely or spread out as an elongated cone over distance and therefore lose their denseness of energy as they travel?

    Sorry for the novice questions but my kids homework has lit a fire of curiosity about the Universe.

    What would be a good primer for someone who is an educated adult wishing to understand and learn about our current understanding of the Universe?

    Thanks for the help!
  11. Apr 3, 2009 #10


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    Wormholes are very unlikely to really exist. We can write down equations, using our knowledge of General Relativity, that in principle permit wormholes to exist, but there are all sorts of reasons why it is very unlikely that these exist in nature. For instance you require 'negative energy' to keep them open, which is a concept you can write down on a piece of paper, but which has no known physical manifestation (we have never seen anything that has negative energy).

    Another major problem is that wormholes would be unstable, even if you could form them, keeping them open for any length of time would be impossible.

    Wormholes are the stuff of science fiction, at least in the foreseeable future. They are impossible based on the physics we currently know, but of course we don't know everything (far from it!).
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