Recent content by alexg

  1. alexg

    Relativity and Speed of Light

    On the wiki page, there is one line stating that photons in superconductor have rest mass. However, there are no citations supporting that statment, and as far as I know, there are no transparent superconductors. All the wiki page can give is an upper limit for any mass, meaning no mass has...
  2. alexg

    What theories exist that predict our universe to be a star in a 'galaxy' of universes

    No, theories, as the word is used in science are not hypothesis. Theories are hypothesis which have been verified by observation and experiment. And I answered your question.
  3. alexg

    What theories exist that predict our universe to be a star in a 'galaxy' of universes

    No. All ideas about a multiverse are strictly hypothetical.
  4. alexg

    Speed of light in relative frames and acceleration

    An inertial frame is one which is not undergoing acceleration.
  5. alexg

    Proton decay

    Extremely sensitive experiments to detect proton decay have yet to find any.
  6. alexg

    Dark energy and the big bang

    No. There was nothing 'here' before the BB. Neither space nor time.
  7. alexg

    Relationship between expanding universe and time

    I would suggest The Inflationary Universe by Alan Guth. Again, he's just using an analogy to show how something (the universe) can be finite and unbounded.
  8. alexg

    Relationship between expanding universe and time

    That's where your error lies. It's not a model. It's an analogy. In this analogy, only the surface of the balloon is considered. It is using a two dimensional ANALOGY of the three dimensional universe. So for the purpose of the analogy, there is no inside of the balloon.
  9. alexg

    Expansion of space

    Andromeda and the Milky Way are approaching each other, and will collide in about 4.5 billion years. On any scale less than the local galactic supergroup (200 million lys) the effect of gravity overwhelms the force of expansion. It's only when you get outside the supergroup that you see...
  10. alexg

    New distant galaxy detected

    In the paper they say I think what they're saying is that the image they have is of a galaxy which is 'now' 500 million years old and which first formed at 200 million yrs.
  11. alexg

    No universe center why ?

    I would just like to comment that the balloon analogy seems to have caused more confusion than any other explanation of universal expansion. Of course, most of the confusion is because of people who don't know what an analogy is.
  12. alexg

    Highest expansion rate during inflation.

    If I'm remembering correctly, in the Guth-Linde version of inflation, the universe expanded by a factor of 1080 in the period between 10-45 and 10-35 seconds.
  13. alexg

    Is gravity 'weak' because it leaks into higher dimensions?

    The idea is not that there are 'other universes'. It's that unlike electroweak and strong force, gravity is able to propagate into the additional dimensions called for by M-theory. All those dimensions are part of our universe, but only gravity can move in those 'directions'. It would explain...
  14. alexg

    Why the black hole density is called the infinite density.

    Peter, a minor point, almost a diversion, but doesn't the Shell Theorem state that the gravity inside the earth remains the same until you reach the center? While there is more mass above you, you are closer to the rest of the mass on the other side, and it balances out.
  15. alexg

    CERN team claims measurement of neutrino speed >c

    Nothing in the Universe moves faster than rumor.