<== A stereotypical
representation of an anonymous atom with nucleus and four electrons.
===> A more modern and
exotic depiction of the atomic structure of a single-walled carbon nanotube.
Chicken-Little Physics - The
other day I read that our universe will neither expand endlessly, nor
collapse back into the single point from which it began its expansion. No!
It will keep expanding until it rips like a rotten old shirt! This
ripping will start with clusters of galaxies, proceed to shred individual
galaxies, then individual stars and planets like Earth, and finally, we
humans will be peeled apart in layers, starting from the outside. Get
ready! This is supposed to happen only 50 billion years from now! To
be somewhat serious, I have a hard time getting my mind, or is it my
imagination, around some of the concepts of modern astrophysics.
Light and Distance - One
interesting postulate is that there is no "now" at light distances.
The speed of light being finite at 186,000 miles per second, a light
distance is one that can only be measured by the time it takes light to
travel it. For instance, Proxima Centauri, the nearest star to our
sun, and its neighbor, Alpha Centauri, are four light-years away. One
might possibly ask here on Earth, "What's going on right now on Proxima
Centauri?", but one can never find out, not even with an hypothetical
telescope powerful enough to get a close-up view. The light reaching it
would be four years old, and whatever we saw would be what had happened four
years ago. What really mystifies me is that (supposedly) the galaxies
at the outer fringes of the visible universe are moving away from everything
else in the universe at great speed. Because they're so far away, the
light reaching us from them is billions of years old. So there's
really nothing out there where those most distant galaxies were billions of
years ago, is there? That's a "maybe, actually". We just don't know
and can never find out. If they've been moving away from us all that
time, where are they now, or does that question even make sense?
Scientists used to say that the universe would stop expanding and collapse
back in on itself because of gravity. Now they postulate "dark matter"
spread throughout the universe, which has an opposite effect from standard,
garden-variety gravity, pushing everything away from everything else.
When I say "postulate", I mean that dark gravity cannot yet be physically
demonstrated to exist, but that
mathematical analysis of the behavior of matter, light and
other aspects of our universe necessitates that it, or something with
the same properties, exists. I think it would be extremely interesting to
imagine the speed of light to be infinite, that Michaelson and Einstein had
it wrong. What fun!
Relativity - No doubt some of
you know much more about this than I do. Feel free to email
corrections. I correct well. I'm a layman, not a scientist, and
I definitely don't understand the mathematics underlying anything I've
written about here. I do enjoy non-mathematical explanations of
relativity.The speed of light is always the
same relative to the absolute physical space in a vacuum and in a zero
gravitational field. This has become axiomatic. Let me try to
illustrate it briefly. If I'm on a ship going 25mph (whatever that is
in knots) and I walk rapidly forward, my speed is 25mph plus my walking
speed of, say, 3mph. That is, 28mph. If I turn around and walk
toward the stern, my speed becomes 22mph. But, if I shine a beam of
light from one end of the ship toward the other, the velocity of light
remains the same no matter in what direction I aim it. Yes, the speed of the
ship is negligible relative to the speed of light. But in a spaceship
moving at, say, 90% of the speed of light, the effects would be enormous.
Consider this: d = vt; t = dv; v = dt. If the velocity cannot vary,
what then? More to come.
