U Cant Cross C
U Cant Cross C
U Cant Cross C
broken?
How could we make it move even faster than S[5,000]? By making it weigh nothing at
all! If the more something weighs, the more energy you need to push it, the way to get
the biggest bang for your buck is to make the object you're pushing weigh nothing at all.
Imagine how fast you could throw a baseball if it was totally weightless!
Alas, we can't make the Enterprise weigh nothing at all, but there is something that does
weigh nothing: a photon. (Again, strictly speaking, a photon has no mass.) A photon is a
particle of light. Since light particles weigh nothing, they can travel the fastest it's
possible for anything to travel, which is, in the system I made up, maybe S[5,001].
As it happens, we know the real value of S[5,001]. It's around 180-thousand miles-per-
second. That's how fast something can travel if it weighs nothing. And, if you think about
what I wrote above, if it weighs nothing, it requires no energy to push it. As soon as you
add a little weight to something, it requires energy to push, and the faster you push it,
the more energy it requires. To push an object with weight (mass) at 180-thousand
miles-per-second, you'd need more energy than exists in the Universe. So you're shit out
of luck, Captain Kirk!
The lingering question here is why 180-thousand miles per second? What's magic about
that? Why can't a photon travel faster than that? (Why can't light travel faster than the
speed of light?)
As far as I know (again, Physicists, please correct me if I'm wrong), the answer to that
is because. Because that's just the way our Universe is built. It's a physical law we
acquired by being a product of the Big Bang. If there are other universes, perhaps the
constant is faster (or slower) in some of them.
When we get to a certain base level of "why?" questions, the answer is always going to be
"because." Our universe seems to be a game with certain rules (the Laws of Physics).
Why those rules and not other rules?
Because...
UPDATE: I asked Joshua Engel (who has a degree in physics) to look this over and
critique it. Here's what he sent me in an email, posted with his permission:
It's pretty good. It's not really "fundamental", but then, most askers aren't really
prepared for "fundamental" answers. All we can do is throw out a series of
approximations and hope that one of them fits the actual level they're at.
We can say a little more than just "because" when it comes to why the speed of light is
what it is, though it rapidly gets out of an area I'm comfortable talking about. Within
special relativity, you can say it's because space "just is" the Minkowski metric
(s^2=x^2+y^2+z^2-(ct)^2), and it's the fact that s is independent of all observers that
lets you solve for c and get the answer we get. (In particular, s=0 for light).
If one understands general relativity, one can take it down a few steps further, to
fundamental shape-of-the-universe constants like the Ricci tensor and the Ricci scalar,
and generalize that to branes and such gibberish like that, but that's far beyond my pay
grade.
So no matter where you go, there's always an "it just is", but for practically all people the
"it just is" has more to do with the amount of study they've put in rather than what is
known or can be known.
Instead, we throw a variety of arguments, all based on the same thing as users, and see
what "sticks".
The one quibble: photons do have mass, in the sense that they have energy and E=m
(with an extra c^2 constant in there to make the units work out). They don't have any
energy if they were stopped, because they have no rest mass. They get their energy from
the extra E=pc component that most people leave out of the equation: they have no mass
but they do have momentum. If you get whacked by a photon, you get pushed; that's how
solar sails work.
That's exactly where your argument goes: when you take the limit of mass to zero, you
get a photon, which has no mass at rest and therefore can never be at rest, or in fact at
any speed other than c, which is the only one where the various infinities cancel out to
yield a non-infinite value.