Geist's Comments

No, light operates in our universe the same way everything else does. But traveling at the speed of light (as light is wont to do), time is stopped for it. Think about this: We can see light from stars a million light years away. From our perspective, it took a million years for that light that travel that distance to reach Earth. If you could ask the photon (a single unit of light) how long it took, though, it would say the trip was instantaneous. Photons just don't age.

Look at how we describe the speed of light: 186,000 miles per second. What happens is, as you travel faster, the second in that unit gets longer for you relative to whatever point you are traveling away from. If you are traveling at light speed, say away from Earth, a second of time for you would be an eternity (literally) on Earth.

Also, a stationary observer would never see you catch up to the light beam. In order for that to happen, you would have to go faster than the light beam and that just isn't possible. You can only get closer to trying to match speeds with it.

Another interesting caveat that emerges in the Relativity equations is that as your velocity approaches the speed of light, your mass increases (I forget how this works, but I remember the consequence) to the point your mass becomes infinite at the speed of light. A simple law of physics you may already be familiar with is that the more mass you have, the more energy it takes to accelerate that mass further. So the closer you get to the speed of light, the more energy it will take to make you go faster. Actually reaching the speed of light would take an infinite amount of energy because your mass will also be infinite at that point.

Holy crap! I wrote a book there. Sorry about that. :P

Let's try this a different way. Suppose you are traveling down the highway in your car at 60 MPH when you pass by your friend standing on the side of the road. You stick your hand out the window and wave. Your friend observes you passing by him at 60 MPH while he claims to be stationary. You, however, sitting motionless (relative to the car that is carrying you) observe your friend (and the rest of the world) passing behind you at 60 MPH. Which observation is correct? Well, they both are. It is equally valid for your friend to say you and your car are moving at 60 MPH down the road as it is for you to say that you are stationary and the rest of the world is traveling at 60 MPH behind you. It just depends on what point you use for reference.

Now you may be thinking, that's a pretty mundane explanation, I see that everyday on my way to the store. What does it have to do with Relativity? Relativity doesn't really take effect until you reach much higher speeds (which is to say, the effects are still present at the lower speeds we see everyday, but they are so subtle that they are hardly worth mentioning).

Suppose now that it is getting late and you want to get home. You push down the gas pedal and speed your car up to 75% the speed of light (you bought the sports model). It's getting dark so you also flip on your headlights. One of the things Einstein figured out with the Theory of Relativity is that while all motion in the universe is relative, the speed of light is absolute. It doesn't matter where you are observing from, it will always be the same (approx. 186,000 miles/second). As you flip on your headlights, your friend still watching you go by will observe the beam of light shoot forward out the front of your car at the speed of light, or about 25% faster than you are going. You, however, will see the same beam of light shoot forward at 100% the speed of light. Or, in other words, your friend would measure the speed difference between you and the beam of light to be 46,500 miles/s, while you would measure it to be 186,000 miles/s. Which observation is correct? Once again, both of you are.

Sorry if this is getting a little heavy. I'm not even sure I answered your question, but I kind of got off on a tangent there. I'll try and finish up here (hopefully this is till interesting to you). How can both observations be right when they are so different? Your intuition probably told you that if you are traveling at 75% the speed of light, you should have seen the beam of light leave your car at 25% the speed of light. Turns out the universe is a much stranger place than what our intuition often tells us (probably because we so rarely have to deal with relativistic speeds in everyday life, our brains just aren't wired for it). As you approach the speed of light, relative to your friend still standing on the side of the road, time slows down for you. A minute will take much longer to pass inside your car than it will in the outside world (or, to put it another way, if you look out the window you will see time passing in outside world much faster than it is inside the car).

If you got on a spaceship to Alpha Centauri (4 light years away, or 8 light years round trip) that could go the speed of light, you would find the trip there and back to take hardly any time at all. But once you got back to Earth, you would find that 8 years had gone by. Relative to the Earth, it took you 8 years to get there and back, but, because time moves slower onboard the spaceship (in fact, at the speed of light it stops altogether), it didn't seem like it took much time at all.

That was a very roundabout explanation. Hope I didn't lose you in there. To get back to your original question, the motion of an object only has meaning when described in relation to some other reference point. Just like in the first example: are you traveling at 60 MPH or are you stationary? It depends on if your motion is being measured in reference to some point on the side of the road, or the back seat of your car. Your velocity is still the same either way. Does that make sense?

Well...no. The atoms in your body are all moving the same velocity (we're not going to get into quantum mechanics here). But describing motion is useless unless you make it relative to some other point. All your atoms are going to moving with the same velocity (roughly) in relation to any other given point.

I did not nothing existed before the Big Bang. I said there is no such thing as before the Big Bang. In order to have a "before", you need time.

It wasn't.

Time was created during the Big Bang, so there really can't be a "before" the Big Bang. All you can do is try and look back closer and closer to the event itself. As it stands, current physical theory lets us look back to about 10^-43 seconds after the event, but going back farther our current equations start to break down into nonsense. Physicists are still working on it though!

The person behind the counter should have just accepted the payment. But she is under no obligation to give his car back until she has verified the payment by counting the pennies one...by...one.

Oh shoot, looks like it's time to close up for the day. Guess I'll have to count the rest tomorrow.

Not as much as it would have sucked to have been on the crew of Apollo 10. They went to the moon with a fully-functional LM, but their mission was to just undock the LM in lunar orbit, practice some maneuvers as if they were going to land (they brought it down to within 10 miles of the surface!), and then come back. How much do you think the pilot wanted to just bring the thing down all the way?

The "Who's your favorite astronaut?" poll cracked me.

Poor Michael Collins.

The real genius of this cartoon is revealed by this previous submission: http://www.milkandcookies.com/link/95550/detail/

Based on what little I can actually see through all the added effects, it seems to me these fights are amazing enough without the effects. They really just get in the way of something that would otherwise be very cool.

What show is this segment a part of? I think I want to try and watch the whole thing.

No it doesn't make sense. Ladies and gentleman of the supposed jury, it does not make sense!

Given some of the insanity that comes out of the religious camp (like, the banana is proof of intelligent design because it fits so well in the human hand, while 1000's of other fruits do not), if you don't know who Edward Current is, it can be really hard to tell the difference between his satire and reality.