Most Active Topic:  Relative motion

Hello, and it seems a lot of the Powder Toy community is made up of some very smart teens/kids/some adults.

I thought, rather than fill this entire subforum with science and math stuff, as it seems to be starting to be filled with it, why not condense it all into one thread?

Basically, discuss anything and everything science and math, fun facts, and any questions you have about science and math, as I am sure they'll be answered.

The most active topic that I find whenever I check this thread will be posted up at the top of this post.

I'll start with a little something interesting:
Do you want to know where "relativity" got its name?  It comes from the idea that all measurements of speed has to be measured "relative" or in reference to another object.

To clarify, you are sitting at your desk moving seemingly 0 mph(I'll use Imperial units because it is the one I am most familiar with in terms of speeds of certain things, though I prefer metric in measurement), right?

But in fact, this is only relative to the ground and the small objects around you.
If you shift your reference point to the center of the Earth, you are spinning at 1015 mph around it, or roughly 450 m/s if I remember correctly.  You are not being thrown off from the Earth because of gravity.  There is a certain horizontal speed that escapes gravity, but that is another subject.
Shift your reference point again to the center point of the solar system, the Sun, and you are spinning at roughly 64,000 mph around it, also being held by gravity in an orbit(I'll discuss orbits when the topic comes up, you can ask about it if you are interested)
Now again, shift your reference point to the center of the Milky Way, a supermassive black hole, and you are moving several hundred thousand or possibly million mph around it, held by gravity and dark matter(Another subject).
Now, you are stuck(Until we find the center of the universe, if there is such a thing, and if it is considered motionless), and this is another important concept in special relativity.

The concept of special relativity is that there is no absolute reference point.
That is, there is no such thing as being able to measure yourself against something completely and totally motionless.
This can also be stated as there is no absolute state of rest(Motionlessness).
But, a strange thing that special relativity also states, is that the relative speed of light remains the same for all observers.  Basically, C is a constant, and does not change.
Now, the consequences of this may not be obvious at first, but that is a REALLY complicated subject and I don't think it should be brought up lest I confuse some people.

To relate it to real life:
You are in a car, going 60 km/h.  There is another car going 60 km/h alongside you.  It seems motionless in relation to you, even though you are both moving.  Now, another car is going 60 km/h in the opposite direction, and it seems to be moving twice as fast.  Yet another car is going 0 km/h, but it seems to be going 60 km/h to you.
Another example:  You are standing in a bus going 50 km/h.  The other people in the bus seem to not be moving, but you look outside, or shift reference points to the outside, and you see you are going a decent speed, even though the people around you are not moving in relation to you.

If you need me to help clarify the concept more, I'll be glad to answer any questions.  Thank you if you read this far, and I applaud you for your interest in science if you read this far.