Question 1

So...time doesn't actually slow down at near light speeds, but rather it's just the distance the subatomic particles travel increasing? Mind blown.

Accepted Answer

Or, to restate that per Ryan's explanation (in so many words), the biological effect of traveling at or near the speed of light is that time appears to slow down because subatomic particles have to move across greater distances in order for the chemical processes that cause matter to change to occur, thus aging does not happen as fast (time appears to slow down) as a body that is traveling much slower through space (photons travel shorter distance, aging occurs faster).

So, the secret to longevity is to do everything as fast as you can to stretch the distance those photons must travel through your body. No wonder that 58yo delivery guy from that sandwich shop still looks like an 18yo! :-)

So, the secret to longevity is to do everything as fast as you can to stretch the distance those photons must travel through your body.  No wonder that 58yo delivery guy from that sandwich shop still looks like an 18yo!  :-)

Question 2

When moving near light speed in one direction, the photons would be traveling at almost double the speed in the opposite direction you are moving though, right? Here's what I mean.
Say a photon wants to get from A to B.
A --------- B
P >>>>>> P
We are moving though, so the photon needs to go even faster.
A >>>>>> B
P >>>>>>>>>>>>>> P
But.... What if it wants to go the other direction?
B >>>>>> A
P <<< P
Wouldn't this even out the effect?

Accepted Answer

Good point. Your point does not assume all photons are travelling the same direction as a body traveling through space at or near light speed, but are likely travelling in random directions, some even the opposite direction as the body, in which case a photon may appear to move little to none as point B moves to the photon instead.

What can we expect the biological effect to be? Is there a way -- a formula -- to determine the aging process at a given speed?

What can we expect the biological effect to be?  Is there a way -- a formula -- to determine the aging process at a given speed?

Question 3

Can someone give me a list of einsteins laws?

Accepted Answer

Hmm... let's see...
(In no particular order)
Special Relativity
General Relativity
Brownian motion
Photoelectric Effect
Photons (Quantization of light)
Contributions to the development of Quantum Theory
Mass-energy equivalence
Introduction of the cosmological constant
Spacetime

And much more. Whew!

Question 4

In the example of the car in the first postulate, what is the significance of the windows blacked out as he said in 1:15?

Accepted Answer

So the system is closed and your reference frame stays within the car.

Question 5

What happens if the frame of the spaceship is considered? Also, does that mean that she actually _has_ grown and that the person left behind just sees her as the same age?

Accepted Answer

If the frame of the spaceship is considered, time passes much quicker on Earth than on the spaceship.  And she actually has grown/aged, just much slower than everyone else on Earth.

Question 6

how earth is an internal frame of reference?

Accepted Answer

Great question!
Consider a scenario in which only a car (driving on earth), earth (orbiting the sun), and the sun (not moving).
The car is moving relative to the earth. The earth is moving relative to the sun. Because the earth is a frame of reference, but also moving relative to something else (part of another frame) in our scenario, it is an internal frame of reference.

Let's take it a step further and add you into our equation: you are driving the car. You are moving relative to the car. The car is moving relative to the earth. The earth is moving relative to the sun. 
Now we have two internal frames of reference! We have one frame where the car provides the reference for the motion of you, another frame where the earth provides the reference for the motion of the car, and a final frame where the earth is moving. This means the car and the earth are both internal frames of reference.

I hope this helps!
If you want more explanation, ask me your questions in the comments for this answer and I'll do my best to answer them. 
Or watch this other video on the theory of relativity: https://www.khanacademy.org/partner-content/bjc/2015-challenge/2015-physics/v/bjc-special-theory-relativity

Question 7

Nice video. But you don't really need to 'prove' postulates.

Accepted Answer

Good point! However, he is not attempting to 'prove' it, he is showing why we are assuming it. It is still a postulate because it is "assumed true without proof", but he is trying to 'prove' why we assume it is true, to people who may not understand the logic behind the statement.
eg. Like some people may not understand 'Angle Side Angle' postulate for proving congruence. We can show examples, and explain the reasoning, but it is a postulate.
Also, it is not really "assumed true" yet, because it is still a theory.

Breakthrough Junior Challenge

Course: Breakthrough Junior Challenge > Unit 1

Special theory of relativity - 2015 Challenge Winner!

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