Time is not motion, time is duration!
Light travels 1 distance in one duration of time. If your clock doesn’t agree with the speed of light, then your clock is WRONG! I don’t care if it’s an atomic clock or not, if two atomic clocks read a different amount of time, the clock(s) that don’t agree with the speed of light are wrong. Light doesn’t take 2 different amounts of time to travel a distance, period!
Duration is a bucket filling with water, sand flowing through an opening, the swing of a pendulum, the vibration of crystals, …
How many times does the Earth orbit around the Sun in one spaceship caesium second versus how many times does the Earth orbit around the Sun in one earth caesium second?
No. the duration depends on the speed of the spaceship.
It has to go pretty fast to make a difference though.
the calculations show that at 25% of the speed of light, the effect is just 1.03 (a mere 3% slowing of time or contraction of length); at 50% of the speed of light, it is just 1.15; at 99% of the speed of light, time is slowed by a factor of about 7; and at 99.999, the factor is 224.
Not sure what you are trying to say here. Since “processes in motion” could include a camera flash, which is at the speed of light then you comment is obviously false since the earth is very slow compared to the speed of light.
Wrong, that is motion, which occurs over a duration of time. Duration exists whether you measure it or not. If there was no objects in space, there would still be duration.
There is distance whether you have a ruler to measure it with or not.
There is duration whether you have a clock to measure it with or not.
Distance and time are inevitable, we humans simply devised a scheme to have a standard measure of them.
A ruler measures distance, and a clock measures duration (time). Take the ruler and clock away and your measuring devices are gone, but distance and time still exist.
You seem to think the earth orbiting the sun is some kind of universal time keeping device. It is not.
I can travel at such a velocity that when I return to earth, 200 years have passed on earth and 20 years have passed for me. The fact that the earth has gone around the sun 200 times in my absence is totally irrelevant to my own elapsed time.
The word “year” means “the time it takes for the Earth to orbit around the Sun”. Are you saying it’s possible for you to travel at such a velocity that when you return to Earth, the Earth has gone around the Sun 200 times for people on Earth and only 20 times for you? Either that or you are changing the definition of the word “year”. Whichever way you look at it, the elapsed time remains the same.
I thought that one way to prove that two processes (e.g. the atomic second on spaceship and the atomic second on Earth) are taking the same amount of time is by comparing them to some other process (e.g. the Earth orbiting around the Sun.) If one takes half a revolution and the other takes two revolutions, they aren’t really equal in duration.
The fact that light travels a path length of 200 light years during the time you are gone means your clock is wrong. If your clock reads 20 years for light to travel the distance of 200 light years, you need a new clock, yours is broken!
How is that done? 
The duration of a second is the same on the spaceship and on earth : 9,192,631,770 cycles of the hyperfine structure transition frequency of caesium-133 atoms. That’s the definition of a second.
I mean that everything that happens on the ship is consistent with the time shown on the clock. The aging of the people, the rusting of the metal, the functioning of the electronics, the lifecycle of the bacteria or fruit-flies, etc.
It’s not like the clock is broken is some way or it’s the only thing affected.
I don’t think that is legit logic.
In the end they are saying (with 3 observers) that whoever has the fastest watch is the one not moving. That is presuming something - that in the universe there is an absolute still where watches always run as fast as possible.
If it occurred as that scenario suggests - it would prove that there is an absolute reference.
Merely by looking at their watches - how would they know that the third observer wasn’t still as observer’s 1 and 2 passed by but as different speeds (2 traveling at twice the speed of 1). Observers 2 and 3 would still show a duration of 1.5 but observer 1 should show a markedly less duration - perhaps .75 or something - because observer 1 would be traveling twice as fast in an absolute frame. Because his watch did not show time dilation - “he must have been traveling slower with respect to universe/absolute stillness”.
So something is wrong with his explanation.
You want to go to a planet 21 light years away.
You predict it will take just over 42 years to make the round-trip at 0.99c.
Get in your ship. Instantly accelerate to 0.99c. Fly. Instantly stop. Have a picnic. Instantly accelerate to 0.99c. Fly back. Instantly stop.
Check earth calendar. It shows that you have been gone for over 42 years.
The clock and calendar on your ship shows that it took just over 3 years to fly there and 3 years to fly back. You only aged 6 years. Your cat, which was on board to keep you company, only aged 6 years.
Right. And if we define the word “second” to mean “the time it takes a sweep hand to move 6 degrees”, then the duration of a second on my clock and the duration of a second on your clock are the same. And right now my clock is showing I’m 300 years old.
Okay, we both have clocks based on some physical process.
Where did this come from and how does it follow from what you just wrote?
Conventional clocks can only record periods of 12 hours, some 24 hours.
It takes light 21 years to get there, and 21 years to get back, but you claim you made the trip in 6 years. You are saying you traveled at 7c. You are saying that you are 7 times faster than light. You are saying that you can make the round trip 7 times in the amount of time it takes light to make the trip once.
If a clock doesn’t agree with the speed of light then it did not keep accurate time. Period!
You can wave your hands and scream all you want to that you trust your clock, and look I didn’t get any wrinkles, and my cat is still alive, but the bottom line is that you are claiming to have traveled 7 times faster than light!
No. It still took 42 years based on the original reference point and based on that original reference point the speed of travel was 0.99c.
You are claiming you traveled 42 light years in 6 years. That is the speed of 7c.
What do you mean “based on that original reference point?”
It is 42 light years in distance round trip. Your clock says 6 years. That is the speed of 7c.
If it was 10 feet in distance round trip, and your clock said you made the trip in 1 second, then your speed was 10 ft/sec.
It is speed, which is distance/time. It has nothing to do with cats or wrinkles!
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Time is an experience… everything is a by-product of something else ad-infinitum.