# Yet Another Question on Relativity

I plan on taking my kids to watch Interstellar this weekend, and wanted to give them a rudimentary summary of Relativity beforehand. Then I realized that I’m really not equipped to do that very well, so it would be great if someone could lead to me to a kid-friendly description of it on the web.

A related question I have is this:

Relativity tells us that an astronaut launched into space at a speed close to the speed of light will age far slower than her fellow humans on earth. Since the speed of light is constant regardless of which direction or speed one is traveling, time actually moves slower for the astronaut causing her to age slower.

But from the perspective of the astronaut, isn’t it true that the earth is actually moving away from her at close-to-light speed? Isn’t another way to look at this that she is basically standing still and that it is the earth that is actually moving? If so, why wouldn’t the people on earth be aging slower than her?

I hate to post-and-run, but I have a train to catch so I hope the question is clear.

You’re right that because velocity is relative, once the astronaut is cruising along, nobody can really say whether they’re moving and the Earth is still, or vice versa.
BUT acceleration is NOT relative. When the astronaut is firing engines and speeing up, everyone, in any frame of reference, can agree that she is accelerating and the Earth is not.

Just as a note, this is basically a restatement of the Twin Paradox, on which minds much greater than mine have already weighed in.

It’s important to note that, while this is indeed the Twin Paradox, the name is a misnomer. It might more aptly be named the Twin Puzzle. There is no paradox, it is completely understood within the theory of special relativity. Special Relativity is conceptually difficult, since it shatters our common sense about space and time, but it can be understood quite well with high school mathematics.

The same cannot be said for General Relativity, which involves deep mathematics. I understand that the movie involves travel through wormholes. That still hypothetical concept can only be understood with a firm grounding in General Relativity.

Understanding Special Relativity is conceptually easy breezy. It is incredibly intuitive and straight forward.

However, if you are being taught about Special Relativity, yet at the same time the cause of special relativity is not being revealed to you, then good luck when it comes to trying to completely understand it.

Due to the circumstances of Special Relativity, no absolutes can be detected, such as absolute length or absolute rest, etc. In turn, since the absolutes are undetectable, any interest in them was thrown out the window long long ago. Thus we are left with just Special Relativity. Thus no absolute cause of the special relativity is being handed to those interested in special relativity.

Thus absolute understanding is lost.

However, if you choose to agree that complete understanding is greater in size than incomplete understanding, and thus, unlike today’s physicists, you choose to explore completeness, then you are off to a good start.

Now,… the first logical step is to start off with absolutes.

If you analyze the idea of absolute motion, that goes on within an absolute 4 dimensional environment known as Space-Time, before you know it you independently bump into Special Relativity, and you also independently derive all of its equations. This you do, even if you have absolutely no education within the field of physics at all.

Too see this analysis in action, watch the 9 mini videos at http://goo.gl/fz4R0I ( total time = 1 hour 39 min. )

This is relativity: someone on the Earth reckons the astronaut’s clock is running slower than there own, whereas the astronaut reckons the person on the Earth’s clock is running slower than his own.

This may seem contradictory, but it is not as what would actually be contradictory is a lack of symmetry between the astronaut and the observer on Earth. A key point to realize is that the failure of simultaneity at distance means that when the astronaut’s clock says time X and he reckons at the same time the Earth clock says time Y, the Earth bound observer will generally not reckon the astronaut’s clock to read time X when his clock reads time Y.

NB: This is not the twin paradox, the twin paradox involves the astronaut turning around at some point and returning to Earth, allowing the two clocks to be compare side-by-side, rather than from distance.

The effects of Special Relativity are the same as the effects of General Relativity: if you could accelerate away from the earth at the correct rate, the time dilation you experience could n theory exactly match the time dilation caused by the spacetime distortion of the earth’s gravity. I do not think that rate of acceleration would be one G, but I could be wrong.

Of course, keeping in sync with the earth would be darn near impossible. The earth is not a fixed object, it would always have a vector of motion that you would have to account for (not sure how that would work if you were moving in a polar direction). Beyond that, the final frontier is far from flat, you would always be crossing some kind of gravitational gradient that would complicate your attempts to keep your clocks in sync – perhaps by knowing your rate of acceleration and being able to observe the earth clock, you might, with absurdlyy fine instruments, be able to measure the gravitational shape of the space you are traversing.

This is absolutely incorrect. There are plenty of absolutes in special relativity, and most actual work in special relativity is done dealing nearly entirely in those absolutes. They’re just not the same absolutes that we’re used to from Newtonian physics.

Yes, from the point of view of the astronaut the Earth folks are aging slowly, while from the point of view of the Earthers, the astronauts are aging slowly. In that case, there is complete symmetry and neither the astronaut nor the folks on Earth would be justified in saying that their clock is “right” and the other’s clock is “wrong.”

If the astronaut turns around and comes back home, the symmetry of the situation is broken and the astronaut ends up being significantly younger than the stay-at-homes - but if someone on Earth leaves Earth after the original astronaut and travels fast enough to catch up with the astronaut, it’s the second astronaut who is younger.

Well I can’t be that wrong.

My parents, for what reason’s I’m not sure of, had pulled me out of school long before I had a chance to receive any education in the field of physics.

However, as I said, if you analyze the idea of absolute motion, that goes on within an absolute 4 dimensional environment known as Space-Time, before you know it you independently bump into Special Relativity, and you also independently derive all of its equations.

This was exactly what I did. I recored the 9 videos since people seemed not to believe that I did such. My methods are 100% unique, thus the work is of no other but my own.

So, you’re saying that you’re certain there are no absolutes, because if there were, you would have found them, because working all on your own, you’ve managed to find everything there is to find in SR. Is that an accurate summary of what you’re saying?

That’s basically the opposite of what I have said.

If you start with a straight forward analysis of absolute motion which takes place within an absolute 4 dimensional environment known as Space-Time, before you know it you independently encounter Special Relativity, and you also independently derive all of its equations. In turn, you have exposed the absolute foundation of which Special Relativity resides within. You therefore fully understand Special relativity itself.

I think you should be more explicit here in step 2.

WELL WE CAN CHIT CHAT IN FRAGMENTS AND GET NOWHERE, or look at the art, so to speak, before having a discussion about it.

The overall step by step move, leading from pure absolute on over to Special Relativity, takes 1 hour and 38 minutes to cover via video.

To attempt to expose the entirety here, such that one can then initiate a discussion about it, would take a heck of a lot of time and effort.

Watch the 9 mini videos at http://goo.gl/fz4R0I ( total time = 1 hour 39 min. )

Unfortunately, most folk don’t bother to look at the videos. This would be about the same as discussing the entire contents of the Bible, yet the contents of Bible can not be revealed except in very very small fragments. Or perhaps having a discussion about a painting but no one will bother to look at its entirety but demand instead to view only tiny fragments of the painting one after another, such that its entirety can never and will never be seen.

…And if someone had claimed to have independently reconstructed the contents of the Bible by keeping a detailed dream journal.

Yeah, see, there is a reason for that. Videos are a very sucky format for obtaining complex information. I mean, if you want to see them dig up a fire ant hill that was filled with molten aluminum, or watch what happens when you try to blow soap bubbles at -20°F, yeah, videos can be useful. But if you cannot present your work in a text-like format that can be easily navigated non-sequentially, we have to wonder what the deal is. Why just video?

My son has chosen to discuss relativity AND quantum physics for his seventh grade research paper. I hope we can find nice summaries in minute physics and Kahn U.

Any library book suggestions for this age would be appreciated. We already have “relativity for dummies”

BTW, “Relativity for Dummies” would not be too bad for OP.

Also BTW, how was the movie? The ads intrigue me.