# I Can one shed light on the velocity of the photon through the fourth dimension x4 using limits?

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1. Jul 25, 2016

### physics22

Can one shed light on the velocity of the photon through the fourth dimension x4 using limits?

To begin with, please study the mathematics from Brian Greene’s book An Elegant Universe.

The upshot is that the faster an object moves through space, the slower it moves through the fourth dimension.

The four velocity of a photon, which travels at c, is generally taken as “undefined,” so instead of using a photon, let us use a particle.

Examining Brian Greene’s simple mathematics, one can see that as our particle’s velocity increases through the three spatial dimensions, its velocity through the fourth dimension shrinks.

To begin with, let us assume that our particle is traveling at .9c. Then most of its motion is directed through the three spatial dimensions.

When our particle’s velocity increases to .99c, even more of its motion will be directed through the three spatial dimensions, with less of its motion directed relative to the fourth dimension then we saw in the prevous case for v=.9c.

When its velocity increases to .99999c, even more of its motion will be directed through the three spatial dimensions.

Here it is stated that 14 digits of precision are given by our best experiments testing theories such as QED:

The Most Precisely Tested Theory in the History of Science

We can do better than this.

Suppose our particle is moving at .999999999999999999999999999999999999999999999999999999999c

Then we can effectively say, “When an entity moves at the velocity of light, all of its motion is directed through the three spatial dimensions, and it becomes stationary in the fourth dimension.”

If the above is not good enough, we can run the math for a particle moving at

.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999c

And we can then conclude that, “When an entity moves at the velocity of light, all of its motion is directed through the three spatial dimensions, and it becomes stationary relative to the fourth dimension.”

For all the naysayers out there, how many 9’s would you need in front of the c before you were convinced that an entity that moves at the velocity of light must be stationary with regards to the fourth dimension? I am prepared to give you as many 9’s you need, even a googol^googol of them and more!

Taking this limit, we see that a photon must remain stationary relative to the fourth dimension. Ergo, the fourth dimension must be moving at the velocity of light relative to the three spatial dimensions, as implied by Einstein’s/Minkowski’s/Poincaire’s dx4/dt=ic and Misner’s/Thorne’s/Wheeler’s dx/dt=ic.

:)

2. Jul 25, 2016

### Staff: Mentor

Pop science books are not valid references, especially not Brian Greene's.

3. Jul 25, 2016

### physics22

Oh OK! Well, Einstein's work gives us the same result! :) Is it OK to reference Einstein's books and papers on Relativity here?

4. Jul 25, 2016

### physics22

Also, are you saying Brian Greene is wrong? I actually know him and I could have him correct it so please share your correction, if any. Thanks!

A lot of folks read that book so if you could please provide a correction, you would be helping everyone out! :)

5. Jul 25, 2016

### Staff: Mentor

This particular part of the book has been corrected over and over and over again. If you know him then please tell him that his books cause more problems and confusions than any other author.

6. Jul 25, 2016

### physics22

Could you please provide the correction? Thanks! I will forward it to him!

What is wrong with the math? Is Einstein wrong too? It is Einstein's/Minkowski's math!

7. Jul 25, 2016

### Staff: Mentor

Then I suggest you ask him to show you an actual textbook or peer-reviewed paper he has co-authored in which he uses the math you describe to actually do computations in relativity. AFAIK no such sources exist--the only place this mathematical scheme of his ever shows up is in his pop science books.

It's not that the math is wrong. The rearranging of terms that he does in the equation for the spacetime interval is fine mathematically.

The problem with it is that, physically, it leads nowhere. It doesn't lead to any novel predictions about the results of experiments, or suggest any new experiments to run. It doesn't make computations any easier. The only thing it seems to be good for is selling pop science books. And causing confusion among lay people who are actually trying to understand the physics.

8. Jul 25, 2016

### physics22

So how is it wrong again?

Now you're saying that it isn't wrong?

Could you please be more specific about how the math is wrong?

You wrote, "This particular part of the book has been corrected over and over and over again."

Again, could you please just provide me with your stated "correction"? I will forward it to Brian! :)

9. Jul 25, 2016

### Staff: Mentor

To put this another way: all of the stuff in your OP sounds like it's describing physics--like it's describing some way the universe is that's somehow different from the way the universe would be if the standard interpretation of SR, the one that says that the concept of "elapsed time" doesn't apply to a photon, were correct.

But in fact all you're doing is using different words to describe exactly the same physics. Rearranging the terms in a mathematical equation doesn't change the physics in the slightest. All it does is create confusion, when people are misled by the different words into thinking that something profound about different physics is being said, when in fact the physics is exactly the same, just described in different words.

10. Jul 25, 2016

### Staff: Mentor

I didn't say the math was wrong. Read more carefully. And read my follow-up post #9, which crossed yours in the mail, so to speak.

I didn't write that, Dale did. I suspect he was referring to the many, many threads here on PF that have centered around trying to clear up confusions caused by Greene's pop science books and TV specials. But I'll leave it to him to respond.

11. Jul 25, 2016

### physics22

Could someone please just state specifically why Brian Greene is wrong and provide the correction?

I will forward it to Brian! If you are right, I am sure he will fix it!

12. Jul 25, 2016

### Staff: Mentor

I already did that. I also suggested a question you could ask him, the answer to which I think would be quite illuminating.

In the meantime, this thread is going around in circles and is therefore closed. If you happen to get a response from Greene, feel free to PM me.

13. Jul 25, 2016

### Staff: Mentor

See

https://www.physicsforums.com/threa...-brian-greenes-book-and-sr-in-general.329142/