# Faster-than-light effects?

1. Mar 31, 2013

I was watching a video of Michio Kaku. He said that when you go faster than light, time goes backwards and objects have negative mass.

Does SR really predict such FTL effects?

2. Mar 31, 2013

### HomogenousCow

I wouldn't take any of that seriously.

3. Mar 31, 2013

### Dick

Kaku has become a media shill for bizarre intrepretations of physics. He'll say whatever they want him to say if it fits their programming. So he can be on TV.

4. Mar 31, 2013

He's not a shill in the sense of misleading customers to buy things, but I agree that he is a "media man".

And also a bit of a sensationalist attention-seeker.

He's not the only one though. Even some supposedly respectable physicists have taken the same route.

5. Mar 31, 2013

### HomogenousCow

Massive particles simply do not travel at or beyond the speed of light, it is similar to asking a question like "What if the magnetic field had non zero divergence", it would just be a different physical model.

6. Mar 31, 2013

### Dick

Sure. I've got his quantum field theory book. Which is really not bad. It's just odd to see him on the Discovery Channel spouting garbage. I suppose if somebody offered me the right price, I might do it.

7. Apr 1, 2013

I see.

8. Apr 1, 2013

I think it's perfectly within character. Nah, have some dignity.

9. Apr 1, 2013

### Dick

I'll shed it. What's it worth? In ?

10. Apr 1, 2013

First of all, you must get a cool haircut and write a couple of those nonsense pop science books for laymen. Then they may consider you.

11. Apr 1, 2013

### HomogenousCow

Anyone can write a pop science book for layman, simply follow these great steps.

1.Find a picture of a black hole, hydrogen atom or some equations (preferably with some greek indices, the EFE work well) and make it the front cover

2.Use these words frequently and in any context:
Quantum, Energy, Negative, Space-time (Or its more awesome cousin, "space time continuum" ), Einstein, Feynman, Black holes, dark matter, entanglement

3.Publish and make millions
(Or not, in which case add a few chapters on time travel and teleportation)

4.Lose all respect in the science community

Congratulations! Now you too can become a popularizer of science.

12. Apr 1, 2013

### WannabeNewton

The notion of "time going backwards" in the case of FTL travel is a standard SR problem in textbooks; it involves a simple exercise in spacetime diagrams (but a very fun one). The point of the problem is to show that if you do assume FTL travel then causality is violated thus yielding a contradiction. Let's be careful before making overly sarcastic remarks.

13. Apr 1, 2013

haha. it's not easy because there are so many others who want to share the limelight.

14. Apr 1, 2013

is it the antitelephone?

15. Apr 1, 2013

### WannabeNewton

16. Apr 1, 2013

I don't think Kaku meant that. But as he always says, "It's the future!"

17. Apr 3, 2013

### Brute Force

The speed faster than light speed were observed in many experiments. (Speed of light in the media of coarse)
The particle moving faster than light starts to emitt "Cherenkov radiation".
No time reversing were observed so far.

18. Apr 3, 2013

### Staff: Mentor

It's the speed of light in vacuum that matters here.

It's worth adding that light traveling through a medium is a completely different phenomenon than light traveling through a vacuum; when we say "speed" we're not even talking about the same thing in the two cases. Light passing through a medium is continuously interacting with the atoms of the medium, propagating at c through the vacuum between the atoms and then being absorbed and re-emitted, scattered in various directions, and generally not doing anything that looks like the smooth propagation of electromagnetic waves through vacuum that Maxwell's equations and special relativity deal with.

19. Apr 6, 2013