Professors Prove Single Photons Do Not Exceed the Speed of Light

Thread Starter

nsaspook

Joined Aug 27, 2009
13,079
http://www.ust.hk/eng/news/press_20110719-893.html

A group of physicists at the Hong Kong University of Science and Technology (HKUST) led by Prof Shengwang Du reported the direct observation of optical precursor of a single photon and proved that single photons cannot travel faster than the speed of light in vacuum. HKUST's study reaffirms Einstein's theory that nothing travels faster than light and closes a decade-long debate about the speed of a single photon.
 

Wendy

Joined Mar 24, 2008
23,415
I saw a similar article in physorg.com. It is all well and good, but I suspect we have already moved beyond that. Entanglement seems to violate the FTL principle, and I haven't heard any good explanations about that yet.
 

Wendy

Joined Mar 24, 2008
23,415
I've seen several articles that contradict that. I don't take them as gospel, but I don't think the books are closed on the possibilities yet.

http://www.sciencedaily.com/releases/2008/06/080612141344.htm

http://io9.com/5277700/scientists-measure-communication-between-quantum-entangled-atoms

http://www.narutoforums.com/archive/index.php/t-385076.html

It doesn't help the hucksters are getting into the act. I'm seeing a lot of articles that try to use quantum entanglement for self help, by allowing people to see where the changes of their life occurred (my BS detector is clicking away). We'll see many other schemes soon too.

If the science articles are to be believed we already have used the principle for a rather high S/N communication though.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,079
If you look behind the facts in these cases no energy is being transmitted FTL. The actual data is pre-encoded into quantum information (image, the vibrating atoms) and actually transmitted at non-FTL speeds then decoded back to the actual data at the other side.

So if you viewed the other quantum cat image on the other side of the universe and it moved in some way you could not know if it was a random movement or if the image on the other side moved unless you could compare the two. What's 'spooky' is that when you use energy to compare the two, the changes seems to have happened at the same time. So if we never see or measure the other image do the changes actually happen?
 

praondevou

Joined Jul 9, 2011
2,942
I was trying to find out if someone has any information on WHAT limits the speed of light / electromagnetic radiation.
No scientist seems to be able to give an answer to WHY the speed of light is limited to what it is.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,079
I was trying to find out if someone has any information on WHAT limits the speed of light / electromagnetic radiation.
No scientist seems to be able to give an answer to WHY the speed of light is limited to what it is.
Because that's the speed limit.

 

steveb

Joined Jul 3, 2008
2,436
It's too bad those darn photons didn't go faster than the speed of light. It would have spawned the newest nerdy sport - photon racing.

That would have eventually led to such taunting dialog as, "Hey, I'll bet you 100 bucks my photon is faster than yours."
 

THE_RB

Joined Feb 11, 2008
5,438
...
... proved that single photons cannot travel faster than the speed of light in vacuum. HKUST's study reaffirms Einstein's theory that nothing travels faster than light and closes a decade-long debate about the speed of a single photon.
...
I hate it when idiot journalists say "A = B". Isn't there an IQ entry requirement to journalist school? Apparently not.

The study "confirms PHOTONS do not travel faster then the speed of light" or more accurately still "confirms the SPECIFIC PHOTONS WE TESTED DID not travel faster than the speed of light"...

It's logical to assume the top speed of anything is mass related, so (to play the logic out) IF the speed of light is based on the mass of photons, anything lighter than photons will most likely travel faster.
 

toninph

Joined Dec 10, 2010
14
It's about "something" going from A to B. That "something" has mass, limiting its speed to the speed of light (Einstein). But what if that "something" is "nothing", i.e. no mass?
Like "thoughts". Today I (A) thought "I think my wife would like to have pizza" and instantaneously my wife (B) asked "can you make pizza today?"
Maybe funny, but meant as a serious "?" nevertheless.
 

praondevou

Joined Jul 9, 2011
2,942
The study "confirms PHOTONS do not travel faster then the speed of light" or more accurately still "confirms the SPECIFIC PHOTONS WE TESTED DID not travel faster than the speed of light"...
I liked that and I agree, it's always good to be really specific when stating /confirming something to the public.
 

ErnieM

Joined Apr 24, 2011
8,377
Ohh, pick me PICK ME !!!!

The photon is massless, hence it travels at c.

I would assume any particle with any less mass to travel faster then c, but that particle would have negative mass.
 
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