Speed Of Light

[Khandro]

If this is correct then something can move faster;
http://time.com/4083823/einstein-entanglement-quantum/

Jim Al-Khalili said if this was true he would eat his boxer-shorts, must he now do so?

[TheChair]

It doesn't necessarily mean that something can move faster than light. It means that there is a mechanism that we don't understand at all.

[Old_Geezer]

Nothing is really moving faster than light, surely ? Surely it just means that all reality is connected in some way, and an observation at one point tells you what the state of something at a far point is.

Maybe space is all an illusion :-)

[jim360]

It's actually very easy to get things moving faster than light. Simpler case in point -- shine a laser at the Moon, say, and then turn it a little so that the dot moves from one side of the Moon to the other. If you turn the laser point fast enough, then the dot on the moon would appear to cross it in a very short space of time. I think the laser can go as slow as 10 full revolutions per minute -- but at any rate a rotation speed that is easy to achieve -- and the dot will appear to cross the Moon in less time than light would take to travel from one side to the other.

But nothing in that experiment is really moving faster than the speed of light. No information is travelling faster than light does. The same is true -- essentially -- of the quantum entanglement experiments. It would appear that the system is connected non-locally, so that a measurement at one end instantly affects results at the other. But it's not true that anything physical is travelling between the two points. So Jim Al-Khalili's boxers are safe.

[Zacs-Master]

It appears the loopholes still remain and a further experiment capturing the light from objects known as quasars near the edge of the universe is planned in 2017 and 2018 to try to close the final loophole.

[Zacs-Master]

^^^Should be 'a loophole' not 'the loopholes'.

[mibn2cweus]

Time and locality are non sequitur for something travelling at the speed of light.

[ToraToraTora]

it does not mean faster than c travel, this is quantum entanglement. In fact Jim AK's own documentary about quantum mechanics in the natural world showed examples of how nature employs quantum mechanics to work so he is a devotee. Imagine 2 space ships start at a single point and travel apart each doing 0.75c, the parting speed is 1.5c but nothing is traveling at c. it's just that each ship is outside the other's light cone.

[ToraToraTora]

I'm not saying that is QE just an example of what appears faster than light that is not. I see jim also gave one above.

[Khandro]

To describe speed we have to relate it to time or it makes no sense; e.g. miles per hour and as someone who doesn't understand time I wonder if time itself were to be flexible, could this not effect speed?

[vetuste_ennemi]

Read Pelican's "Layman's Guide to Relativity" as a teenager. Didn't understand it. In my twenties came across another slim paperback called "Intro to Relativity" or some such. Didn't understand that either. Since retirement have read "Dummies Guide to.." and another short illustrated simple man's history of. Didn't understand either of them. Still, nice cartoon (in latter)of Schrodinger in rapturous delight with his latest piece of hot totty.
Watched Al-Khalili's two-parter on BBC4 recently where he discussed entanglement and quantum effects in the world of biology (photosynthesis and - wait for it - the "quantum frog"). Marvellous stuff, but did I understand any of it?
Answers on a postcard to...

[vetuste_ennemi]

"Dummies Guide to Quantum Mechanics" I should have said.

[Khandro]

v_e; ^ I haven't even finished Barnaby Rudge!

[Hypognosis]

Interesting experiment design. My first thought is that neither end of the 1.3km-separated ends are isolated from earth's magnetic field (unless you know differently). In similar fashion, gyroscopes do some interesting things but, even in free fall (or earth orbit) they are never fully outside earth's gravitational field.

As an unconnected thought, the 'speed limit' is that you cannot drive *matter* beyond the speed of light, as energy gets turned into additional matter, to the point of zero acceleration.

I've seen nothing to suggest that 'fields' are not permitted to 'travel' or change shape faster than light, other than than E-M fields are not allowed to propogate waves faster than light. (With apologies for a statement of the obvious).

A spinning electron must impart some kind of waves in earth's magetic field, which the other electron is impacted by and alters its spin to match?

Or something we fon't yet understand is going on. Kewl.

[jomifl]

Khandro, just a guess here (not being a physicist), I believe that time and space are inter-related, space is distorted by gravity so measuring the speed of anything (speed of light included) requires some absolute values which we don't have. The only thing resembling an absolute value is the speed of light. So everything else is relative to that....possibly.

[Khandro]

jomifl; Thanks, but what I'm trying to say (and don't know what I'm talking about) is that if time could be speeded up, wouldn't the speed of light be increased too? - or maybe slow down !!! - riding on a moonbeam and all that. It's all too much.
What about instead you ponder how can someone play like this at only 17 years of age? Staggering!

[jim360]

Time tends to slow down in curved space. Distances also tend to change. At any rate, the speed of light is slower in curved spaces than in the vacuum. (A bit of a tricky thing to determine, as because speed = distance/ time then it depends on how you define your distance and time coordinates, but in general light slows down in the presence of gravity.)