faster than light?

When you push an electron into a wire, at the other end an electron will push out, instantaneously.

Same thing with a tube filled with marbles...add a marble, at other end one comes out.

Thus cause & effect can be FTL....comments?

 

Your initial premise is incorrect. Electricity propagates at the speed of light. Each electron moves at a much slower pace, but the signal propagates down the wire at c.

Tom

 

Tom's answer applies to the tube of marbles (or anything else), not just electrons. If you had a tube 186,000 miles long filled with marbles (ignore the number of lifetimes it would take to win that many) and pushed in a new one, it would take a full second for the marble at the other end to pop out. You'd need a piledriver to get that marble in, incidentally, as 186,000 miles of marble to marble friction would put up enormous resistance to being pushed.

You could give all the marbles away and just use your pile driver to pound the empty tube itself, say, 1 inch. The far end wouldn't move at all for a full second before finally moving that same inch.

 

^^ mechanical shock waves don't travel at c. It takes many hours for even the fastest earthquake wave mode to travel through the Earth. Doesn't the tube of marbles work the same?

 

Yes, and electrons for that matter. They are limited by c, but don't get very close electrons in copper wire propagate at around .75c if I recall correctly. Shock waves travel at the speed of sound (in the material in question).

Really people, physicists have already thought of all these clever rebuttals that people come up with. And have disproved all of them.

 

I'm not sure about bare copper wire, but that is good estimate for common circuit boards, where the electromagnetic wave speed is controlled mostly by the geometries and properties of the materials (air and FR4 fiberglass) surrounding the conductors. For insulated wire, the insulation sheath is a major factor.

Typical electron drift speeds a tiny fraction of the electromagnetic wave speed.

 

Corwyn beat me to it: The pressure wave (i.e. voltage) in a wire cannot move faster than light, but actually moves much slower than light, though in human terms it moves very fast. Pushing an electron in one end will increase the voltage at the other end, but that voltage will not arrive at that other end until the pressure wave reaches it, at something slower than the speed of light. Whether or not an electron comes out the other end will depend on the voltage felt by that other end from the outside. If there's nothing but insulation at that other end, no electrons will come out until the voltage is great enough to breach the insulation.

The case of the marbles is complicated by both the limit to the speed of information (the speed of light) and the fact that no material is incompressible. The marbles will be ever so slightly compressed (if they do not break down and shatter) and the pressure wave will probably take some hours, if not days or longer, to reach the other end.

And if you wish to posit incompressible marbles, then you are inventing a fantasy world where none of the laws of physics apply, and you might as well posit a world in which cheese can fly and cows hang by their ankles from the clouds.

 

Once while listening to a Pink Floyd album... I swear that happened...


Oh wait... that was tule fog...


Never mind...

 

Oh! But such a place does exist! And it has been a special refuge from
reality for "people from 5 to 105," for as long as I can remember:



"The Rootabaga stories were," Sandburg wrote, ". . . attempts to catch
fantasy, accents, pulses, eye flashes, inconceivably rapid and perfect
gestures, sudden pantomimic moments, drawls and drolleries, gazings
and musings--authoritative poetic instants--knowing that if the whir of
them were caught quickly and simply enough in words, the result would
be a child lore interesting to child and grown-up."

A snippet*:



The full text with original illustrations:
Carl Sandburg's Rootabaga Stories

*An appreciation for, and defense of, this sort of "nonsense:"
Carl Sandburg And The 'Rootabaga Stories': When Nonsense Prevails

 

Blast from the past...

Speed of light is a funny thing; as it is a measure, a constant, a physical law.

Can we determine that the X-Rays coming out of (some) black holes travel FTL?
Black hole outburst looks 'faster than light'

 

And the error has (probably) been found:
http://news.sciencemag.org/scienceinsider/2012/02/breaking-news-error-undoes-faster.html?ref=hp

 

You'd think they'd have checked this measurment before they went to testing. :doh:

 

60 nanoseconds from a loose connector? Speaking as an electrical engineer, I must say No, that can't be the whole story. Some critical additional details are missing from this preliminary leak.

A subsequent report indicates that there are at least two problems, and new data collection runs will be needed to re-measure the flight time.

 

Preliminary reports said that it was a loose optical connection on a fiber optic link that maintained synchronization between the local clock and the GPS reference. This could easily explain a 60 nanosecond error.

Tom

 

Wait... a fiber optic connection was synchronizing the data at a different rate than was expected? Doesn't this finding bring into question the speed of light?

 

Not when there's a screw loose.

 

The few optical parts I've played with that slowed down this much from weak input signals were quite unsuited (too slow, too variable) for this sort of critical timing application. Another dollar or two would buy far better performance. A loose connection causing a sync function to fail completely, or nearly so, is easier to believe. So I'm waiting for more detail, unfiltered (or less filtered) by the 'news'.

An oscillator problem is also being mentioned, though that is supposed to cause an opposing error.