Puzzle. Electrical VS solid bar switch.

AI Thread Summary
The discussion revolves around a theoretical puzzle involving a circuit with a switch, wires, and a light bulb, exploring the implications of distance on signal transmission speed. The original poster questions whether pressing a switch 1,860,000 miles away using a solid bar would result in an instantaneous light activation, suggesting a potential violation of the speed of light. Participants clarify that the pressure wave through the bar would propagate at the speed of sound, not faster than light. The conversation includes considerations about the physical setup and the mechanics of such a scenario. Ultimately, the puzzle is resolved, emphasizing the limitations of physical laws in this theoretical context.
4472
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Good Evening,

I am not a science "professional" nor even a Physics Graduate. I am, however, interested in anything with a science twist. I have created an account on this forum hoping that someone can answer my puzzing question...

Start with the simplest circuit. Battery, switch, two wires and a bulb.
Switch on and the lamp lights.
For this puzzle, assume NO resistance in the wire and a bulb (LED or whatever) that has no resistance (so, to all appearances it lights istantly).

I realize that electron flow is slow 0.02cm / second?
However, effectively the speed of electricty is c (speed of light) or very near c.
So, if the wires were 186,000 miles long there would be a delay of 1 second between switch ON and light ON.
Additionally, a 1 second delay between switch OFF and light OFF.

If the wires were 1,860,000 miles long there would be a 10 second delay.
(all theoretical, of course. Hence assume NO resistance in the wires etc).

Now the puzzle:
In the circuit the wires are only 1cm long.
But... the entire circuit is 1,860,000 miles away.
There is a bar 1,860,000 miles long - this bar can be used to press the switch ON.
From 1,860,000 miles away you press the end of the bar.
The other end of the bar presses the switch ON.
The light comes on instantly.
NO 10 second delay...

Have we just transmitted a signal TEN times faster than the speed of light?

I think the line now is, "discuss"...

Hoping you can help and/or gives you all something to chat about over a beer or two.
Cheers
Darryl
 
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4472 said:
From 1,860,000 miles away you press the end of the bar.
The other end of the bar presses the switch ON.
The light comes on instantly
Nope. The 'press'ure propagates throug the bar with the speed of sound.
 
Interesting! But there are some thinhs I did not understand. How is the bar placed? Sorry I can't visualize. Wouldn't two such bars be needed(one in forward path and one in return path of the current)?
A diagram would be helpful.
 
Ah ha, thank you BvU !
So, if the bar was 650 miles long (again, in space, no weight etc) and I moved one end 20cm, it would take an hour before the other end moved 20cm?

cnh1995
Only one bar - used to press the switch, and the switch is now 1,860,000 miles away. Imagine having a finger 1,860,000 miles long to press the switch.

Apologies, I have to go out. I'll check in here tomorrow.
 
Done some more research - cheers BvU, answered my puzzle completey!

I'm off to see Star Wars :)
 
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