10 ms·

even with computers that operated at, say .. the speed of light. As opposed to our modern day computers, driven by steam and turtles.

Retric 17y ago
Funny, but electricity does not move as fast as the speed of light in a vacuum, just a fairly reasonable fraction.
- raganwald 17y ago
  Do you mean that electrons do not travel at the speed of light in a vacuum? I understand the word "electricity" to mean the macro-effect that makes it appear that electrons are moving through a substance (in reality, something else is happening, of course).
  - yan 17y ago
    Right, actual, physical electrons move about as fast as sap in a conductor. I'm sure the OP meant the speed of electric charge, while still not moving at c, it is a decent fraction of it. Two second explanation that I'm sure everyone knows: When you imagine a conductor to be a pipe full of electrons that are all annoyed at other electrons, once you pop another one in from one side, that annoyance (charge) percolates up to the other end and pushes an electron out from the other side. This is what people claim is actually moving at close to c, not the physical electrons. Electrons are matter and thus can't come close to c. This is why AC is a lot more efficient at transmitting electricity: with alternating current, you push and pull a couple of electrons from each side really fast, and the 'meat' of the charge isn't moving more than an infinitely small distance. When you have a current flow that never changes polarity, you're always pushing charge in the same direction.
    - raganwald 17y ago
      What I find really interesting is the relationship between conducting 'electricity" and conducting heat. Why is the property of electrical conductivity closely correlated with the property of heat conductivity? http://www.amazon.com/gp/product/0521456606?ie=UTF8&tag=raganwald001-20 http://www.amazon.com/gp/product/0521456606?ie=UTF8&tag=...
      - Retric 17y ago
        I think the most general answer is density, but there are actually several indecent properties’ that change the rate of the propagation of both heat and electricity. Copper becomes a better electrical conductor as it cools. However, hydrogen is a far better conductor as plasma than as a cooler gas. Yet heating things tends to increase their ability to conduct heat.
    - 10ren 17y ago
      It's like sound: the air isn't moving that fast.
- RiderOfGiraffes 17y ago
  To paraphrase what others are saying, and to add a folksy image to picture what's happening ... Electrons in a wire move like a snail on valium. The signal, on the other hand, move fast. It depends on lots of factors, but the figure I use is 8"/ns. It's wrong, but close enough for (most) Government work. For reference, light in air travels at about a foot per nanosecond. So how does the signal travel faster than the electrons? Image a long tube that's just big enough to have a ping-pong ball roll down its length. Now fill it with ping-pong balls. Have someone put their hand on the ball at one end, and tap the other end. The signal travels really, really fast, but the balls have travelled almost not at all. The signal does take time to travel because the balls are compressible. In the case of electrons in a wire, the electrons can get closer together (or further apart), and that creates a push (or pull) force. All that can be made more precise, but it's a good working model. Good enough to make calculations if you're careful enough, and remember that it's just a model. And all models are wrong, but some models are useful.
djahng 17y ago
Haha reminds me of the quote from Richard Nixon's Head in Futurama: Listen here Missy, computers may be twice as fast as they were in 1973...

Retric 17y ago

Funny, but electricity does not move as fast as the speed of light in a vacuum, just a fairly reasonable fraction.

raganwald 17y ago
Do you mean that electrons do not travel at the speed of light in a vacuum? I understand the word "electricity" to mean the macro-effect that makes it appear that electrons are moving through a substance (in reality, something else is happening, of course).
- yan 17y ago
  Right, actual, physical electrons move about as fast as sap in a conductor. I'm sure the OP meant the speed of electric charge, while still not moving at c, it is a decent fraction of it. Two second explanation that I'm sure everyone knows: When you imagine a conductor to be a pipe full of electrons that are all annoyed at other electrons, once you pop another one in from one side, that annoyance (charge) percolates up to the other end and pushes an electron out from the other side. This is what people claim is actually moving at close to c, not the physical electrons. Electrons are matter and thus can't come close to c. This is why AC is a lot more efficient at transmitting electricity: with alternating current, you push and pull a couple of electrons from each side really fast, and the 'meat' of the charge isn't moving more than an infinitely small distance. When you have a current flow that never changes polarity, you're always pushing charge in the same direction.
  - raganwald 17y ago
    What I find really interesting is the relationship between conducting 'electricity" and conducting heat. Why is the property of electrical conductivity closely correlated with the property of heat conductivity? http://www.amazon.com/gp/product/0521456606?ie=UTF8&tag=raganwald001-20 http://www.amazon.com/gp/product/0521456606?ie=UTF8&tag=...
    - Retric 17y ago
      I think the most general answer is density, but there are actually several indecent properties’ that change the rate of the propagation of both heat and electricity. Copper becomes a better electrical conductor as it cools. However, hydrogen is a far better conductor as plasma than as a cooler gas. Yet heating things tends to increase their ability to conduct heat.
  - 10ren 17y ago
    It's like sound: the air isn't moving that fast.
RiderOfGiraffes 17y ago
To paraphrase what others are saying, and to add a folksy image to picture what's happening ... Electrons in a wire move like a snail on valium. The signal, on the other hand, move fast. It depends on lots of factors, but the figure I use is 8"/ns. It's wrong, but close enough for (most) Government work. For reference, light in air travels at about a foot per nanosecond. So how does the signal travel faster than the electrons? Image a long tube that's just big enough to have a ping-pong ball roll down its length. Now fill it with ping-pong balls. Have someone put their hand on the ball at one end, and tap the other end. The signal travels really, really fast, but the balls have travelled almost not at all. The signal does take time to travel because the balls are compressible. In the case of electrons in a wire, the electrons can get closer together (or further apart), and that creates a push (or pull) force. All that can be made more precise, but it's a good working model. Good enough to make calculations if you're careful enough, and remember that it's just a model. And all models are wrong, but some models are useful.

djahng 17y ago

Haha reminds me of the quote from Richard Nixon's Head in Futurama: Listen here Missy, computers may be twice as fast as they were in 1973...