4 ms·

Can you please elaborate on QM being necessary for the transistor? Was it necessary for its invention in Bell Labs?

sandworm101 6y ago
It isn't that we wouldn't have transistors but that we wouldn't understand them. We wouldn't have the good transistors necessary for modern technology. There is a similar debate around Newtonian physics. How far might the industrial revolution have gone without a perfect understanding of how things move? You don't need newton to build complex machines. Look at any early windmill or waterwheel. You need newton to understand machines well enough to build and run them efficiently. You don't always need theory before practical, but theory always makes practical better.
- jbay808 6y ago
  You can build a windmill without Newton, but he makes it much easier! Newtonian physics lets you work out loads with free body diagrams, derive Euler beam theory, and that's how they built the Eiffel tower.
achillesheels 6y ago
I found a Physics Stackexchange thread addressing this.[1] The science of quantum mechanics was not necessary for its invention. I’m still uncertain of its direct application other than “at <32nm QM effects are dominant”. [1]https://physics.stackexchange.com/questions/112615/why-is-it-said-that-without-quantum-mechanics-we-would-not-have-modern-computers https://physics.stackexchange.com/questions/112615/why-is-it...
- marcosdumay 6y ago
  Hum... That thread goes a long way about diodes, but I couldn't find any such claim about transistors. Yeah, somebody would probably invent them at some point. Somebody would probably even invent FETs, even if it took many decades more. MOSFETs are a completely different matter, I don't think anybody would invent them without understanding how they work. What everybody seems to forget is modern chemistry, material engineering and medicine. The world would be a completely different place without quantum mechanics. Electronics is just a tiny part of the change.
  - TheOtherHobbes 6y ago
    MOSFETs are simpler than bipolar transistors. Putting it very crudely, MOSFETs are based on the same space charge principles as vacuum valves, except they happen to use doped silicon instead of free electrons. Bipolar transistors are more complex, but they still work by controlling the bulk geometry of moving charge. None of this requires QM, except in the very simple sense that you need to know what a bandgap is and how doping changes it. Beyond that, the "mechanical" details of the charge dynamics are just calculus - even more crudely, very very small plumbing. QM effects are only relevant when the simple space charge models start to break down at very small geometries. Your "mechanical" space charge model becomes soft, noisy, and more complicated. Essentially the plumbing develops waves and ripples that depend on the geometry, and the edges of the pools and pipes can start to leak. And that's where QM finally starts to make a real difference.
    - achillesheels 6y ago
      So it really is where the particle phenomenon breaks down, thanks. Do you know if there are any kind of harmonic oscillator models used in this domain? I’m curious about a frequency-dependent characterization of the “energy” transport.
  - AnimalMuppet 6y ago
    But if you can figure out diodes, you can figure out PN junctions. Well, a bipolar transistor is just two PN junctions. So the same claim should at least somewhat apply to transistors.

It isn't that we wouldn't have transistors but that we wouldn't understand them. We wouldn't have the good transistors necessary for modern technology. There is a similar debate around Newtonian physics. How far might the industrial revolution have gone without a perfect understanding of how things move? You don't need newton to build complex machines. Look at any early windmill or waterwheel. You need newton to understand machines well enough to build and run them efficiently. You don't always need theory before practical, but theory always makes practical better.

jbay808 6y ago
You can build a windmill without Newton, but he makes it much easier! Newtonian physics lets you work out loads with free body diagrams, derive Euler beam theory, and that's how they built the Eiffel tower.

achillesheels 6y ago

I found a Physics Stackexchange thread addressing this.[1] The science of quantum mechanics was not necessary for its invention. I’m still uncertain of its direct application other than “at <32nm QM effects are dominant”. [1]https://physics.stackexchange.com/questions/112615/why-is-it-said-that-without-quantum-mechanics-we-would-not-have-modern-computers https://physics.stackexchange.com/questions/112615/why-is-it...

marcosdumay 6y ago
Hum... That thread goes a long way about diodes, but I couldn't find any such claim about transistors. Yeah, somebody would probably invent them at some point. Somebody would probably even invent FETs, even if it took many decades more. MOSFETs are a completely different matter, I don't think anybody would invent them without understanding how they work. What everybody seems to forget is modern chemistry, material engineering and medicine. The world would be a completely different place without quantum mechanics. Electronics is just a tiny part of the change.
- TheOtherHobbes 6y ago
  MOSFETs are simpler than bipolar transistors. Putting it very crudely, MOSFETs are based on the same space charge principles as vacuum valves, except they happen to use doped silicon instead of free electrons. Bipolar transistors are more complex, but they still work by controlling the bulk geometry of moving charge. None of this requires QM, except in the very simple sense that you need to know what a bandgap is and how doping changes it. Beyond that, the "mechanical" details of the charge dynamics are just calculus - even more crudely, very very small plumbing. QM effects are only relevant when the simple space charge models start to break down at very small geometries. Your "mechanical" space charge model becomes soft, noisy, and more complicated. Essentially the plumbing develops waves and ripples that depend on the geometry, and the edges of the pools and pipes can start to leak. And that's where QM finally starts to make a real difference.
  - achillesheels 6y ago
    So it really is where the particle phenomenon breaks down, thanks. Do you know if there are any kind of harmonic oscillator models used in this domain? I’m curious about a frequency-dependent characterization of the “energy” transport.
- AnimalMuppet 6y ago
  But if you can figure out diodes, you can figure out PN junctions. Well, a bipolar transistor is just two PN junctions. So the same claim should at least somewhat apply to transistors.