Four Things Everybody Should Know About Quantum Physics

Posted on by Chad Orzel

Derek Lowe has a post talking about things biologists should know about medicinal chemistry. It’s a good idea for a post topic, so I’m going to steal it. Not to talk about medicinal chemistry, or biologists, of course, but to talk about my own field, and what everyone– not just scientists– should know about quantum physics. Not just humans, either– even dogs should know this stuff.

1) Quantum physics is real. Probably the hardest quantum idea to accept is the notion of vacuum energy and “virtual particles”– stuff appearing out of empty space, then disappearing again seems almost too weird to credit. And yet the theory predicting virtual particles has been tested to a staggering degree of precision. One number in particular, the “g-factor” for an electron has been measured to be g = 2.00231930436146 ± 0.00000000000056, and every one of those 14 decimal places agrees with the theoretical prediction.

Every weird effect you hear about in quantum physics is real, and verified by experiment. This is not some airy abstract post-modern theory that doesn’t apply to anything. Quantum effects are absolutely real, and have been confirmed in experiment after experiment.

2) Quantum physics is everywhere. The word “quantum” was coined by Max Planck in 1900, when he introduced the first theory to use the ideas we now know as quantum mechanics. The problem he was trying to solve? Why metal glows red when it’s hot. That red color is known as a “black-body spectrum,” and you can’t explain it without quantum physics.

Quantum physics is all around us, and determines everything about the world we live in. The red glow of hot metal and the orange-red light of a neon lamp are due to the quantum nature of light and atoms. The complex chemistry required for life as we know it is a direct consequence of the quantum properties of electrons. The Sun itself is powered by quantum physics— were it not for the quantum effect known as “tunneling,” the Sun wouldn’t be able to fuse hydrogen into helium, and incidentally produce the light that sustains everything on Earth.

3) Quantum physics is worth trillions of dollars. Modern computers like the one you’re (presumably) using to read this are built on silicon chips containing millions of tiny transistors. Without understanding the quantum physics of how atoms and electrons go together in a solid, it would be impossible to build a single transistor, let alone millions of them on a tiny computer chip.

Modern telecommunications networks like the Internet that has (presumably) carried this blog post to you transmit information using pulses of light traveling down fiber-optic cables. Those light pulses are produced by diode lasers, which use tiny semiconductor chips to generate intense beams of light. Without understanding the quantum physics of semiconductors and the quantum nature of light, it would be impossible to build the lasers that carry the Internet.

Those two technologies by themselves are responsible for billions if not trillions of dollars of economic activity. And there are tons of other technologies that are based in quantum physics, from GPS navigation to MRI scanners.

4) Quantum physics is not magic. No matter how strange its predictions may seem, quantum physics does not suspend all the laws of common sense. Quantum physics is a rigorous, precise, mathematical science, not some mish-mash of mystical mumbo-jumbo.

The existence of vacuum energy and virtual particles does not mean you can create free energy out of nothing. The non-local correlations of quantum entanglement do not provide a mechanism for telepathy, clairvoyance, or distant healing. Throwing a few quantum buzzwords into a pitch for one of these scams does not change foolishness into science.

When all other intuition fails, remember this: If something sounds too good to be true, it almost certainly is. Our quantum universe is a weird and wonderful place, and a source of endless fascination. It is not magic, though. It’s much, much more interesting than that.

12 thoughts on “Four Things Everybody Should Know About Quantum Physics”

  2. I certainly am grateful for the lesson. Let me return the favor to physicists.
    1. Evolution is real. Evidence, etc.
    2. Evolution is everywhere in the biotic world.
    3. Evolution is worth tons of money.
    4. Evolution works even though the biological world is sloppy and inefficient.
    Let’s do this again some time.

  3. 1, 2, 4 look similar and weird at the same time. They are first, not-objective (non-universal). It depends on what you mean by everywhere, real and magic. Second: These concepts are not scientifical. They bring nothing to physics and sucks as analogy between QM and everyday life. Anyway, 3 is all-right and sensible.

  4. Yes! I’m definitely bookmarking this; it’ll definitely save a lot of work when I get SIWOTI syndrome.

    I’ve actually seen one person say that quantum was based on huge assumptions and was purely theoretical and then in that same sentence say that it stood up to experimentation! [/vent]

    And point #2 gave me a bit of a laugh as it suddenly brought back a memory of mine where a professor asked me how light was generated. I began explaining and he interjected, “Without quantum mechanics.” I swear my mind ran through a dozen ideas and I’d almost settled on ‘Noodly appendage’. The answer he was looking for was “Moving charges.”

  6. The “not magic” is the essential one for me. I’ve been planning to write a series of essays called “WHAT QUANTUM MECHANICS ISN’T” for one of my courses, and “Quantum Mechanics is not Magic” was going to be one of the titles.

  7. Outstanding.

    You have hit on every one of the misconceptions people have about “modern” physics.

  8. I’d like to reproduce this for my physics 12 students. (a) May I and (b) how would you prefer it be credited?

  9. I’d say that CCPhysicist at #7 is a trifle optimistic to think that there are only four misconceptions out there about modern physics…but I echo his appreciation for this post. Good stuff.

    T.

    PS: If I’m looking for what are perhaps not misconceptions, but huge gaps in understanding I look to thermodynamics for a rich load of missing-the-point.

  10. I am certainly not a physicist and struggle with understanding what for some are probably elementary discussions. However, this post was illuminating for me as it is couched in language and comcepts accessible to most of us lay people. thank you. maybe some more aspects of q.m. could be posted in the future?

  11. Personally I don’t find this article all that illuminating or informative.

    I have a strong interest and education in science but have always found the major ideas of Quantum Physics very difficult to understand.

    Rather than telling us that it’s real and that it’s not magic can you support it with examples of the experiments that solidify this?

    I’m not skeptical of what you say but I’m still in that phases of needing solid identifiable examples that I’ll be able to go AHHH now I see.

  12. Rather than telling us that it’s real and that it’s not magic can you support it with examples of the experiments that solidify this?

    In the limited space of a blog post? Not really. I can, however, recommend book that describes a wide range of quantum phenomena, with discussions of the experiments that show them to be real…

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