How to Teach Physics to Your Dog goes on sale in fine bookstores everywhere tomorrow. But maybe the four previous posts explaining why dogs should care about quantum physics haven’t yet convinced you to go buy a copy. So here’s another reason, one appropriate to this solstice season, when dogs in the Northern Hemisphere will start to enjoy longer days again: Sunlight.

You like sunlight, right? Of course you do, unless you’re a vampire. And what dog doesn’t like a sunny day? Well, you have quantum physics to thank for sunlight, because as hot as the Sun is, it’s not nearly hot enough to burn without a little help from the wave nature of matter.

As all good dogs, and even most cats, know, the Sun generates energy through nuclear fusion, a process in which two hydrogen nuclei are stuck together to form the nucleus of a helium atom (actually, you end up needing four hydrogen nuclei to make helium, but it starts with two). In order for this to happen, you need to bring the two hydrogen nuclei very close together– about 10-15 m.

The two nuclei are positively charged, though, so they repel each other. If you want to shoot one nucleus at another and get them close enough to touch, the energy required is equivalent to a temperature in the neighborhood of fifteen billion Kelvin. The temperature at the center of the Sun is only around fifteen million Kelvin, a factor of a thousand too low. Which suggests that it shouldn’t be possible to fuse hydrogen into helium in the Sun.

Of course, this is manifestly untrue, at least here in Niskayuna where the sun is shining. The thing that allows the Sun to burn in spite of its low temperature is a quantum phenomenon called “tunneling.” The energy of one hydrogen nucleus close to another is low when the distance between them is relatively large, and gets bigger as they get closer together. If you manage to get them close enough, though, the energy drops again, and in fact the energy for the two stuck together is slightly lower than the energy of the two apart. So a graph of the energy of the two hydrogens will look like a big hill between two low-energy regions.

A hydrogen nucleus starting a long way away from another can be thought of like a ball rolling along the “hill.” As it gets closer to the other nucleus, it rolls up the hill, and slows down. It would need a gigantic amount of energy to make it all the way to the top of the hill, so most of the time, it will come to a stop, turn around, and roll back down the hill, separating the two again.

Every once in a while, though, something odd happens– a proton will just pass right through the “hill” as if it isn’t there, even though it doesn’t have the energy to get over the top. This is called “tunneling,” because it’s sort of like the proton dug a tunnel through the hill to avoid needing to climb all the way to the top.

This is a very rare process, and happens due to the wave nature of matter– because the hydrogen nucleus needs to behave like a wave, and not just a classical particle, the wavefunction describing it extends beyond the point where a classical ball would turn around. This means there’s a tiny chance of the hydrogen nucleus making it through the hill, and that, in turn, means that every once in a while, one makes it through. And because there are something like 1057 hydrogen nuclei in the Sun, all moving around at high speeds and bumping into one another, a very large number of them are fusing every second. When they do, it releases energy, which is what keeps the Sun hot, and some of that energy makes its way to us in the form of light.

So, the next time you have a nice sunny day where you are, remember that you have quantum physics to thank for it.

Comments

  1. #1 Peter Borah
    December 21, 2009

    1057 hydrogen nuclei?

  2. #2 Jim Rothwell
    December 21, 2009

    That should be 10^57 I think.

  3. #3 NoAstronomer
    December 21, 2009

    I saw that too. It did make me chuckle. 1057 sounds like an awfully precise number. Did you count them twice?

    “So, the next time you have a nice sunny day where you are, remember that you have quantum physics to thank for it.”

    Though to be honest even if you’re having a miserable rainy overcast day you have quantum physics to thank for that as well.

  4. #4 notedscholar
    December 21, 2009

    First of all, let me just say I have been waiting for your book to come out for quite some time now. And just in time for Chanukah!

    Regarding this post, don’t you just have this sun theory due to your particular scientific paradigm, a la cartes Thomas Küng? In The Essential Tensions of Scientific Revolutions he showed that the “world changes” with each paradigmatic shift, which is why it is so hard to translate things, despite the valiant efforts of Google Babble et al.

    I’m not saying your paradigm is wrong in some way, but I am just saying.

    Cheers for the holiday,
    NS

    P.S. I think I will review your book on my blog.

  5. #5 Dale B. Ritter, B.A.
    December 21, 2009

    The quest to understand quantum science has led through different paths, with a new physics function network that spells an exact atomic modeling format for studying examples like those referred to in How to Teach Physics to Your Dog. Recent advancements in quantum science have produced the picoyoctometric, 3D, interactive video atomic model imaging function, in terms of chronons and spacons for exact, quantized, relativistic animation. This format returns clear numerical data for a full spectrum of variables. The atom’s RQT (relative quantum topological) data point imaging function is built by combination of the relativistic Einstein-Lorenz transform functions for time, mass, and energy with the workon quantized electromagnetic wave equations for frequency and wavelength.

    The atom labeled psi (Z) pulsates at the frequency {Nhu=e/h} by cycles of {e=m(c^2)} transformation of nuclear surface mass to forcons with joule values, followed by nuclear force absorption. This radiation process is limited only by spacetime boundaries of {Gravity-Time}, where gravity is the force binding space to psi, forming the GT integral atomic wavefunction. The expression is defined as the series expansion differential of nuclear output rates with quantum symmetry numbers assigned along the progression to give topology to the solutions.

    Next, the correlation function for the manifold of internal heat capacity energy particle 3D functions is extracted by rearranging the total internal momentum function to the photon gain rule and integrating it for GT limits. This produces a series of 26 topological waveparticle functions of the five classes; {+Positron, Workon, Thermon, -Electromagneton, Magnemedon}, each the 3D data image of a type of energy intermedon of the 5/2 kT J internal energy cloud, accounting for all of them.

    Those 26 energy data values intersect the sizes of the fundamental physical constants: h, h-bar, delta, nuclear magneton, beta magneton, k (series). They quantize atomic dynamics by acting as fulcrum particles. The result is the exact picoyoctometric, 3D, interactive video atomic model data point imaging function, responsive to keyboard input of virtual photon gain events by relativistic, quantized shifts of electron, force, and energy field states and positions.

    Images of the h-bar magnetic energy waveparticle of ~175 picoyoctometers are available online at http://www.symmecon.com with the complete RQT atomic modeling manual titled The Crystalon Door, copyright TXu1-266-788. TCD conforms to the unopposed motion of disclosure in U.S. District (NM) Court of 04/02/2001 titled The Solution to the Equation of Schrodinger.

  6. #6 Excited State
    December 22, 2009

    I can vouch for the fact that at least one fine bookstore had at least one copy for sale today. And that copy has been purchased by me.

  7. #7 Johnson
    December 26, 2009

    Very soon, studies of quantum tunneling reactions will be possible using aneutronic fusion reactor.

The site is currently under maintenance and will be back shortly. New comments have been disabled during this time, please check back soon.