It was 20 years ago when Nobel Laureate Leon Lederman coined the term “God Particle” to describe what has since been confirmed as the Higgs Boson, the subject at the center of today’s announcement of the Nobel Prize in Physics. Lederman wrote at the time:
“Why God particle?… the publisher wouldn’t let us call it the Goddamn Particle, though that might be a more appropriate title, given its villainous nature and the expense it is causing.”
Now that the Higgs Boson has been discovered, Lederman is back with a new book that continues where his previous one left off. Beyond the God Particle (Prometheus Books, 2013), written with Dr. Christopher Hill, talks about “the future of particle physics and the mysteries of the universe yet to be unraveled.”
Below is an exclusive excerpt from the book — keep reading for your chance to win a copy!
A Simple Home-Brew Experiment
Get a beach ball and a straw. Have someone blindfold you. Have your assistant take some randomly chosen small items unknown to you, like a peanut, an acorn, a coin, nuts and bolts, a few other small things, and place them on a table in front of you. Now, while still blindfolded, take hold of the beach ball with both hands. Holding only the ball, try to use it gently as a probe of the small objects on the table, the peanut, the acorn, etc. Can you discern which little object is which, while blindfolded, and coming into contact with them only through the very large beach ball? We would guess not, unless you peeked.
Next, take one end of the long straw and, while still blindfolded, use it to trace out the forms of the same small objects. Can you now discern what these objects are and which is which? When you trace out the objects’ shapes you must use a little thought and a little imagination to try to figure out what each of them is — you’ve become both an experimentalist and a theoretical physicist at the same time — like Enrico Fermi. With enough effort and thought you can probably figure out what little objects were placed before you on the table. Perhaps you can tell a dime from a nickel, and chunk of cauliflower from a golf ball. Go ahead — try it!
One thing is clear, if not obvious, from this experiment: a probe that is many times larger than the object to be probed does not work very well. Holding the beach ball, we doubt you can discern a nickel from a dime, if you can even detect either of them. On the other hand, probes that are much smaller than the object itself allow us to readily resolve the object’s structure — even without seeing it with our eyes. This simple principle holds true in all of the strata of the onion of nature, including the stratum of subatomic particles. To explore the structure of the unknown “something,” we must construct a probe that is smaller than the “something” we seek to study.
This seems at first blush to pose what appears to be an insurmountable barrier to studying small objects, like the innards of an atom or a particle inside an atom. How can we study a particle’s inner structure if all we have are other particles of the same size? Ah-ha! Here is where two of the greatest revolutions of science come to our aid: the quantum theory and Einstein’s theory of relativity.
Essentially, we learn from quantum theory that all particles in nature are also waves. This seems to be a ridiculous and nonsensical paradox, but it is the mysterious and jarring reality of quantum theory. The effects of waves vs. particles for most things don’t show up until we reach atomic dimensions, but they can be seen readily for ordinary light. But to be precise, a quantum state is neither a particle nor a wave — it is both at once!
Small objects can be described by quantum mechanical waves that are associated with the probability of detecting a point-like particle at any point in space and time. That is a mouthful, and the interested reader should grab a copy of our book Quantum Physics for Poets (Amherst, NY: Prometheus Books, 2011). However, if you can just “ride the wave” with us for a few more paragraphs, you need only accept that a wave always has a characteristic wavelength. The wavelength is just the familiar distance between two crests or two troughs of a wave, like a water wave. It is the quantum wave-length that tells us how big an object is when it used as a probe.
Now here is a second relevant fact about quantum physics: as we increase the energy of any particle, its quantum wavelength becomes smaller and smaller. When the wave motion approaches the speed of light, then Einstein’s theory of relativity kicks in. If you double the energy of a particle moving near the speed of light, you will halve its quantum wavelength. So, investing a lot of energy in a particle makes its quantum wavelength smaller. This, in principle, allows us to make an arbitrarily tiny probe simply by accelerating a particle to arbitrarily high energies. This is the most important principle underlying microscopes and particle accelerators. The more energy in a particle, the smaller it becomes. And, by the way, you now understand why today’s particle accelerators are very large: it takes a very large accelerator to put a lot of energy into a particle to make it become a smaller probe.
The wavelength of ordinary visible light ranges from, approximately, higher-energy blue light, 0.00004 centimeters (4 × l0-5 cm, about 3 eV per photon; recall that a centimeter is about a half an inch) to lower-energy red light, 0.00007 centimeters (7 × l0-5 cm; about 2 eV per photon). A typical visible particle of a light, a photon, has a quantum wavelength in this range, with an energy of approximately 2 to 3 eV. Objects larger than about 0.0001 centimeters (l0-4 cm) can be readily probed with visible light because they are smaller than the wavelength of the light wave. You need only make a precise optical microscope to do this, and you can see little things that your eye cannot resolve.
However, visible light falters when it is used to study structures smaller than this size scale, such as the tiny components found inside the living cell of a biological organism. Visible light is unable to resolve two objects of much less than 0.00001 centimeters (l0-5 cm) or smaller. You now know the reason: these objects are smaller than the wavelength of the visible photons of light — visible photons are as useless as beach balls to probe such small distance scales. No improvement in your microscope optics can ever improve the image. You could spend hundreds of thousands of dollars on atop-of-the-line Bausch and Lomb microscope, and still the tiniest denizens deep inside living organisms will only appear fuzzy or will not appear at all. Crank up the magnifying power of your microscope, and all you’ll get is a bigger fuzzier image. You absolutely cannot see DNA in an optical (light-based) microscope. Visible light is hopeless to use as a probe of an atom at the atomic-size scale of 0.00000001 centimeter (10-8 cm) or less.
Fortunately, at shorter distance scales, even down to the atomic stratum and beyond, electrons become excellent probes. Electrons can be accelerated in a small type of particle accelerator called an electron microscope, giving them more energy. Electrons, too, have a quantum wavelength, as do all particles. Electrons can easily be endowed with kinetic energies of about 20,000 eV (that’s 10,000 times more than a visible photon). This is the energy of acceleration of the electrons in the old TV picture tubes that could at one time have been found in any household but that have now gone the way of the horse and buggy. At this energy the electrons have a quantum wavelength of about 0.000000001 centimeters (10-9 cm), considerably smaller than that of visible light, and they can be used to make images of DNA, a virus, and even resolve individual atoms.
Beyond the God Particle is available on Amazon today.
If you’d like to win a copy of the book, just leave a comment below with the hashtag #GoddamnParticle and I’ll select a random winner next week!