Seeing the smallest objects requires humongous energy

It is an interesting aspect of the universe and an ironic sense of unity that it requires more energy to see smaller objects. This is the result of the properties of waves in general and specifically the nature of electromagnetic waves.

We see objects with our eyes because light reflects off them. Our brains take this mangled mix of light waves of different frequencies and put it together to create a color image of our surroundings.

The spectrum of visible light consists of a range of wavelengths that seem small — 400 to 700 nanometers and a color range of violet through red. Anything smaller than 400 nm is virtually invisible.

Waves are incapable of “seeing” anything smaller than their wavelength. This is visible even with other types of physical waves, such as ocean waves. When an ocean wave encounters a small object such as a post sticking out of the water, the wave front bends ever so slightly before returning to its undisturbed state.

This is why your microwave oven has a screen with small holes in the glass door. Because the holes are smaller than the microwaves, the screen reflects them as if it were solid metal. Consumer ovens usually use 2.45 gigahertz — a wavelength of about 4.8 inches. The holes in my microwave door’s screen are about 0.075 inches, much smaller than the microwave wavelength.

A visible light microscope is not of much use for objects smaller than 1 micron (0.001 millimeter or 1,000 nm) because they usually use monochromatic light of about 550 nm. To see smaller objects requires the use of X-rays, which have smaller wavelengths than visible light.

Using X-rays to illuminate small objects is not feasible for two important reasons: X-rays are expensive to produce, and they damage biological tissue due to their high energy.

Therein lies the specific nature of electromagnetic waves that limits the power of microscopes. The wavelength of EM waves is inversely proportional to the energy contained in each photon. As the wavelength becomes smaller, the amount of energy becomes larger.

If the switch from EM waves to photon particles confuses you, it is a fact of the quantum world that EM energy is carried by photons — particles of light, which also have wavelike properties.

This wave-particle duality also applies to very small quantum particles such as electrons.

Hence, we use electron microscopes that rely on the wavelike properties of beams of electrons, which because of the mass of the electron have shorter wavelengths at lower energies than EM waves. The wavelength of electrons and other atomic-size particles is inversely proportional to the momentum of the particle.

An electron microscope can resolve objects down to the size of an atom, about 0.1 nm.

To see even smaller objects, such as the innards of an atomic nucleus, requires even higher energies. The nucleus of an atom is approximately 1 million times smaller than the atom; so, it requires a wavelength 1 million times smaller, or 1 million times the energy required to “see” the atom.

To see the smallest particles that physicists have theorized requires tremendous energies such as those produced in the European Organization for Nuclear Research’s Large Hadron Collider, the most complex machine ever built, which was used to find the elusive Higgs boson in 2012.

In order to study the smallest particles that comprise the universe, we must try to see how the universe was built, and that requires looking at the smallest particles that were created by the big bang.

The irony is that the smallest particles and the largest events in the universe are tangled in the ultimate Gordian knot.