Revolution on a quantum scale will allow us to look deeper into the vastness of space
It is as difficult for the human mind to comprehend the world of the very small—the mysterious, uncertain, quantum world of atoms and particles, for which common sense is of no help—as it is for us to grasp the enormous vastness of space.
Earth is but a small speck of matter in a solar system that is just one out of many billions in the Milky Way galaxy, which itself is just one of a similarly large number of galaxies in a universe that stretches across distances measuring billions of light years. Yet these worlds of the very small and very large are deeply connected in a variety of ways that are both surprising and fundamental. We should expect this connection between the small and large to develop further over the coming decades.
In 1905—a year after Alfred Maul's rocket-borne camera took a photo from an altitude of 2,000 ft., and not quite two years after the Wright brothers' first successful flight—the Nobel Prize in physics was awarded to Philipp Lenard. By coincidence, 1905 was also the year that Lenard's measurements of the photoelectric effect were explained by Albert Einstein, who postulated that light waves could also be thought of as particles, discrete packets or quanta of energy now known as photons. This paper won Einstein the Nobel Prize, and the confusing wave-particle duality it implied helped launch the quantum revolution.
It's now 2011. The advances in rocketry and aviation have been stunning. A fundamental understanding of the quantum world has given us the transistor and Moore's Law, the Internet and cell phones. Remarkably, these two independent factors from the worlds of large and small may be multiplied. GPS uses satellites with atomic clocks to tell us where we are anywhere on Earth to incredible precision. The Hubble Space Telescope captures photons from distant galaxies and produces spectacular images using detector arrays that were invented at Bell Labs—another Nobel prize—and further developed at the(JPL) for eventual use on Hubble. And Curiosity, the Mars Science Laboratory rover, will soon use a JPL-developed, quantum-engineered laser to search for signs of life on Mars.
This revolution will continue with the development of sensors able to detect single photons across the spectrum. Very large visible and infrared arrays with millions or billions of pixels are now available for astronomical telescopes as well as planetary instruments and Earth-observing missions. Important parameters such as cost, performance and array size will continue to improve, thanks to the atomic-layer-scale quantum engineering of semiconductor structures.
In the microwave part of the spectrum, similar semiconductor tricks enable electronically controlled transmit/receive arrays that allow both passive and active large-area imaging with high resolution. For ultimate sensitivity, we can harness yet another quantum effect, superconductivity. Superconducting detectors are now being developed for millimeter and submillimeter wavelengths, with formats far larger than the JPL-produced sub-Kelvin bolometer arrays on the European Space Agency's Herschel and Planck observatories launched in 2009.
The same superconducting technology can also be used to produce visible and infrared cameras capable of measuring the energies of individual photons. Combined with ongoing advances in the development of adaptive lightweight telescopes and high-precision optics, these envisioned advances in detection technologies will give us unprecedented views of the Earth and its atmosphere, the planets, stars and galaxies, and even planetary systems around other stars.
After 1905, Einstein turned his focus to the world of the large. Indeed, the theory of general relativity that he developed by 1915 not only helps GPS determine positions correctly, it also allows us to talk sensibly and precisely about the geometry of the entire universe and its history, providing the framework for the Big Bang some 13.7 billion years ago. This picture is supported in exquisite detail by measurements from's Cosmic Background Explorer and Wilkinson Microwave Anisotropy Probe, with even more detail to come soon from Planck.
And in a tiny fraction of a second just after the Big Bang, the worlds of the very small and very large were the same. Scientists believe that small quantum fluctuations were amplified by a process called “inflation” to form large structures that ultimately led to all the galaxies, stars and planets that we see today. Most amazingly, it should be possible to test these ideas using millimeter-wave superconducting detector arrays on space telescopes.