The recent direct detection of gravitational waves by the Laser Interferometer Gravitational-wave Observatory (LIGO) vindicated an effect first postulated by Albert Einstein a century ago, in 1916. As has been proven so many times before, the smart money is always on Einstein, and even when he was wrong, he was right. Modern physicists are still testing theories such as relativity, to see if they break down under extreme circumstances. But science is still far from knowing everything. Often, new methods and discoveries give us the ability to find questions that we didn’t even know to ask in the first place. So with gravitational waves now in the bag, so to speak, here are five other scientific concepts that physicists are hot on the trail of today.
5. Understanding Quantum Entanglement
The random nature of modern quantum physics is so bizarre, Einstein himself refused to believe its predictions, once quipping that, “God does not play dice with the universe.” Physicists have come to accept quantum theory, however, as it has led to several testable predictions, and even applications: a tunneling diode, for example, requires quantum theory to operate. And one of the very strangest results of quantum physics is what has been termed “spooky action at a distance.” Relativity states that information cannot travel faster than the speed of light, and yet two quantum-entangled particles can react in unison simultaneously, even when separated. What’s going on here?
Clearly there’s still a fundamental principle underlying the very nature of the universe that we have yet to understand. Could we possibly use quantum entanglement to one day transmit information faster than the speed of light? In 2012, researchers in the Canary Islands “quantum teleported” information in photons over a distance of 88 miles. While many scientists are obviously thrilled by the prospect of sending communications into deep space at thousands of times the speed of light, there are more practical applications here on Earth, such as innovations in communications and cryptography.
4. Solving the Mystery of Supersymmetry
The Standard Model of modern physics rests on a theory known as supersymmetry. Sometimes simply referred to as “SUSY,” supersymmetry posits that familiar boson subatomic particles (photons, electrons, top quarks, etc) have fermion partners with similar masses, but different spin states. Supersymmetry in various versions is attractive, as it explains several modern conundrums, such as the hierarchy problem of why forces such as gravity are so much weaker than electromagnetism on small scales. Each hypothetical fermion partner is denoted by an “s” before its name, hence the “electron” becomes the “selectron” the “top quark” becomes the “stop quark,” etc. No direct evidence for supersymmetry particles has yet been discovered, although runs using the Large Hadron Collider near Geneva, Switzerland, have placed lower constraints on their respective masses. The LHC discovered the final boson predicted by the Standard Model in 2013, the Higgs-Boson. Solving the mystery of supersymmetry would vindicate the Standard Model of modern physics.
3. Discovering the Source of Dark Matter
It’s an embarrassing situation for modern astrophysics: Where is the missing 95 percent of the mass-energy budget of the universe? Observing the motions of objects such as the famous Bullet Cluster of galaxies reveals that a sizable amount of mass they’re interacting with must be non-luminous. But what is it? Over the past few decades, two leading theories have emerged, namely MACHOs (Massively Compact Halo Objects, such as neutron stars or black holes) and WIMPs (Weakly Interacting Massive Particles, see supersymmetry in No. 4 above). The WIMP theory has gained footing among a majority of physicists in recent years. Trillions of weakly interacting particles known as neutrinos are passing through you each second, and it’s strange to think that a whole mirror universe made up of a menagerie of weakly interacting particles may exist next to our own. Then there’s the related mystery of dark energy, a force that seems to actually accelerate cosmic expansion. Proposed missions, such as NASA’s Wide-Field Infrared Survey Telescope set to launch in the 2020s, may shed light (bad pun intended) on the nature of dark energy and dark matter.
2. The Possible Existence of Multiple Dimensions
Is the universe fine-tuned for life, or do we merely exist in one of many possible universes? Multiple — or parallel — universes would certainly help clarify puzzling issues that have long puzzled quantum physicists. Some scientists believe this so-called “multiverse” is far more likely to exist than just the single universe we currently know and inhabit. Factors such as the Planck constant, for example, seem precisely tuned for the physics we see today: change the physical parameters of the universe a bit, and atoms would not bond, elements such as carbon would not arise, and life would be impossible. This concept is known as the “anthropic principle,” an idea that states the universe is arranged for life. Of course, that’s life as we know it … and looking out into the universe, we still see mostly inhospitable, radiation-riddled vacuum.
Even stranger ideas exist. Is the universe a hologram? Does it exist inside a black hole? Of course, this just punts the question upstairs a bit, asking where those particular hierarchies came from. In order to be considered science, the idea of multiple dimensions has to put forth a testable prediction. String theory may do just that, though again, it also needs to withstand strict scientific analysis.
1. Developing Sustainable Nuclear Fusion
This has been the dream of the atomic era, and promises a near-limitless supply of energy for our growing power-hungry civilization. But just how close are we to controlled nuclear fusion for commercial purposes? Traditional nuclear power plants rely on fission, or the decay of radioactive elements such as uranium to produce heat. Fusion would harness the energy of the atom itself, which is released when two nuclei fuse together. The Sun has shone for billions of years using the proton-proton chain to fuse hydrogen into helium in its core. The problem is, the core of the Sun is under extremely high pressure and heated to millions of degrees, an environment that is tough to sustain here on Earth. Recently, China claimed some initial success toward sustainable fusion, using a magnetic field to confine a high-energy plasma. Other concepts include using lasers to smash deuterium pellets together. Another exciting possibility is to skip a step, and instead fuse Helium-3 nuclei together for energy. Scarce on the Earth, there’s some evidence that Helium-3 deposited by the solar wind may lay in abundance on the surface of Earth’s Moon. This much-anticipated discovery would obviously transform our planet in ways we can’t begin to imagine.