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In the fascinating realm of physics, what seems unachievable is often made possible. Yet in recent years, many researchers have surpassed even this and accomplished groundbreaking feats.
10. Defying the Laws of Cold
Previously, scientists were unable to cool objects past a limit known as the 'quantum barrier.' To freeze an object, a laser is used to slow the atoms and their heat-generating vibrations. Interestingly, laser light also adds heat, preventing temperatures from falling below the quantum limit. Remarkably, physicists engineered a vibrating aluminum drum and succeeded in cooling it to 360 microKelvin, making it 10,000 times colder than the void of space. The drum, just 20 micrometers in diameter (about half the width of a human hair), defied this established boundary.
Previously deemed impossible, this breakthrough was achieved through an innovative laser technique that 'squeezes' light, directing the particles with greater stability in one direction. This eliminated the fluctuations in the laser that otherwise produced heat. The drum is the coldest mechanical object ever recorded, though not the coldest form of matter, which is a Bose-Einstein condensate. Nonetheless, this achievement could eventually play a role in superfast electronics and help unravel the strange behaviors of the quantum world that emerge as materials approach their physical limits.
9. The Most Intense Light
The brilliance of our Sun is already impressive. Now, imagine the combined brilliance of a billion Suns. This is roughly what physicists have managed to replicate in a laboratory. Officially, it is the most intense luminosity ever recorded on Earth, and this light exhibited surprising behaviors. It altered the way objects appeared.
To grasp this, we need to understand how vision works. Photons must scatter off electrons for us to see. Under normal conditions, electrons scatter one photon at a time. When something brightens, its shape typically stays the same as it would in dimmer light. However, the powerful laser used in this experiment scattered an incredible 1,000 photons. Since scattering enables visibility, the rate at which it occurred affected how the photons behaved and, as a result, how an illuminated object was perceived. This unusual effect became more pronounced as the super-bright light increased in strength. As the photons’ energy and direction were altered, the light and colors were produced in unexpected ways.
8. Molecular Black Hole
A group of physicists recently created a phenomenon that acted like a black hole. They used the most powerful X-ray laser in the world, the Linac Coherent Light Source (LCLS), to target iodomethane and iodobenzene molecules. The team expected the X-ray beam to strip most of the electrons from the iodine atom, creating a vacuum. In previous experiments with weaker lasers, this vacuum would draw electrons from the outer parts of the atom. When LCLS was used, the expected result occurred—but with a twist. Instead of halting with the iodine atom, it began pulling electrons from the surrounding hydrogen and carbon atoms. It was as if a tiny black hole had formed within the molecule.
Further bursts of the X-ray laser knocked out the stolen electrons, but the void continued to draw more in. This cycle repeated itself until the entire molecule erupted. The iodine atom, being the largest, absorbed an enormous amount of X-ray energy, losing its original electrons. The resulting positive charge was powerful enough to strip electrons from the smaller atoms around it.
7. Metallic Hydrogen
It has long been dubbed the 'holy grail of high-pressure physics,' but until recently, no scientist had managed to create metallic hydrogen. This elusive form of hydrogen, which could potentially be a superconductor, has been highly sought after. The idea of transforming hydrogen into a metal was first proposed in 1935, with physicists hypothesizing that extreme pressure could trigger this transformation. The challenge was generating the necessary pressure to achieve this.
In 2017, a team of US researchers adapted an existing technique and successfully brought metallic hydrogen into existence for the first time. Earlier experiments were carried out in a device known as a diamond anvil cell, which uses two synthetic diamonds placed opposite each other to create pressure. However, these diamonds would often crack at the crucial point. The team modified the cell's chamber and introduced a new shaping and polishing method that prevented the fractures. This innovation allowed the device to generate an astounding pressure of over 71.7 million pounds per square inch—higher than the pressure found at the center of the Earth.
6. Computer Chip With Brain Cells
In the world of electronics, light could eventually replace electricity as the driving force. Decades ago, physicists recognized the potential of light in this context, particularly because its waves can travel in close proximity, enabling multiple tasks to be performed simultaneously. Traditional electronics rely on transistors to manage the flow of electricity, which imposes limits on performance. A groundbreaking invention has emerged in the form of a computer chip designed to mimic the human brain. This chip 'thinks' rapidly by using light beams that interact with one another, much like the way neurons function.
In earlier times, neural networks were relatively basic, but the machinery stretched across multiple tables. Smaller versions were considered impossible. Now, a new chip made from silicone is just a few millimeters wide and processes with 16 neurons. Laser light enters the chip and divides into beams, each representing numbers or data through variations in brightness. The intensity of the light exiting the chip provides the solution to the computation or whatever task it was assigned.
5. An Impossible Type of Matter
Meet supersolids. This intriguing material isn’t as solid as its name suggests. It combines the rigid crystalline structure of solids with the fluid properties of liquids. This paradox was believed to be unattainable, as it contradicts known physics. However, in 2016, two independent research teams succeeded in creating matter that exhibited the characteristics of a supersolid. Remarkably, both teams used distinct techniques to achieve what was thought to be impossible with a single approach.
The Swiss researchers produced a Bose-Einstein condensate, the coldest known form of matter, by cooling rubidium gas to extremely low temperatures in a vacuum. They then transferred the condensate into a dual-chamber device with opposing small mirrors. Lasers caused the transformation, and the particles arranged into a solid-like crystalline structure while still behaving like a fluid. The American researchers achieved a similar hybrid matter, though they used evaporative cooling and lasers on sodium atoms. Using lasers, they adjusted the atoms' density until they formed the crystal-like structure in their liquid sample.
4. Negative-Mass Fluid
In 2017, physicists achieved something truly astonishing: they created a form of matter that moves toward the force that was pushing it away. While it’s not exactly a boomerang, it possesses what is known as negative mass. We are all familiar with positive mass, where pushing an object causes it to accelerate in the direction of the force applied. However, for the first time, a fluid was created that behaves in a completely unfamiliar way—it moves backward when pushed.
The fluid was once again a Bose-Einstein condensate, created by cooling rubidium atoms to their lowest temperature. The result was a superfluid with typical mass. Scientists used lasers to compress the atoms, and a second set of lasers disturbed their spin. Under normal circumstances, when released, the fluid would have spread outward from its center, in the direction of the force. However, the altered rubidium superfluid didn’t spread out but instead halted, demonstrating the bizarre behavior of negative mass.
3. 2-D Magnet
For decades, physicists have tried and failed to create a true 2-D magnet. A genuine 2-D magnet is one that retains its magnetic properties even when reduced to just a single layer, only one atom thick. For years, it seemed like such a magnet might not even be possible.
In June 2017, researchers turned to chromium triiodide in their efforts to finally create a true 2-D magnet. This compound proved promising for several reasons: it was a layered crystal ideal for thinning, it possessed a permanent magnetic field, and its electrons had a favored spin direction. These key characteristics enabled chromium triiodide to maintain its magnetism, even when reduced to a single layer of atoms.
The first actual 2-D magnet was created at an unexpectedly warm –228 degrees Celsius (–378 °F). It lost its magnetic properties when a second layer was removed but regained them when additional layers were reintroduced. At present, it doesn’t function at room temperature and is sensitive to oxygen, but these 2-D magnets could enable experiments that were previously unimaginable.
2. Bragg Mirrors
A Bragg mirror is an incredibly tiny structure, measuring just 1,000 to 2,000 atoms, and reflects minimal light. However, it is still capable of reflecting light, making it essential in applications where minuscule mirrors are required, such as in advanced electronics. The atoms form an unusual structure, suspended in a vacuum, and aligned in a bead-like pattern. In 2011, a German team created the most reflective Bragg mirror to date (80 percent reflectivity) by using a laser to arrange ten million atoms into a lattice formation.
Since then, Danish and French research teams have drastically reduced the number of atoms needed. Rather than focusing on clustered atoms, they arranged them next to microscopic optical fibers. When spaced properly, the Bragg condition was satisfied, reflecting light directly back to its source. As light passed through, some of it escaped the fiber and interacted with the atoms. The Danish and French configurations reflected about 10 and 75 percent of the light, respectively, while both methods returned the light in the reverse direction down the fiber. This breakthrough not only holds potential for transformative technological advances, but it could also be valuable for future quantum devices, as the atoms used the light field to influence one another.
1. Time Crystals
When Frank Wilczek, a Nobel Prize-winning physicist, introduced the concept of time crystals, it seemed like an outlandish idea—especially the part where they could create movement at ground state, the lowest possible energy state of matter. Normally, movement requires energy, and at ground state, energy is nearly nonexistent. Wilczek theorized that perpetual motion could be achieved by continuously flipping the alignment of a crystal's atoms in and out of ground state. Such a structure would repeat over time, generating continuous motion without the need for energy. Although this concept violated known physics, by 2017, five years after Wilczek's proposal, scientists discovered how to create time crystals.
A team of researchers manipulated ten interconnected ytterbium ions using two lasers. One laser generated a magnetic field, while the other altered the spin of the atoms, causing them to flip as Wilczek had envisioned. At Harvard, another breakthrough occurred when nitrogen impurities in diamonds were flipped to create a time crystal. Even though time crystals are now recognized and no longer dismissed as an insane theory, they still need to be periodically stimulated to keep flipping. While not the perpetual motion machines Wilczek imagined, time crystals are still a unique and fascinating phenomenon unlike anything else in research.
