This visualization uses data from simulations of orbital motions of gas swirling around at about 30% of the speed of light on a circular orbit around the black hole. Credit: ESO/Gravity Consortium/L. Calçada
It’s relatively easy for galaxies to make stars. Start out with a bunch of random blobs of gas and dust. Typically those blobs will be pretty warm. To turn them into stars, you have to cool them off. By dumping all their heat in the form of radiation, they can compress. Dump more heat, compress more. Repeat for a million years or so.
Eventually pieces of the gas cloud shrink and shrink, compressing themselves into a tight little knots. If the densities inside those knots get high enough, they trigger nuclear fusion and voila: stars are born.
This scanning electron micrograph shows the crater left by the impact of a 10-micrometer particle traveling at more than 1 kilometer per second. Impacts at that speed produce some melting and erosion of the surface, as revealed by this research. Credit: MIT/Hassani-Gangaraj et al.
If there’s one thing that decades of operating in Low Earth Orbit (LEO) has taught us, it is that space is full of hazards. In addition to solar flares and cosmic radiation, one of the greatest dangers comes from space debris. While the largest bits of junk (which measure more than 10 cm in diameter) are certainly a threat, the real concern is the more than 166 million objects that range in size from 1 mm to 1 cm in diameter.
While tiny, these bits of junk can reach speeds of up to 56,000 km/h (34,800 mph) and are impossible to track using current methods. Because of their speed, what happens at the moment of impact has never been clearly understood. However, a research team from MIT recently conducted the first detailed high-speed imaging and analysis of the microparticle impact process, which will come in handy when developing space debris mitigation strategies. Continue reading “Micrometeorite Damage Under the Microscope”
Timeline of the Big Bang and the expansion of the Universe. If the new atomic clock had been turned on at the Big Bang, it would be off by less than a single second now, almost 14 billion years later. Credit: NASA
Physicists have developed an atomic clock so accurate that it would be off by less than a single second in 14 billion years. That kind of accuracy and precision makes it more than just a timepiece. It’s a powerful scientific instrument that could measure gravitational waves, take the measure of the Earth’s gravitational shape, and maybe even detect dark matter.
An artist's illustration of the first stars to appear in the universe.
Credit: N.R. Fuller, National Science Foundation
We need to talk about the dark ages. No, not those dark ages after the fall of the western Roman Empire. The cosmological dark ages. The time in our universe, billions of years ago, before the formation of the first stars. And we need to talk about the cosmic dawn: the birth of those first stars, a tumultuous epoch that completely reshaped the face the cosmos into its modern form.
Those first stars may have been completely unlike anything we see in the present universe. And we may, if we’re lucky, be on the cusp of seeing them for the first time.
Researchers at the Experimental Advanced Superconducting Tokamak facility in China have achieved a new milestone in fusion power. Credit: ipp.cas.cn
Fusion power has been the fevered dream of scientists, environmentalists and futurists for almost a century. For the past few decades, scientists have been attempting to find a way to create sustainable fusion reactions that would provide human beings with clean, abundant energy, which would finally break our dependence on fossil fuels and other unclean methods.
In recent years, many positive strides have been made that are bringing the “fusion era” closer to reality. Most recently, scientists working with the Experimental Advanced Superconducting Tokamak (EAST) – aka. the “Chinese artificial sun” – set a new record by super-heating clouds of hydrogen plasma to over 100 million degrees – a temperature which is six times hotter than the Sun itself!
NASA's Solar Dynamics Observatory has captured images of a growing dark region on the surface of the Sun. Called a coronal hole, it produces high-speed solar winds that can disrupt satellite communications. Image: Solar Dynamics Observatory / NASA
How in the world could you possibly look inside a star? You could break out the scalpels and other tools of the surgical trade, but good luck getting within a few million kilometers of the surface before your skin melts off. The stars of our universe hide their secrets very well, but astronomers can outmatch their cleverness and have found ways to peer into their hearts using, of all things, sound waves. Continue reading “Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves”
The Very Large Telescope in Chile firing a laser from its adaptive optics system. Credit: ESO
Telescopes have come a long way in the past few centuries. From the comparatively modest devices built by astronomers like Galileo Galilei and Johannes Kepler, telescopes have evolved to become massive instruments that require an entire facility to house them and a full crew and network of computers to run them. And in the coming years, much larger observatories will be constructed that can do even more.
Unfortunately, this trend towards larger and larger instruments has many drawbacks. For starters, increasingly large observatories require either increasingly large mirrors or many telescopes working together – both of which are expensive prospects. Luckily, a team from MIT has proposed combining interferometry with quantum-teleportation, which could significantly increase the resolution of arrays without relying on larger mirrors.
Artist's impression of the Nebraska experiment, where the white orbs represent two laser pulses with plasma waves in their wakes. The waves interfere with one another after the laser pulses cross, and electrons ride the wake field waves to higher energy. Credit: University of Nebraska-Lincoln/ELL
A team of researchers from the University of Nebraska–Lincoln recently conducted an experiment where they were able to accelerate plasma electrons to close to the speed of light. This “optical rocket”, which pushed electrons at a force a trillion-trillion times greater than that generated by a conventional rocket, could have serious implications for everything from space travel to computing and nanotechnology.
This series of graphs show the changing density of a cloud of atoms as it is cooled to lower and lower temperatures (going from left to right) approaching absolute zero. Credit: NASA/JPL-Caltech
Despite decades of ongoing research, scientists are trying to understand how the four fundamental forces of the Universe fit together. Whereas quantum mechanics can explain how three of these forces things work together on the smallest of scales (electromagnetism, weak and strong nuclear forces), General Relativity explains how things behaves on the largest of scales (i.e. gravity). In this respect, gravity remains the holdout.
To understand how gravity interacts with matter on the tiniest of scales, scientists have developed some truly cutting-edge experiments. One of these is NASA’s Cold Atom Laboratory (CAL), located aboard the ISS, which recently achieved a milestone by creating clouds of atoms known as Bose-Einstein condensates (BECs). This was the first time that BECs have been created in orbit, and offers new opportunities to probe the laws of physics.
Originally predicted by Satyendra Nath Bose and Albert Einstein 71 years ago, BECs are essentially ultracold atoms that reach temperatures just above absolute zero, the point at which atoms should stop moving entirely (in theory). These particles are long-lived and precisely controlled, which makes them the ideal platform for studying quantum phenomena.
The Cold Atom Laboratory (CAL), which consists of two standardized containers that will be installed on the International Space Station. Credit: NASA/JPL-Caltech/Tyler Winn
This is the purpose of the CAL facility, which is to study ultracold quantum gases in a microgravity environment. The laboratory was installed in the US Science Lab aboard the ISS in late May and is the first of its kind in space. It is designed to advance scientists’ ability to make precision measurements of gravity and study how it interacts with matter at the smallest of scales.
As Robert Thompson, the CAL project scientist and a physicist at NASA’s Jet Propulsion Laboratory, explained in a recent press release:
“Having a BEC experiment operating on the space station is a dream come true. It’s been a long, hard road to get here, but completely worth the struggle, because there’s so much we’re going to be able to do with this facility.”
About two weeks ago, CAL scientists confirmed that the facility had produced BECs from atoms of rubidium – a soft, silvery-white metallic element in the alkali group. According to their report, they had reached temperatures as low as 100 nanoKelvin, one-ten million of one Kelvin above absolute zero (-273 °C; -459 °F). This is roughly 3 K (-270 °C; -454 °F) colder than the average temperature of space.
Because of their unique behavior, BECs are characterized as a fifth state of matter, distinct from gases, liquids, solids and plasma. In BECs, atoms act more like waves than particles on the macroscopic scale, whereas this behavior is usually only observable on the microscopic scale. In addition, the atoms all assume their lowest energy state and take on the same wave identity, making them indistinguishable from one another.
The”physics package” inside the Cold Atom Lab, where ultracold clouds of atoms called Bose-Einstein condensates are produced. Credit: NASA/JPL-Caltech/Tyler Winn
In short, the atom clouds begin to behave like a single “super atom” rather than individual atoms, which makes them easier to study. The first BECs were produced in a lab in 1995 by a science team consisting of Eric Cornell, Carl Wieman and Wolfgang Ketterle, who shared the 2001 Nobel Prize in Physics for their accomplishment. Since that time, hundreds of BEC experiments have been conducted on Earth and some have even been sent into space aboard sounding rockets.
But the CAL facility is unique in that it is the first of its kind on the ISS, where scientists can conduct daily studies over long periods. The facility consists of two standardized containers, which consist of the larger “quad locker” and the smaller “single locker”. The quad locker contains CAL’s physics package, the compartment where CAL will produce clouds of ultra-cold atoms.
This is done by using magnetic fields or focused lasers to create frictionless containers known as “atom traps”. As the atom cloud decompresses inside the atom trap, its temperature naturally drops, getting colder the longer it remains in the trap. On Earth, when these traps are turned off, gravity causes the atoms to begin moving again, which means they can only be studied for fractions of a second.
Aboard the ISS, which is a microgravity environment, BECs can decompress to colder temperatures than with any instrument on Earth and scientists are able to observe individual BECs for five to ten seconds at a time and repeat these measurements for up to six hours per day. And since the facility is controlled remotely from the Earth Orbiting Missions Operation Center at JPL, day-to-day operations require no intervention from astronauts aboard the station.
JPL scientists and members of the Cold Atom Lab’s atomic physics team (left to right) David Aveline, Ethan Elliott and Jason Williams. Credit: NASA/JPL-Caltech
Robert Shotwell, the chief engineer of JPL’s astronomy and physics directorate, has overseen the project since February 2017. As he indicated in a recent NASA press release:
“CAL is an extremely complicated instrument. Typically, BEC experiments involve enough equipment to fill a room and require near-constant monitoring by scientists, whereas CAL is about the size of a small refrigerator and can be operated remotely from Earth. It was a struggle and required significant effort to overcome all the hurdles necessary to produce the sophisticated facility that’s operating on the space station today.”
Looking ahead, the CAL scientists want to go even further and achieve temperatures that are lower than anything achieved on Earth. In addition to rubidium, the CAL team is also working towards making BECSs using two different isotopes of potassium atoms. At the moment, CAL is still in a commissioning phase, which consists of the operations team conducting a long series of tests see how the CAL facility will operate in microgravity.
However, once it is up and running, five science groups – including groups led by Cornell and Ketterle – will conduct experiments at the facility during its first year. The science phase is expected to begin in early September and will last three years. As Kamal Oudrhiri, JPL’s mission manager for CAL, put it:
“There is a globe-spanning team of scientists ready and excited to use this facility. The diverse range of experiments they plan to perform means there are many techniques for manipulating and cooling the atoms that we need to adapt for microgravity, before we turn the instrument over to the principal investigators to begin science operations.”
Given time, the Cold Atom Lab (CAL) may help scientists to understand how gravity works on the tiniest of scales. Combined with high-energy experiments conducted by CERN and other particle physics laboratories around the world, this could eventually lead to a Theory of Everything (ToE) and a complete understanding of how the Universe works.
And be sure to check out this cool video (no pun!) of the CAL facility as well, courtesy of NASA:
