Starting with the direct detection of gravitational waves in 2015, scientists have relied on a bit of a kludge: they can only detect those waves that match theoretical predictions, which is rather the opposite way that science is usually done.
In a paper in Physical Review Letters scientists from the department Living Matter Physics at the Max Planck Institute for Dynamics and Self-Organization (MPI-DS) propose a mechanism on how energy barriers in complex systems can be overcome. These findings can help to engineer molecular machines and to understand the self-organization of active matter.
When seawater gets cold, it gets viscous. This fact could explain how single-celled ocean creatures became multicellular when the planet was frozen during “Snowball Earth,” according to experiments.
If you make a material thinner and thinner, at a certain point it undergoes a seemingly miraculous transformation: A two-dimensional material that consists of only one or two layers of molecules sometimes has completely different properties than the same material when it is thicker.
In previous research, measurements found that for fast rotations, for example in nuclei like neon-20 or chromium-48, the energy for spinning changes unexpectedly. Scientists attributed this to an anomalous increase in the moment of inertia for fast rotations, likely due to the nuclear matter bulging out. Earlier models suggested that fast-rotating nuclei ultimately become spheres, but newer models have found deformed shapes. Now, large-scale simulations of atomic nuclei have revealed surprising new explanations of the elusive physics of fast-spinning nuclei.
For the first time in nearly 50 years, scientists accurately calculated the moment of inertia and studied its hypothesized anomalous increase through state-of-the-art simulations of nuclei. The simulations for neon-20 replicate the energy measurements. Remarkably, however, the simulations do not find the anomalous increase. Instead, they reveal a change in the interior of the nucleus.
Similar microscopic simulations for chromium-48 confirm this surprising result. Furthermore, the results resolve the long-lasting question of whether a prolate nucleus that starts to quickly spin becomes spherical or oblate. This research, published in Physical Review C, shows that several competing shapes emerge, some prolate and some oblate, which on average appear spherical.
“Significant effort has been invested over the years to pinpoint the physical cause of the radiation drive-deficit problem,” Chen said. “We are excited about this discovery as it helps resolve a decade-long puzzle in ICF research. Our findings point the way to an improvement in the predictive capabilities of simulations, which is crucial for the success of future fusion experiments.”
In NIF experiments, scientists use a device called a hohlraum—approximately the size of a pencil eraser—to convert laser energy into X-rays, which then compress a fuel capsule to achieve fusion.
For years, there has been a problem where the predicted X-ray energy (drive) was higher than what was measured in experiments. This results in the time of peak neutron production, or “bangtime,” occurring roughly 400 picoseconds too early in simulations. This discrepancy is known as the “drive-deficit” because modelers had to artificially reduce the laser drive in the simulations to match observed bangtime.
Nick bostroms simulation argument.
Have you ever paused, looked around, and wondered if everything you see, feel, and experience is real? Or could it be that we’re living in a sophisticated simulation, indistinguishable from reality?
This thought isn’t just a plot from a sci-fi movie; it’s a serious philosophical argument proposed by Nick Bostrom, known as the Simulation Argument. If you’ve ever questioned the nature of reality or pondered over the mysteries of existence, this exploration is for you.
Continue reading “Reality or Simulation? Simulation Argument by Nick Bostrom” »
What would it take to set Uranus ablaze? Is it even possible to burn it in the typical sense? If anyone can figure it out, it’s the Dead Planets Society.
Join Dead Planeteers Leah and Chelsea as they invite planetary scientist Paul Byrne back to the podcast, to join in more of their chaotic antics.
Continue reading “Can We Burn Uranus? | Dead Planets Society Podcast” »
ICYMI, Nobel Laureate Kip Thorne (BS ’62) reached across history, physics, and astronomy to highlight characters and discoveries that changed humanity’s understanding of space and time.
His talk was the 100th in Caltech Astro’s Stargazing Lecture Series.
