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Category: cosmology – Page 74

It’s still just a plan, but a new telescope could soon be measuring gravitational waves. Gravitational waves are something like the sound waves of the universe. They are created, for example, when black holes or neutron stars collide.

The future gravitational wave detector, the Einstein Telescope, will use the latest laser technology to better understand these waves and, thus, our universe. One possible location for the construction of this is the border triangle of Germany, Belgium and the Netherlands.

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Black holes and neutron stars are among the densest known objects in the universe. Within and around these extreme astrophysical environments exist plasmas, the fourth fundamental state of matter alongside solids, liquids, and gases. Specifically, the plasmas at these extreme conditions are known as relativistic electron-positron pair plasmas because they comprise a collection of electrons and positrons—all flying around at nearly the speed of light.

While such plasmas are ubiquitous in deep space conditions, producing them in a laboratory setting has proved challenging.

Now, for the first time, an international team of scientists, including researchers from the University of Rochester’s Laboratory for Laser Energetics (LLE), has experimentally generated high-density relativistic electron-positron pair– beams by producing two to three orders of magnitude more pairs than previously reported. The team’s findings appear in Nature Communications.

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What is gravity without mass? Both Newton’s revolutionary laws describing its universal effect and Einstein’s proposal of a dimpled spacetime, we’ve thought of gravity as exclusively within the domain of matter.

Now a wild new study suggesting that gravity can exist without mass, conveniently eliminating the need for one of the most elusive substances in our Universe: dark matter.

Dark matter is a hypothetical, invisible mass thought to make up 85 percent of the Universe’s total bulk. Originally devised to account for galaxies holding together under high speed rotation, it has yet to be directly observed, leading physicists to propose all sorts of out-there ideas to avoid invoking this elusive material as a way to plug the holes in current theories.

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Peering deeply into the cosmos, NASA’s James Webb Space Telescope is giving scientists their first detailed glimpse of supernovae from a time when our universe was just a small fraction of its current age. A team using Webb data has identified 10 times more supernovae in the early universe than were previously known. A few of the newfound exploding stars are the most distant examples of their type, including those used to measure the universe’s expansion rate.

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Most of the universe is invisible to the human eye. The building blocks of stars are only revealed in wavelengths that are outside of the visible spectrum. Astronomers recently used two very different, and very powerful, telescopes to discover twin disks—and twin parallel jets—erupting from young stars in a multiple star system.

This discovery was unexpected, and unprecedented, given the age, size, and chemical makeup of the stars, disks, and jets. Their location in a known, well-studied part of the universe adds to the thrill.

Observations from the U.S. National Science Foundation’s (NSF) National Radio Astronomy Observatory’s (NRAO) Atacama Large Millimeter/submillimeter Array (ALMA) and NASA’s James Webb Space Telescope’s (JWST) Mid-Infrared Instrument (MIRI) were combined for this research.

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University of Copenhagen astrophysicists help explain a mysterious phenomenon, whereby stars suddenly vanish from the night sky. Their study of an unusual binary star system has resulted in convincing evidence that massive stars can completely collapse and become black holes without a supernova explosion.

One day, the star at the center of our own solar system, the Sun, will begin to expand until it engulfs Earth. It will then become increasingly unstable until it eventually contracts into a small and dense object known as a white dwarf.

However, if the Sun were of a weight class roughly eight times greater or more, it would probably go out with a huge bang — as a supernova. Its collapse would culminate into an explosion, ejecting energy and mass into space with enormous force, prior to leaving behind a neutron star or a black hole in its wake.

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In research published earlier this year, physicists from the University of Hyderabad in India say they’re on the path to solving one of the universe’s biggest outstanding problems. Since Edwin Hubble realized the universe is always expanding nearly 100 years ago, scientists have used the “Hubble constant” in calculations on virtually every scale in the universe. But today, estimates for the Hubble constant don’t always align, with a difference of up to 10 percent between calculations made using different methods. (When someone at NASA mixes up meters and yards and loses an entire spacecraft, that’s not even a full 10 percent deviation.)

The paper appears in the peer reviewed journal Classical and Quantum Gravity. The journal has an ongoing, periodically updated “focus issue” specifically about this measurement tension, and the editors explain the problem there—scientists can’t say for sure that the different Hubble constants measured are actually different, rather than just observation or calibration issues.

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