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Gravitational waves from the aftereffects of the most powerful merger of two black holes observed to date detected by researchers; "ringing" effect comes from new black hole assuming a spherical shape (More) | General relativity 101 (More, w/video)

Google delays launch of Gemini, a large language model expected to compete with OpenAI's ChatGPT-4, until January; reports say the model has trouble with some non-English prompts (More)

Ancient redwood trees can recover from severe fire damage by tapping long-buried buds, which have laid dormant under their bark for centuries (More)

 

Primordial Fractures in Space Time

The early universe may have been such a violent place that space-time itself fractured like a pane of glass. Those fractures would have released floods of gravitational waves, and a team of astronomers has discovered that we may have already detected these ripples in the fabric of space-time.

The team, who reported their results recently in a paper submitted for publication in the Journal of Computational Astrophysics and published on arXiv.org(opens in new tab), claim that they have seen evidence for so-called domain walls in the early universe.

When our universe was incredibly young, it was also incredibly exotic. The four forces of nature were bound up into a single, unified force. We do not know what that force looked like or how it operated, but we know that as the universe cooled and expanded, that unified force fractured into the four familiar forces we have today. First came gravity, then the strong nuclear force splintered off, and lastly, the electromagnetic and weak nuclear forces split from each other.

With each of these splittings, the universe completely remolded itself. New particles arose to replace ones that could exist only in extreme conditions previously. The fundamental quantum fields of space-time that dictate how particles and forces interact with each other reconfigured themselves. We do not know how smoothly or roughly these phase transitions took place, but it's perfectly possible that with each splitting, the universe settled into multiple identities at once.

This fracturing isn't as exotic as it sounds. It happens with all kinds of phase transitions, like water turning into ice. Different patches of water can form ice molecules with different orientations. No matter what, all the water turns into ice, but different domains can have differing molecular arrangements. Where those domains meet walls, or imperfections, fracturing will appear.  READ MORE...

Breakthrough for Gravitational Waves

Artist’s concept of gravitational waves propagating through space.

New laser breakthrough to help increase understanding of gravitational waves.

Scientists have created a proof-of-concept setup of a new laser eigenmode sensor that offers over 1,000 times the sensitivity. After translating this work to gravitational wave detectors, they will offer the unprecedented precision needed to test the fundamental limits of general relativity and probe the interiors of neutron stars.

Gravitational wave scientists from The University of Western Australia (UWA) have led the development of a new laser mode sensor with unprecedented precision that will be used to probe the interiors of neutron stars and test the fundamental limits of general relativity.

Research Associate from UWA’s Center of Excellence for Gravitational Wave Discovery (OzGrav-UWA) Dr. Aaron Jones, said UWA co-ordinated a global collaboration of gravitational wave, metasurface, and photonics experts to pioneer a new method to measure structures of light called “eigenmodes.”

“Gravitational wave detectors like LIGO, Virgo, and KAGRA store enormous amount of optical power, and several pairs of mirrors are used to increase the amount of laser light stored along the massive arms of the detector,” Dr. Jones said.  READ MORE...

Gravitational Waves

As in history, revolutions are the lifeblood of science. Bubbling undercurrents of disquiet boil over until a new regime emerges to seize power. Then everyone's attention turns to toppling their new ruler. The king is dead, long live the king.

This has happened many times in the history of physics and astronomy. First, we thought Earth was at the center of the solar system — an idea that stood for over 1,000 years. Then Copernicus stuck his neck out to say that the whole system would be a lot simpler if we are just another planet orbiting the sun. Despite much initial opposition, the old geocentric picture eventually buckled under the weight of evidence from the newly invented telescope.

Then Newton came along to explain that gravity is why the planets orbit the sun. He said all objects with mass have a gravitational attraction towards each other. According to his ideas we orbit the sun because it is pulling on us, the moon orbits Earth because we are pulling on it. Newton ruled for two-and-a-half centuries before Albert Einstein turned up in 1915 to usurp him with his General Theory of Relativity. This new picture neatly explained inconsistencies in Mercury's orbit, and was famously confirmed by observations of a solar eclipse off the coast of Africa in 1919.

Instead of a pull, Einstein saw gravity as the result of curved space. He said that all objects in the universe sit in a smooth, four-dimensional fabric called space-time. Massive objects such as the sun warp the space-time around them, and so Earth's orbit is simply the result of our planet following this curvature. To us that looks like a Newtonian gravitational pull. This space-time picture has now been on the throne for over 100 years, and has so far vanquished all pretenders to its crown. The discovery of gravitational waves in 2015 was a decisive victory, but, like its predecessors, it too might be about to fall. That's because it is fundamentally incompatible with the other big beast in the physics zoo: Quantum theory.

The quantum world is notoriously weird. Single particles can be in two places at once, for example. Only by making an observation do we force it to 'choose'. Before an observation we can only assign probabilities to the likely outcomes. In the 1930s, Erwin Schrödinger devised a famous way to expose how perverse this idea is. He imagined a cat in a sealed box accompanied by a vial of poison attached to a hammer. The hammer is hooked up to a device that measures the quantum state of a particle. Whether or not the hammer smashes the vial and kills the cat hinges on that measurement, but quantum physics says that until such a measurement is made, the particle is simultaneously in both states, which means the vial is both broken and unbroken and the cat is alive and dead.  TO READ MORE, CLICK HERE...