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Category: evolution – Page 5

As the universe evolves, scientists expect large cosmic structures to grow at a certain rate: dense regions such as galaxy clusters would grow denser, while the void of space would grow emptier.

But University of Michigan researchers have discovered that the rate at which these large structures grow is slower than predicted by Einstein’s Theory of General Relativity.

They also showed that as dark energy accelerates the universe’s global expansion, the suppression of the cosmic structure growth that the researchers see in their data is even more prominent than what the theory predicts. Their results are published in Physical Review Letters.

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Extraterrestrial and artificial life have long captivated the human mind. Knowing only the building blocks of our own biosphere, can we predict how life may exist on other planets? What factors will rein in the Frankensteinian life forms we hope to build in laboratories here on Earth?

An open-access paper published in Interface Focus and co-authored by several SFI researchers takes these questions out of the realm of science fiction and into scientific laws.

Reviewing case studies from thermodynamics, computation, genetics, cellular development, , , and evolution, the paper concludes that certain fundamental limits prevent some forms of life from ever existing.

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The Hubble Space Telescope has captured imagery of the R Aquarii binary star system from 2014–2023. The images have been time-lapsed here to show the evolution of the region.

Credit: NASA, ESA, M. Stute, M. Karovska, D. de Martin \& M. Zamani (ESA/Hubble) | edited by Space.com.

Music: You Want Dark Tunes? by Ave Air / courtesy of http://www.epidemicsound.com

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Astronomers have discovered a new way to study black holes, the mysterious cosmic entities that destroy anything in their path. By observing X-ray bursts from a star being torn apart by a black hole, researchers calculated the black hole’s spin rate for the first time using X-rays. The black hole was found spinning at nearly 50 percent of the speed of light. This research, published in Science, opens new possibilities for understanding black holes’ behavior and evolution.

The discovery dates back to November 2014, when astronomers observed a supermassive black hole in a galaxy 300 million light years away. This black hole ripped apart a star that had ventured too close, an event known as a tidal disruption flare. The flare generated intense bursts of X-rays that were visible from Earth. Since black holes themselves don’t produce many X-rays, researchers saw an opportunity to study this flare closely.

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The course of evolution on Earth was altered by a series of severe environmental crises caused between 185 and 85 million years ago in the oceans, according to scientists.

The phenomenon, described as a ‘tag-team’ between the oceans and continents, severely harmed the marine life which existed during that phase and also changed the evolution course on our planet.

The oceanic anoxic events, as per the term given by the researchers, occurred when the dissolved oxygen in the water depleted to a critically low level.

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Salt, or more precisely the sodium it contains, is very much a “Goldilocks” nutrient. Low sodium levels cause a drop in blood volume, which can have serious, sometimes deadly, health consequences. Conversely, too much salt can lead to high blood pressure and cardiovascular disease.

In modern America, where most people consume a , almost no one is in danger of having too little salt. However, given the critical importance of sodium for body and brain functions, evolution has developed a powerful drive to consume salt in situations where there is a deficiency.

Understanding the brain circuitry that controls salt appetite has proved elusive, but now a new study by University of Iowa researchers has identified the first and, thus far, only neurons necessary for salt appetite.

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Which brings us to the big question: what about gravity?

This is something where we can’t be certain, as gravitation remains the only known force for which we don’t have a full quantum description. Instead, we have Einstein’s general relativity as our theory of gravity, which relies on a purely classical (i.e., non-quantum) formalism for describing it. According to Einstein, spacetime behaves as a four-dimensional fabric, and it’s the curvature and evolution of that fabric that determines how matter-and-energy move through it. Similarly it’s the presence and distribution of matter-and-energy that determine the curvature and evolution of spacetime itself: the two notions are linked together in an inextricable way.

Now, over on the quantum side, our other fundamental forces and interactions have both a quantum description for particles and a quantum description for the fields themselves. All calculations performed within all quantum field theories are calculated within spacetime, and while most of the calculations we perform are undertaken with the assumption that the underlying background of spacetime is flat and uncurved, we can also insert more complex spacetime backgrounds where necessary. It was such a calculation, for example, that led Stephen Hawking to predict the emission of the radiation that bears his name from black holes: Hawking radiation. Combining quantum field theory (in that case, for electromagnetism) with the background of curved spacetime inevitably leads to such a prediction.

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Almost 300 binary mergers have been detected so far, indicated by their passing gravitational waves. These measurements from the world’s gravitational wave observatories put constraints on the masses and spins of the merging objects such as black holes and neutron stars, and in turn this information is being used to better understand the evolution of massive stars.

Thus far, these models predict a paucity of black hole binary pairs where each black hole has around 10 to 15 times the mass of the sun. This “dip or mass gap” in the mass range where seldom form depends on assumptions made in the models; in particular, the ratio of the two masses in the binary.

Now a new study of the distribution of the masses of existing black holes in binaries finds no evidence for such a dip as gleaned from the that have been detected to date. The work is published in The Astrophysical Journal.

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