Category: astrophysics

Astronomers Have Uncovered Evidence of “Dynamical Dark Energy”

Baffling Matter in the Universe

For several decades now, since Albert Einstein first posited his general theory of relativity, astronomers have come to understand that what we know and experience to be matter in the Universe is only a tiny fraction of what’s really out there. About 25 percent of the Universe is made up of so-called dark matter, while 68 to 75 percent is dark energy. Both sound like an evil villain’s secret plan for galactic conquest, and indeed they’re often used as such in science fiction.

The reality is, dark matter and dark energy are out there — although their mysterious nature has caused some to credit their existence to an illusion. Though both invisible, we actually see their effects in terms of how these interact with gravity. Dark energy is thought to be a mysterious force that accelerates the expansion of the Universe and is, therefore, considered to be a  cosmological constant according to Einstein — a vacuum energy that’s represented by a constant Equation of State (EoS) of -1, for the purposes of the study.

Now, a collaboration of astronomers, including those from the University of Portsmouth’s (UoP) Institute of Cosmology and Gravitation (ICG), have found evidence that suggests that dark matter may have a dynamic nature. “Since its discovery at the end of last century, dark energy has been a riddle wrapped in an enigma,” ICG director Bob Nichol said in a UoP press release. “We are all desperate to gain some greater insight into its characteristics and origin. Such work helps us make progress in solving this 21st Century mystery.”

A Dynamic Energy

According to their study, published in the journal Nature Astronomy, evidence of dark energy’s dynamic nature comes from high-precision measurements of the Baryonic Acoustic Oscillations (BAO) — periodic fluctuations of a matter composed of protons and neutrons —  at multiple cosmic epochs. These measurements were taken in 2016 by a team that included the lead author of the new study, Gong-Bo Zhao from ICG and the National Astronomical Observatories of China. Combined with a new method which Zhao developed, the astronomers found evidence of dynamical dark energy at an undeniable degree of statistical certainty.

In short, instead of a constant vacuum, dark energy may be some form of dynamical field. “We are excited to see that current observations are able to probe the dynamics of dark energy at this level, and we hope that future observations will confirm what we see today,” Zhao said in the press release.

To confirm their findings, the team is depending on future astronomical surveys to be conducted by next-generation instruments. One of these is the Dark Energy Spectroscopic Instrument (DESI) survey, which is slated to begin work on a 3D cosmic map in 2018. Aside from this, powerful instruments like the long-awaited James Webb Space Telescope could also help to make observations that might shed light on the mysteries of dark energy.

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New Research Suggests Cosmic Rays Hail From Galaxies Beyond the Milky Way

High-Energy Cosmic Rays

For decades, astronomers have known that the Earth is consistently struck by high-energy cosmic rays — charged particles that are usually the nuclei of elements — that originate from a source in space outside our solar system. These cosmic rays possess the highest possible energies observed in nature, even higher than what man-made particle accelerators can reproduce, and now, a team of scientists thinks they might have solved the mystery of their origin.

9 Physics Questions Baffling Scientists [INFOGRAPHIC]
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In a study published Science, the researchers, known collectively as the Pierre Auger Collaboration, suggest that these cosmic signals may originate from outside of the Milky Way. Their conclusions were drawn using recordings from the Pierre Auger Observatory in Argentina, the largest cosmic ray observatory currently in existence, and other data.

Although cosmic rays with energy greater than two joules rarely reach Earth, when they do, their interaction with nuclei in the planet’s atmosphere creates a shower of electrons, photons, and muons, making them detectable by researchers. These showers of more than 10 billion particles spread out across diameters measuring several kilometers.

When one of the particles within this shower hits one of the Pierre Auger Observatory’s 1,600 detectors, which are spread out over an area of 3,000 square kilometers (1,158 square miles), researchers can determine its originating direction. In the new research, the Auger collaboration studied the arrival directions of more than 300,000 cosmic particles and discovered that the arrival rates of the cosmic rays vary and aren’t uniformly spread in all directions. The rate is actually higher for certain directions.

According to the team, this anisotropy indicates an extragalactic origin for the cosmic particles, as many are coming from an area where the distribution of galaxies is fairly high. However, because the direction points toward a broad area of the sky, the specific sources remain undetermined.

Our Celestial Origins

We still have much to learn about cosmic rays, and the Pierre Auger Collaboration expects to supplement their findings when upgrades to the Auger Observatory are completed in 2018. Still, this new discovery is worthwhile. Any new knowledge about these particles can help us better understand matter from outside the solar system and, as this research suggests, from outside the Milky Way.

“We are now considerably closer to solving the mystery of where and how these extraordinary particles are created, a question of great interest to astrophysicists,” University of Wuppertal professor Karl-Heinz Kampert, a spokesperson for the Auger collaboration, said in a press release.

Figuring out the mechanisms behind these cosmic rays could help explain how galaxies form and what in their composition accounts for the creation of such high-energy particles. Furthermore, since these cosmic rays are made of particles that are also found on Earth, they could also provide important clues into the fundamental questions about our origins — perhaps even the origins of the universe itself.

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Water Bears Could One Day Outlive Everything Except the Sun Itself

The Strongest Bear

Tardigrades are virtually microscopic critters that are extremophiles in the most, well, extreme sense. They often go by the name “water bears” (or sometimes “moss piglets”) because, while they are segmented and have eight legs, when magnified, they look like adorable, chubby little gummy bears — scientifically speaking.

So You Want To Kill A Tardigrade? [Comic]
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But the extreme nature of these organisms isn’t in their cuteness, it’s in their virtual indestructibility. That’s right, what you may have heard before is true. Tardigrades can survive just about anything — even the vacuum of space (for a limited period of time, of course).

Water bears prefer to live in moist environments like within the sediment at the bottom of lakes. But these hearty animals can survive unbelievable temperatures, radiation, extreme pressure, and so much more. This is why, according to a recent study published in Nature by researchers from the Oxford and Harvard, tardigrades might be the last species (of anything on Earth) still alive when the Sun dies.

The Last Species

David Sloan was part of the team that explored whether or not tardigrades could survive asteroid impact, gamma ray bursts, and supernovae (the explosion marking the death of a star). “To our surprise we found that although nearby supernovae or large asteroid impacts would be catastrophic for people, tardigrades could be unaffected,” Sloan said in an interview for a Harvard press release. “Therefore it seems that life, once it gets going, is hard to wipe out entirely.”

So, if these researchers are right, why does it matter? Well, this research helps to advance more than just the understanding of tardigrade biology. With the discovery of Trappist-1, recent obstacles found in the search for life on Mars, and the potential to find life on Titan, the study of extremophiles is essential to the quest to find life outside of Earth.

The better that we understand the limits and boundaries of life as we know it to exist on Earth, the better equipped we will be to search for life in the cosmos.

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Noted Scientists Who Passed Away in 2016

Noted_Scientists_Who_Passed_Away_in_2016_Rev4

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Worlds Without End: The Many Kinds of Parallel Universes

Multiversal

It’s a frequent staple of science fiction—the notion that there’s another universe out there, coextensive with yet sejunct from our own; a distinct, alternate reality populated by our doppelgängers, who made all the right choices and are happily living the life we always dreamed for ourselves.

Or perhaps there’s a “multiverse”—a multitude of divergent spacetime continua, offspring of that same primordial Big Bang that gave rise to our own, each exhibiting some uniquely different physical, mathematical, or chemical property that might preclude the evolution of life as we know it.

These are familiar concepts—but what is a parallel universe, really? There are nearly as many definitions as there are potential universes in a multiverse, but let’s take a look at just a few of the myriad possibilities of cosmological plurality.

Many Worlds

Imagine an infinite universe. That’s not exactly in keeping with the best theoretical models propounded by cosmologists, which indicate we exist within an expanding but definitely finite universe that arose some 14 billion years ago.

But if the universe were infinite, then it’s mathematically conceivable that somewhere out there amidst all that immeasurable vastness is a lonely pocket of spacetime where matter and energy have assumed identical, or nearly identical, configurations to our own little corner of cosmic creation.

This form of “parallel universe” would be safely cushioned from us by the universal speed limit set by the velocity of light; but if you really wanted to get there, it’s been calculated that an identical cosmological volume would only be 1010^115 meters away, and your identical copy just 1010^29 meters away.

And that’s hardly the strangest form of parallel universe. Some cosmologists envision the early inflationary epoch spawning a multitude of “bubble universes”—in other words, the universe expanded at such a breakneck speed that pocket spacetimes pinched off and became contiguous but separate universes.

“Every experiment that brings better credence to inflationary theory brings us much closer to hints that the multiverse is real,” says Andrei Linde, a theoretical physicist at Standford University.

And there are, of course, many other scenarios that admit of cosmological parallelism. If certain superstring cosmologies are correct, our universe is a 3-dimensional “brane,” one of many, floating like drifting plankton within a hyperdimensional “bulk.” Or, according to the many-worlds interpretation of quantum mechanics, in which alternate universes are continually generated by every particle in the universe exploring every possible timeline, we’re living in a sea of infinite potential subject to our every whim.

The cyclic, oscillating ekpyrotic model of the universe.
The cyclic, oscillating ekpyrotic model of the universe.

Voyage to Another Universe

So even if there are multiple universes floating around out there somewhere, what are the odds of us ever being able to reach and explore one? Probably less than zero. We’ve already discussed above the physical impossibility of traveling fast enough to reach the disparate pockets of statistical repetition in an infinite universe; the odds hardly improve when it comes to universes even further removed from us.

And if the brane-theories are remotely correct, it would require liberating oneself completely from the tridimensional constraints of our local brane and “casting off” into the hyperdimensional spaces beyond, hoping somehow to locate and enter another brane. Or, if the “ekpyrotic” scenario is correct, you could conceivably wait until two branes collide, and make the transition at that catastrophic and highly uncertain point in time. This all assuming one is in possession of near-godlike powers of control over matter and energy, and is invulnerable to cosmos-creating energies.

Bottom line: parallel universes or no, we’ve got plenty to keep us occupied within the humble ambit of our own restricted and provincial little spacetime configuration, so perhaps it’s time we adjust our expansive imaginations to just accept the Lilliputian dimensions of our local spacetime.

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The Evolution of Human Understanding of the Universe [INFOGRAPHIC]

How Mankind Viewed the Universe from Ancient to Modern Times

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