Tag: Cosmology

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Cosmic Space

Sky survey boosts the case for dark energy’s downturn

Long-exposure photo of Mayall Telescope with circular star trails
A long-exposure photo shows the Mayall Telescope beneath the whirling stars. (Credit: KPNO/ NOIRLab / NSF / AURA / B. Tafreshi)

It’s looking more and more as if dark energy, the mysterious factor that scientists say is behind the accelerating expansion of the universe, isn’t as constant as they once thought.

The latest findings from the Dark Energy Spectroscopic Instrument, or DESI, don’t quite yet come up to the level of a confirmed discovery, but they’re leading scientists to rethink their views on the evolution of the universe — and how it might end.

Readings from DESI’s Data Release 2, published on March 19, suggest dark energy’s influence isn’t as strong as it used to be. Scientists had thought that the universe’s endless expansion would eventually lead to a state of cosmic stasis known as the “Big Chill.” But if dark energy fizzles out, billions or trillions of years from now, the universe may fall back on itself and end up in a reverse Big Bang, or “Big Crunch.”

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Cosmic Space

How dark is the cosmos? Probe provides a far-out answer

New Horizons probe with galactic disk in background
Artwork shows NASA’s New Horizons probe in deep space. (Credit: NASA / JHUAPL / SwRI / Serge Brunier / Marc Postman / Dan Durda)

We know that deep space is dark, but just how dark is it? Or, put another way, how bright is it? And how much of that brightness comes from galaxies? Astronomers have gotten a clearer answer to those questions, thanks to observations sent back from billions of miles away.

Nine years after its history-making flyby of Pluto, NASA’s New Horizons spacecraft measured the brightness of the distant universe from a vantage point in deep, dark space.

“If you hold up your hand in deep space, how much light does the universe shine on it?” Marc Postman, an astronomer at the Space Telescope Science Institute in Baltimore, asked today in a news release. “We now have a good idea of just how dark space really is.”

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Universe Today

Quantum data gets sent through a simulated wormhole

Illustration: Wormhole simulation visualized
The wormhole created by researchers exists purely as data. (Illustration credit: Inqnet / A. Mueller / Caltech)

For the first time, scientists have created a quantum computing experiment for studying the dynamics of wormholes — that is, shortcuts through spacetime that could get around relativity’s cosmic speed limits.

Wormholes are traditionally the stuff of science fiction, ranging from Jodie Foster’s wild ride in “Contact” to the time-bending plot twists in “Interstellar.” But the researchers behind the experiment, reported in the Dec. 1 issue of the journal Nature, hope that their work will help physicists study the phenomenon for real.

“We found a quantum system that exhibits key properties of a gravitational wormhole, yet is sufficiently small to implement on today’s quantum hardware,” Caltech physicist Maria Spiropulu said in a news release. Spiropulu, the Nature paper’s senior author, is the principal investigator for a federally funded research program known as Quantum Communication Channels for Fundamental Physics.

Don’t pack your bags for Alpha Centauri just yet: This wormhole simulation is nothing more than a simulation, analogous to a computer-generated black hole or supernova. And physicists still don’t see any conditions under which a traversable wormhole could actually be created. Someone would have to create negative energy first.

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Fiction Science Club

Why believing in the multiverse isn’t madness

Benedict Cumberbatch as Doctor Strange
Doctor Strange is portrayed by Benedict Cumberbatch in "Doctor Strange in the Multiverse of Madness." (Marvel Entertainment)

What is the multiverse? The idea that the universe we inhabit is just one of many parallel universes gets a superhero shout-out in “Doctor Strange in the Multiverse of Madness,” the latest movie based on Marvel comic-book characters.

And in the opinion of Brian Greene, a theoretical physicist at Columbia University, giving some screen time to the multiverse isn’t such a bad thing — even if the plot has some horror-movie twists.

“I think it’s really good if some of these ideas are brought out in a variety of different ways,” Greene says in the latest episode of the Fiction Science podcast, which focuses on the realm where science and technology intersect with fiction and popular culture.

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Fiction Science Club

Could the God Equation be our ultimate salvation?

Wormhole travel
An artist's conception shows a spaceship heading for a wormhole that leads to a distant galaxy. (NASA Illustration)

In retrospect, it seemed almost sacrilegious.

There we were — on Good Friday, the day that ushers in Christianity’s holiest weekend — talking with theoretical physicist Michio Kaku about the possibility that humanity’s salvation will come from a scientific gospel that’s yet to be written.

A gospel that Kaku calls the God Equation.

The way he sees it, our far-flung descendants will be able to take advantage of the God Equation to leave our tired old universe behind.

“One day, stars will blink out. It’ll get super cold. We’ll all freeze to death as it becomes near absolute zero. Well, that’s trillions of years from now. And I think at that point, we’re so advanced, we’ll harness the Planck energy — the energy at which universes can be created — and we’ll create a bubble of our own,” he explained.

“We’ll leave our universe and go to a younger universe where we can mess that universe up as well,” he said.

You could argue that’s the “new heaven and new earth” promised in the Book of Revelation. Is that sacrilegious? You’ll have to decide for yourselves after listening to the latest episode of the Fiction Science podcast, coming to you from the place where science and technology intersect with fiction and popular culture.

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GeekWire

Neutrino trackers solve a cosmic ray puzzle

Blazar and neutrino
In this artistic rendering, a blazar is accelerating protons that produce pions, which produce neutrinos and gamma rays. One neutrino’s path is represented by a blue line passing through Antarctica, while a gamma ray’s path is shown in pink. (IceCube / NASA Illustration)

An array of detectors buried under a half-mile-wide stretch of Antarctic ice has traced the path of a single neutrino back to a supermassive black hole in a faraway galaxy, shedding light on a century-old cosmic ray mystery in the process.

The discovery, revealed today in a flurry of research papers published by the journal Science and The Astrophysical Journal, marks a milestone for the IceCube Neutrino Observatory at the National Science Foundation’s Amundsen-Scott South Pole Station.

It also marks a milestone for an observational frontier known as multi-messenger astrophysics, which takes advantage of multiple observatories looking at the sky in different ways. Thanks to IceCube’s alert, more than a dozen telescopes were able to triangulate on the neutrino’s source.

“No one telescope could have done this by themselves,” said IceCube lead scientist Francis Halzen, a physics professor at the University of Wisconsin at Madison.

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GeekWire

Our view of black holes may change … again

Brian Greene
Columbia physicist Brian Greene delves into Albert Einstein’s theory of relativity in “Light Falls,” a theater piece that made its debut at the World Science Festival. (Greg Kessler Photo / World Science Festival)

After decades’ worth of mystery, it feels as if physicists are finally closing in on the nature of black holes, thanks to Nobel-winning breakthroughs like the first detections of black hole mergers at the Laser Interferometer Gravitational-wave Observatory.

But Columbia University physicist Brian Greene warns that those matter-gobbling monsters may have a few surprises in them yet.

“To watch the history of this subject unfold from a purely theoretical idea to one that now is driving observational tests is enormously exciting,” Greene told GeekWire.

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GeekWire

Number crunchers are on the trail of dark energy

Saul Perlmutter
Berkeley astrophysicist Saul Perlmutter discusses the implications of the universe’s accelerating expansion at the University of Washington. (GeekWire Photo / Alan Boyle)

Big data just might give astronomers a better grip on the answer to one of the biggest questions in physics: Exactly what’s behind the mysterious acceleration in the expansion rate of the universe, also known as dark energy?

And that means the number crunchers at the University of Washington’s DIRAC Institute have their work cut out for them.

The role of data analysis in resolving the mystery came to the fore on May 14 during a talk given at the DIRAC Institute’s first-ever open house on the UW campus. The speaker was none other than Berkeley astrophysicist Saul Perlmutter, who won a share of the Nobel Prize in physics in 2011 for finding the first evidence of dark energy.

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GeekWire

Stephen Hawking’s ‘Final Theory’ gets published

Hertog and Hawking
Belgian physicist Thomas Hertog meets with Stephen Hawking in 2015. (KU Leuven / Facebook)

Weeks after the death of British physicist Stephen Hawking, his final research paper on the nature of our universe and its place in the wider multiverse was published today in the Journal of High-Energy Physics.

Now it’s up to his co-author, Belgian physicist Thomas Hertog, to keep an eye out for observational evidence for or against Hawking’s “Final Theory.”

The pre-print version of the paper — titled “A Smooth Exit From Eternal Inflation?” — has been circulating for months. It addresses the rather mind-blowing idea that our universe is merely one of the many possible manifestations in a multiverse.

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GeekWire

Even after death, Stephen Hawking stirs up a fuss

Stephen Hawking
Physicist Stephen Hawking visited the Large Hadron Collider’s underground tunnel in 2013. (CERN Photo / Laurent Egli)

The ashes of the late British physicist Stephen Hawking will get a fitting resting place in Westminster Abbey, near the graves of Isaac Newton and Charles Darwin.

But you could argue that the true monuments to Hawking’s memory are his books and theoretical papers, delving into the nature of black holes, the big bang and other cosmic mysteries. And as was often the case during his life, the last paper he completed is stirring up a fuss just days after his death.

Hawking’s so-called “Final Theory” is a paper written with Belgian collaborator Thomas Hertog, and titled “A Smooth Exit from Eternal Inflation?” It hasn’t yet been published in a journal, but it’s said to be under review and is available for inspection on the ArXiv pre-print server.

The paper focuses on hypotheses having to do with cosmic inflation and the idea that our own cosmos is just one of many universes in a multiverse.

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