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The universe is dying, new study confirms

Star production peaked three billion years after the Big Bang.

This map of the entire sky shows the location of 739 blazars used in the Fermi Gamma-ray Space Telescope's measurement. Brighter areas have stronger gamma rays. Image source: NASA/DOE/Fermi LAT Collaboration
  • Scientists track gamma rays across the universe's extragalactic background to calculate all of the starlight ever produced.
  • For 10.8 billion years, star production has been decelerating.
  • The research team measured nine years worth of data from the universe's 739 known blazars.

The good news is that scientists believe they've figured out how much starlight the universe has ever produced since the Big Bang. Exciting. The bad news? Well, apparently star production peaked a long, long time ago, and ever since, the universe has been in the process of dying. Only seven new stars are born a year these days. You can keep buying green bananas, though; there's time: We still have many billions of years before the stars that already exist go dark and cold.

Counting starlight

In Science, the Fermi-LAT Collaboration published, on November 30, a new inventory and history of the universe's light. So, how much light has the universe produced? 4 × 10⁸⁴ photons. To spell that out, that's 4,000,000,000,000,000,000,000,000,000,000,000,000
000,000,000,000,000,000,000,000,000,000,000,000,000,
000,000,000 photons.

The lead study author of the study, astrophysicist Marco Ajello, said his team was able to measure the entire amount of starlight ever emitted using the Fermi telescope.

"This has never been done before," he told Clemson University's the Newsstand. "Most of this light is emitted by stars that live in galaxies. Every single star that has existed has contributed to this emission, and we can use it to learn all the details about star formation and evolution and galaxy evolution."

The Fermi team has been measuring nine years worth of data from the universe's 739 known blazars.

This map of the entire sky shows the location of 739 blazars used in the Fermi Gamma-ray Space Telescope's measurement. Brighter areas have stronger gamma rays.

Image: NASA/DOE/Fermi LAT Collaboration

What the blazar is a blazar?

As galaxies spin around a supermassive black hole at their center, charged particles circling the event horizon develop strong magnetic fields that further excite the particles, causing them to emit radiation at very high energies. Such galaxies produce a great deal of light at their centers, and they're referred to as "active galactic nuclei" (AGN). Some AGNs seem brighter than others from here on Earth. They're not really — they're just the ones pointed straight at us.

Jets of material shot out of such AGNs are called "blazars." The quasar sound-alike name gets its "Bl" from "BL Lacertae," after the constellation in which the first recorded one, back in 1929, originated. Blazars travel at near light speed, and within them are gamma-ray photons the Fermi Gamma-ray Space Telescope is designed to detect.

Artistic rendering of a blazar accelerating protons that produce pions, which produce neutrinos and gamma rays. Image source: IceCube/NASA

Encounters with the EBL

As they travel across space, blazar gamma-ray photons collide with the universe's extragalactic background (EBL), the background radiation produced by star formation. Says Ajello, "Gamma-ray photons traveling through a fog of starlight have a large probability of being absorbed. By measuring how many photons have been absorbed, we were able to measure how thick the fog was, and also measure, as a function of time, how much light there was in the entire range of wavelengths." He adds, "It's like following the rainbow till the end and finding the treasure. That's what we found."

In terms of the blazars, NASA columnist Ethan Seigel writes, "The closest one comes to us from just 200 million years ago; the most distant has its light arriving after a journey of 11.6 billion years: from when the Universe was just 2.2 billion years old."

Artist's conception of a blazar. Image source: JPL

The timeline behind and ahead

The study's Vaidehi Paliya says, "By using blazars at different distances from us, we measured the total starlight at different time periods. We measured the total starlight of each epoch — 1 billion years ago, 2 billion years ago, 6 billion years ago, etc — all the way back to when stars were first formed."

The notion that the universe is "dying" is due to the fact that star production, which is decreasing, is a grand recycler of energy, matter, and elements that "nourish" the universe. Our survival relies, quite literally, on starlight and its generation. As Dieter Hartmann, another author of the study, says: "Without the evolution of stars, we wouldn't have the fundamental elements necessary for the existence of life."

Hulu's original movie "Palm Springs" is the comedy we needed this summer

Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.

Gear
  • Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
  • As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
  • The film is perfectly timed for a world sheltering at home during a pandemic.
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Two MIT students just solved Richard Feynman’s famed physics puzzle

Richard Feynman once asked a silly question. Two MIT students just answered it.

Surprising Science

Here's a fun experiment to try. Go to your pantry and see if you have a box of spaghetti. If you do, take out a noodle. Grab both ends of it and bend it until it breaks in half. How many pieces did it break into? If you got two large pieces and at least one small piece you're not alone.

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Our ‘little brain’ turns out to be pretty big

The multifaceted cerebellum is large — it's just tightly folded.

Image source: Sereno, et al
Mind & Brain
  • A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
  • The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
  • This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.

Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).

A neural crêpe

A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.

So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.

The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."

Study's cross-sections of a folded cerebellum

Image source: Sereno, et al.

A complicated map

Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."

That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.

It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."

This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."

Bigger and bigger

The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.

"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."

As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."

Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."

Economists show how welfare programs can turn a "profit"

What happens if we consider welfare programs as investments?

A homeless man faces Wall Street

Spencer Platt/Getty Images
Politics & Current Affairs
  • A recently published study suggests that some welfare programs more than pay for themselves.
  • It is one of the first major reviews of welfare programs to measure so many by a single metric.
  • The findings will likely inform future welfare reform and encourage debate on how to grade success.
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