Connect with us
https://tpc.googlesyndication.com/pagead/imgad?id=CICAgKDriYHe3QEQARgBMgh47LykQhqW-w

Space

Our Universe Isn't As Special As We'd Like to Believe

Space.com

Published

on

Humans like to be at the center of things.

The early Greeks knew the Earth was round, but most of them could not imagine that the land they walked on was anything but the dead center of reality. Maimonides, the medieval Spanish-Egyptian Jewish philosopher, took that geocentrism to heart, arguing that even the ancient Hebrew Bible described a world where everything revolved around our planet — a position that Rabbi Menachem Mendel Schneerson, the Lubavitcher Rebbe, defended using Albert Einstein’s theory of relativity as recently as 1975. It took more than 350 years for the Catholic Church to apologize (in 1992!) for imprisoning the great heliocentrist astronomer Galileo Galilei and forcing him to recant his description of the solar system.

In the modern era, no serious thinker argues that the Earth has some special physical centrality in the universe. (Schneerson’s paper claimed only that the Earth could be seen as the center of the universe from a particular reference frame.) All the evidence of the great telescopes has shown that Earth is just another small, rocky world orbiting a smallish sun in a far-flung region of a medium-size galaxy.

But there’s another idea out there, popular among some of the greatest scientists alive, that centers humans (and creatures like us) to an extent that the ancient philosophers couldn’t have imagined. It’s so outlandish that Maimonides would likely have considered it a heresy, a violation of his principle that God and only God willed the universe into being. [Creationism vs. Evolution: 6 Big Battles]

Here’s how it goes:

The universe is perfect — eerily, uncannily perfect— as a setting for creating life. All sorts of physical constants — the speed of light, the charge of an electron, the ratios of the four fundamental forces (gravity, electromagnetism, weak and strong) — seem fine-tuned to create a universe where life as we know it could emerge.

Here’s how the writer Anil Ananthaswamy explained one example for PBS:

“[The neutron] is 1.00137841870 times heavier than the proton [a bare hydrogen nucleus], which is what allows it [a neutron] to decay into a proton, electron and neutrino — a process that determined the relative abundances of hydrogen and helium after the Big Bang and gave us a universe dominated by hydrogen. If the neutron-to-proton mass ratio were even slightly different, we would be living in a very different universe: one, perhaps, with far too much helium, in which stars would have burned out too quickly for life to evolve, or one in which protons decayed into neutrons rather than the other way around, leaving the universe without atoms. So, in fact, we wouldn’t be living here at all — we wouldn’t exist.”

That is, even as tiny a number as the mass of a neutron — the subatomic particle inside all atomic nuclei except that of hydrogen — is perfectly calibrated to allow worlds like Earth to emerge and survive over long spans. This, the thinking goes, is evidence that our universe exists only because there are thinking beings here to observe it.

The idea has some relation to a basic principle of the world of the very small: According to quantum mechanics, a particle takes on a particular speed or a particular location only because someone observed it. Before it was observed, the particle just had a range of possible speeds or locations in space.

Perhaps a universe pops into full existence only when its physical constants are just such that they might be observed?

It’s a strange and radical way of thinking about this vast space and our place in it. But it’s not a fringe idea.

“The remarkable fact is that the values of [fundamental physics] numbers seem to have been very finely adjusted to make possible the development of life,” the physicist Stephen Hawking wrote in his 1988 book “A Brief History of Time.” [8 Shocking Things We Learned from Stephen Hawking’s Book]

“For example,” he went on, “if the electric charge of the electron had been only slightly different, stars either would have been unable to burn hydrogen and helium, or else they would not have exploded. Of course, there might be other forms of intelligent life, not dreamed of even by writers of science fiction, that did not require the light of a star like the sun or the heavier chemical elements that are made in stars and are flung back into space when the stars explode.

“Nevertheless, it seems clear that there are relatively few ranges of values for the numbers that would allow the development of any form of intelligent life. Most sets of values would give rise to universes that, although they might be very beautiful, would contain no one able to wonder at that beauty.”

The universe might very well exist only so that we, and creatures like us, might live to see it. Even Hawking suggests the possibility.

But not everyone is convinced.

In a new paper made available Jan. 18 at the preprint website arXiv.org, a team of University of Michigan astronomers and physicists made the case that even a vastly different universe might support life.

Starting from physical principles, the researchers worked out how a universe might develop with one of its fundamental forces amputated entirely.

Remember the weak force mentioned above?

It’s got the least impressive name of the four fundamentals, but it by no means played a minor part in how our universe came together. As Live Science previously reported, weak is the force of decay. When big particles fall apart into small particles, it’s not because the strong force holding them together has failed. Rather, the weak force has forced them apart.

“I would say that the weak force is most important in the sun [and other stars],” said Evan Grohs, one of the authors of the arXiv paper.

When the hot mass of a burning star forces two protons — bare hydrogen nuclei — together, Grohs told Live Science, they fuse into a hydrogen isotope called a deuteron (along with some spare particles). This is a weak force interaction. The deuteron then fuses with another free proton to form a nucleus of two protons and one neutron (which is also known as helium-3). That’s an electromagnetic interaction. Finally, the strong force brings that helium-3 particle together with another helium 3, forming a helium-4 nucleus and two free protons. Without the weak force, that chain of events couldn’t happen, and the sun would quickly burn itself out.

Similarly, the weak force is responsible for the abundance of water in the universe, Grohs said, a feature generally thought necessary for life.

During and shortly after the Big Bang, the weak force caused free neutrons to decay into single protons — loose hydrogen nuclei floating free in the universe. Just about all the hydrogen around today is a result of those weak-force interactions during the Big Bang era, Grohs said. And their abundance is necessary for the formation of water, with its two hydrogen atoms to each oxygen atom.

If a universe formed that was otherwise entirely like ours, but missing the weak force, just about all the free neutrons and protons would fuse together into helium in the few moments after the universe emerged, according to Grohs.

But Grohs and his colleagues, in their paper, imagined a “weakless” universe with some other key parameters changed. Their universe, they showed, would still seem to meet all the known requirements for life. [Top 5 Reasons We May Live in a Multiverse]

First, their universe would begin with way more photons (that is, light) than matter particles screaming into space — reducing the ratio of starting matter to energy by a factor of at least 100 compared to our universe, the researchers said. Out of that high-energy, low-matter particle cloud, they calculated, would emerge a mix of protons, free neutrons, deuterium (another hydrogen isotope) and helium similar to the one in our universe.

And then, for a long time, whatever alien god created this weakless place could just sit back and wait. The weak force acts on tiny scales, affecting the behaviors of elementary particles. So, in this other universe, with the large-scale forces of gravity and electromagnetism intact, clouds of matter would still form galactic discs and condense into stars, the researchers showed. There would be some differences, the scientists found — most importantly, an unusual abundance of deuterium resulting from all those free protons and neutrons floating around. However, nothing would upset the basic structure of space.

Finally, when it came time to light up the stars, the alien god should look closely. Without a weak force in this oddball universe, hydrogen wouldn’t fuse into helium. But there would be a lot of deuterium there, and deuterium lights up the darkness in its own way.

Smash a free proton into deuterium, and the strong force will bind the two particles together in a flash of energy, leaving behind the heavy helium isotope helium-3.

This deuterium fusion burns less brightly than the weak-force process that occurs in our sun. Most of the stars in the alternate universe would form into something like our red giants: big and dim and gone in just a short span of time.

But some stars that would burn longer, some more than a billion years. And that’s critical.

“We don’t have any other examples of life besides this planet,” Grohs said, and on this planet, life took about a billion years to form. There’s no reason, Grohs said, to assume it would take any more (or less) time in his weakless other place. That means you would likely need these long-lasting stars for life to take root, he said.

So, what would it be like to walk around on a planet orbiting in weakless space?

“I think one thing you would notice is that you probably wouldn’t have as many solid structures, because you’re not going to have those heavy Earth elements like you have on our planet,” Grohs told Live Science.

In the weakless universe, as in ours, stars would be chemical factories. As the stars aged, they would fuse more and more protons onto their heaviest particles, building heavier elements. In our universe, this process goes pretty far, building plenty of oxygen and carbon, but also heavy iron and even a significant amount of superheavy radioactive elements like uranium.

But in the weakless universe, without neutron decay, strong-force fusion would mostly run out of steam at around the level of nickel, a relatively light element, with just 28 protons. Heavier atoms — like iron, gold, iodine and xenon — might still emerge, but in much smaller quantities, Grohs said.

Lighter chemicals, like oxygen and carbon, Grohs said, would be much more abundant.

Still, he added, “I think if you were on a planet in a weakless universe, it would be fairly similar. The stars might be a little larger if you looked into the sky, because in order to have a star that burns deuterium for billions of years, it needs to actually physically have a larger radius than an equivalent star in our universe, and in addition, it doesn’t shine as brightly.”

So, a life-supporting planet in a weakless universe would likely be much closer to its much-larger star, a big, unusually dim disc taking up a large fraction of the sky.

Grohs acknowledged that the research is fundamentally speculative.

“This is all theoretical,” he said. “We don’t have any evidence to suggest that there are other universes beyond what we can see.”

And the questions he and his colleagues answer — whether an alien universe could have water or structure or long-lasting stars — might not be an exhaustive list of factors necessary to produce life, he said. And a weakless universe might not even be the best candidate for an alternative universe that might produce life.

Still, Grohs said, this paper throws a wrench in the argument that there’s something special or necessary about the life-giving physical constants of our universe. And it raises the real possibility that our perception just isn’t at the center of things at all.

Originally published on Live Science.

Space.com is the premier source of space exploration, innovation and astronomy news, chronicling (and celebrating) humanity's ongoing expansion across the final frontier. We transport our visitors across the solar system and beyond through accessible, comprehensive coverage of the latest news and discoveries. For us, exploring space is as much about the journey as it is the destination. So from skywatching guides and stunning photos of the night sky to rocket launches and breaking news of robotic probes visiting other planets, at Space.com you’ll find something amazing every day.

Advertisement

Space

'Stargate Origins' Brings Classic Sci-Fi Back Tonight

Space.com

Published

on

Continue Reading

Space

Mars Meteorite Will Return to the Red Planet with NASA Rover

Space.com

Published

on

Rohit Bhartia of NASA’s Mars 2020 mission holds a slice of a meteorite scientists have determined came from Mars. This slice will likely be used here on Earth for testing a laser instrument for NASA’s Mars 2020 rover; a separate slice will go to Mars on the rover.

A chunk of rock that was once part of Mars, but landed on Earth as a meteorite, will return to the Red Planet aboard a NASA rover set to launch in 2020

The meteorite, known as Sayh al Uhaymir 008 (SaU008) was found in Oman in 1999, but geologists determined that it likely originated on Mars, according to a statement from NASA’s Jet Propulsion Laboratory. Scientists think collisions between Mars and other large bodies in the solar system’s early days sent chunks of the Red Planet into space, where they might wander for eons before falling onto Earth’s surface.  

Now, NASA scientists are using the meteorite to calibrate an instrument that will fly on the Mars 2020 rover, which is scheduled to drop down on the Red Planet’s surface and collect rock samples that could one day be returned to Earth. One of the rover’s main goals is to evaluate the potential habitability of ancient and present-day Mars. [How NASA’s Mars 2020 Rover Will Work (Infographic)]

The meteorite is being used to calibrate an instrument called the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals), which will use techniques often used in forensic science to identify chemicals in the Martian rock samples, in features as thin as a human hair.

A close-up of a meteorite that likely came from Mars.

A close-up of a meteorite that likely came from Mars.

Credit: NASA/JPL-Caltech

The researchers will study the meteorite on Earth, where they are able to make sure their instruments are producing a correct analysis of the rock, and understand what features of the rock are perceptible to their instruments. When the rover settles onto Mars, researchers can once again use the rock to make sure their instruments are working as they should be, before pointing them at features of the Martian surface. 

“We’re studying things on such a fine scale that slight misalignments, caused by changes in temperature or even the rover settling into sand, can require us to correct our aim,” said Luther Beegle, principal investigator for SHERLOC, in the statement. “By studying how the instrument sees a fixed target, we can understand how it will see a piece of the Martian surface.”

There are only about 200 confirmed Martian meteorites that have been found on Earth, according to the statement. The SaU008 meteorite comes from London’s Natural History Museum, which lends out hundreds of meteorites (most of them not from Mars) every year for scientific studies. The SHERLOC team needed a Martian meteorite that was robust enough to endure the journey to Mars without flaking or crumbling. (Launch from Earth and entry into the Martian atmosphere are both very strenuous events for everything on board.) The rock also “needed to possess certain chemical features to test SHERLOC’s sensitivity. These had to be reasonably easy to detect repeatedly for the calibration target to be useful,” according to the statement.  

A slice of a Martian meteorite undergoes oxygen cleaning to remove organics. This slice will remain on Earth to be used for testing and calibrating instruments.

A slice of a Martian meteorite undergoes oxygen cleaning to remove organics. This slice will remain on Earth to be used for testing and calibrating instruments.

Credit: NASA/JPL-Caltech

Usually, instruments like SHERLOC are calibrated with a variety of materials including rock, metal and glass. And Mars meteorites have been used for instrument calibration in the past. In fact, another instrument aboard the Mars 2020 rover, called SuperCam, will be adding a Mars meteorite to NASA’s calibration target, according to the statement. And while this would be the first Mars meteorite to return to the surface of the Red Planet, NASA’s Mars Global Surveyor, which orbits the Red Planet, carries a chunk of a Martian meteorite.

SHERLOC will carry other materials from Earth in addition to Su008, including materials that could be used to make a spacesuit for use on Mars. Observations of how the material withstands the radiation, atmosphere and temperature variations on Mars will provide valuable information for possible crewed trips to the Red Planet.  

“The SHERLOC instrument is a valuable opportunity to prepare for human spaceflight as well as to perform fundamental scientific investigations of the Martian surface,” Marc Fries, a SHERLOC co-investigator and curator of extraterrestrial materials at Johnson Space Center, said in the statement. “It gives us a convenient way to test material that will keep future astronauts safe when they get to Mars.”

Follow Calla Cofield @callacofield. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

Continue Reading

Space

Kepler Space Telescope Discovers 95 More Alien Planets

Space.com

Published

on

Planets around other stars are the rule rather than the exception, and there are likely hundreds of billions of exoplanets in the Milky Way alone. NASA’s Kepler space telescope has found more than 2,400 alien worlds, including a new haul of 95 planets announced on Feb. 15, 2018.

The exoplanet discoveries by NASA’s Kepler space telescope keep rolling in.

Astronomers poring through data gathered during Kepler’s current extended mission, known as K2, have spotted 95 more alien planets, a new study reports. 

That brings the K2 tally to 292, and the total haul over Kepler’s entire operational life to nearly 2,440 — about two-thirds of all the alien worlds ever discovered. And more than 2,000 additional Kepler candidates await confirmation by follow-up observations or analysis. [7 Greatest Exoplanet Discoveries by NASA’s Kepler (So Far)]

Kepler launched in March 2009, on a mission to help scientists determine just how common rocky, potentially habitable worlds such as Earth are throughout the Milky Way. For four years, the spacecraft stared continuously at about 150,000 stars, looking for tiny dips in their brightness caused by the passage of planets across their faces.

This work was highly productive, as noted above. But in May 2013, the second of Kepler’s four orientation-maintaining “reaction wheels” failed, and the spacecraft lost its superprecise pointing ability, bringing the original mission to a close.

But mission managers figured out a way to stabilize Kepler using sunlight pressure, and the spacecraft soon embarked on its K2 mission, which involves exoplanet hunting on a more limited basis, as well as observing comets and asteroids in our own solar system, supernovas and a range of other objects and phenomena.

For the new study, researchers analyzed K2 data going all the way back to 2014, zeroing in on 275 “candidate” signals.

“We found that some of the signals were caused by multiple star systems or noise from the spacecraft,” study lead author Andrew Mayo, a Ph.D. student at the Technical University of Denmark’s National Space Institute, said in a statement. “But we also detected planets that range from sub-Earth-sized to the size of Jupiter and larger.”

Indeed, 149 of the signals turned out to be caused by bona fide exoplanets, 95 of which are new discoveries. And one of the new ones is a record setter.

“We validated a planet on a 10-day orbit around a star called HD 212657, which is now the brightest star found by either the Kepler or K2 missions to host a validated planet,” Mayo said. “Planets around bright stars are important because astronomers can learn a lot about them from ground-based observatories.”

The new study was published today (Feb. 15) in The Astronomical Journal.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

Continue Reading

Space

Russian Cargo Ship Delivers 3 Tons of Supplies to Space Station

Space.com

Published

on

Continue Reading

Tags

Trending