Will the Universe End Will the Universe Begin Again

May 15, 2022 Post a Comment

The Beginning to the Stop of the Universe: The Big Crisis vs. The Big Freeze

Astronomers once thought the universe could plummet in a Big Crunch. At present most hold it volition end with a Large Freeze.

This story comes from our special Jan 2021 result, "The Start and the End of the Universe." Click here to purchase the full result.

How will the universe cease? Humanity has pondered this question for thousands of years. And now science actually has the cognition and tools to attempt an answer.

Until rather recently, astronomers thought the cosmos would repeatedly expand and plummet in an space bicycle of cosmic death and rebirth. But the best evidence points to a distant Armageddon filled with more existential dread than the Book of Revelation. Trillions of years in the time to come, long subsequently World is destroyed, the universe will migrate apart until galaxy and star formation ceases. Slowly, stars will fizzle out, turning night skies black. All lingering matter will be gobbled up by black holes until in that location'southward nothing left. Finally, the last traces of heat will disappear.

Rather than coming together its end through burn and brimstone, the creation will probable succumb to "heat death." Astronomers call information technology the Big Freeze.

Alpha and Omega

The universe didn't ever seem destined to cease this way. Roughly a century ago, astronomers thought that our Galaxy Galaxy was the entire universe. Our cosmos appeared static — it had always been, and would always remain, roughly the same. However, every bit Albert Einstein formulated his theories of relativity, he noticed signs of something strange. His equations implied a universe in motion, either expanding or contracting. Then Einstein added a fudge gene — a cosmological constant — that held the universe in a more appealing steady state.

"Einstein was not being stupid; he was feeling the feeling of astronomers," says Nobel Prize-winning cosmologist John Mather, the head scientist for NASA's James Webb Space Telescope.

Nonetheless, around the same time, astronomers began to accept that some of the fuzzy screw-shaped nebulae they observed through their telescopes were not collections of stars in our galaxy. They were other galaxies entirely. And when Edwin Hubble meticulously measured their motions, he showed these galaxies were indeed moving away from our ain. Humanity had discovered that the universe is expanding.

Pressing rewind on that expansion ultimately revealed that the entire universe was built-in in a violent Large Bang some 13.8 billion years agone. With its foundations firmly fixed, cosmology turned to the next bully question: How will the universe finish?

At that place are two primary ways for an expanding universe to die: The cosmos could eventually collapse back in on itself, or it could continue inflating forever. To find out which is right, astronomers had to fast-frontwards the development of the universe.

The Big Crunch

In 1922, Russian physicist and mathematician Alexander Friedmann derived a famous set of equations aptly named the Friedmann equations. These calculations showed that our universe's destiny is determined by its density, and it could either aggrandize or contract, rather than remain in a steady country. With plenty matter, gravity would eventually halt the cosmos' expansion, causing it to come crashing back inwards.

In the 1960s and 1970s, when astronomers added up all the matter in the known universe, they calculated at that place was plenty mass that the creation should ultimately plummet to an infinitely dense state, or mayhap even a gargantuan black hole.

Some speculated that once compressed into an infinitely small-scale point — the Big Crisis — the universe would kickstart yet another expansion, or Large Bounce.

In the 1970s and 1980s, physicist John Wheeler, who helped coin the term black pigsty, became a leading proponent of the Big Crunch. To him, it was an obvious fate. A revolution in understanding black holes was underway, and Wheeler saw each ane as an "experimental model" of the universe's terminal state.

But Wheeler's Big Crunch fondness was partially born from aesthetics, he admitted. It was easy to pic.

The Large Freeze

Unfortunately, reality is not always and so relatable.

"Just because we might find a common cold, empty universe an unappealing futurity doesn't hateful that that's not where things are headed," Columbia University physicist Peter Woit writes on his web log, Not Fifty-fifty Wrong.

In the belatedly 1990s, ii carve up groups of scientists were surveying the distant universe, studying dying stars called type Ia supernovae, which serve as standard candles that help establish cosmic distances. They constitute distant blasts appeared dimmer, and were therefore farther abroad, than expected. The universe'southward expansion wasn't slowing down at all — it was speeding upwards. The teams had independently stumbled onto dark energy, shattering existing models of the universe. (See "The mystery of nighttime free energy," page 53.)

The expectation-defying discovery of night energy showed the universe was very unlikely to collapse in a Big Crunch. Even with all the matter in the universe tugging inward, gravity volition never be strong enough to overcome the inflating effect of dark free energy. In other words, the ballooning universe is destined for a Large Freeze.

These days, astronomers recall normal matter comprises just 5 percent of the universe'south contents. Meanwhile, dark thing makes up some 26 pct, and dark free energy accounts for the final 69 per centum. Dark energy, it turns out, seems to exist the real-earth force backside Einstein's cosmological abiding, which plays a major part in preventing a Big Crisis-style collapse.

Thanks to the expansion acquired past night energy, within a couple of trillion years, all but the closest galaxies will exist too far away to see. Then, possibly 100 trillion years later, star formation will cease, as dumbo stellar remnants like white dwarfs and black holes lock up any remaining material.

Well-nigh a googol years from now — that'south a 1 followed by 100 zeroes — the terminal objects in the universe, supermassive black holes, will finish evaporating via Hawking radiation. Later on this, the universe enters a so-chosen Dark Era, where matter is just a distant memory.

The second law of thermodynamics suggests that entropy volition keep increasing in a system (such as the creation) until it hits a maximum level. In existent terms, that ways that at some point, the universe will ultimately reach a land where all energy — and, hence, rut — is uniformly distributed. The final temperature of the entire universe volition hover a smidge to a higher place accented zero.

So, rather than mirroring Revelation, the death of our cosmos will likely resemble the get-go of Genesis: All will exist empty and dark.

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Source: https://astronomy.com/news/magazine/2021/01/the-beginning-to-the-end-of-the-universe-the-big-crunch-vs-the-big-freeze#:~:text=There%20are%20a%20few%20ways,ll%20face%20a%20Big%20Freeze.