Physics

"Cosmic strings" may have stopped the universe from destroying itself

"Cosmic strings" may have stop...
A simulated image of cosmic strings
A simulated image of cosmic strings
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A timeline of events from the Big Bang, through phase transition, to the creation of the cosmic strings, the birth of the cosmic microwave background, and finally, the present day
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A timeline of events from the Big Bang, through phase transition, to the creation of the cosmic strings, the birth of the cosmic microwave background, and finally, the present day
A simulated image of cosmic strings
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A simulated image of cosmic strings

The Big Bang theory explains how the universe came to be – but, ironically, if followed to the letter it also suggests that we shouldn’t exist today. That’s because equal amounts of matter and antimatter should have been created, which would just have annihilated each other. But now, physicists have proposed a new theory that explains the mystery – and outlined how we can find direct evidence of it.

Everything around us – and in us – is made of matter. Antimatter, on the other hand, seems to be extremely rare, produced briefly in experiments at CERN or during lightning storms and hurricanes.

But we should be thankful for that rarity. Antimatter particles have the opposite electrical charge to matter, and if ever the two should meet they’ll destroy each other in a burst of energy. That could be handy for future space travel, but it also suggests that such a voyage would be pretty dull, since everything in the universe would have completely annihilated itself over time.

The fact that we’re here questioning this right now means that obviously, that didn’t happen. But why? By all accounts the Big Bang should have produced matter and antimatter in equal amounts, so where did all the antimatter go? And why did matter win what should have been an evenly-matched war? Those are some of the biggest unanswered questions in cosmology.

Our own existence suggests that somehow, at some point in time, some antimatter must have turned into regular matter. Even if the imbalance is as tiny as one part in a billion, that could leave enough matter behind after all the annihilation to make the stars, galaxies, planets, people and pizza that we see today.

The problem is that matter and antimatter can’t just swap teams easily, since they have opposite electrical charges. All except the neutrino – these tiny, fundamental particles are the only ones we know of that have a neutral electric charge. Since the opposite of zero is still zero, neutrinos could be their own antiparticles. That means that neutrinos could have switched sides, with a little help from the universe undergoing a phase transition.

“A phase transition is like boiling water to vapor, or cooling water to ice,” says Hitoshi Murayama, co-author of the study. “The behavior of matter changes at specific temperatures called critical temperature. When a certain metal is cooled to a low temperature, it loses electrical resistance completely by a phase transition, becoming a superconductor. Just like a superconductor, the phase transition in the early universe may have created a very thin tube of magnetic fields called cosmic strings.”

According to some theories, these cosmic strings permeate the universe, kind of like how cracks might form in ice as the water freezes. They could have given neutrinos the kick needed to change electrical charges – but so far no direct evidence of these strings has ever been found.

That could be because they’re hiding further back in time than we can see. It’s thought that cosmic strings would have formed relatively quickly after the phase transition, and this would all have taken place within the first million years or so of the universe’s existence.

A timeline of events from the Big Bang, through phase transition, to the creation of the cosmic strings, the birth of the cosmic microwave background, and finally, the present day
A timeline of events from the Big Bang, through phase transition, to the creation of the cosmic strings, the birth of the cosmic microwave background, and finally, the present day

Unfortunately, light only allows our telescopes to look back about this far before background radiation washes everything out. But there is another way to study what happened before then – gravitational waves. These ripples in the very fabric of spacetime are given off by huge cataclysms like black holes merging, and we’ve been detecting them pretty consistently since 2015.

According to the researchers on the new study, these cosmic strings may also have left gravitational imprints on spacetime, which we could detect. Granted, they’d be much smaller than the ones we currently find with LIGO and other instruments, but they’d also look very different, allowing scientists to tell them apart.

“The recent discovery of gravitational waves opens up a new opportunity to look back further in time, as the universe is transparent to gravity all the way back to the beginning,” says Graham White, co-author of the study. “When the universe might have been a trillion to a quadrillion times hotter than the hottest place in the universe today, neutrinos are likely to have behaved in just the way we require to ensure our survival. We demonstrated that they probably also left behind a background of detectable gravitational ripples to let us know.”

The researchers say that future space-based gravitational wave detectors, such as LISA, BBO or DECIGO, could help us hunt down these cosmic strings and solve the mystery once and for all.

The research was published in the journal Physical Review Letters.

Source: Kavli IPMU

7 comments
Jerome Morley Larson Sr eAIA
Or, perhaps, there is no such thing as anti matter because there is no such thing as gravity — everything exists because it is constantly expanding from the force of time; big stuff like Earth expands faster than small stuff like me so I feel a force pushing me up — we say things fall same as we say the sun sets but we ignore the fact that all things fall at the same rate so to build up the weirdest theories on gravity and the universe expansion when the real is hiding in plain sight — its all just time working its magic.
buzzclick
More prognosticating and speculation. We humans are finite creatures, and consequently, people believe that the Universe is 13.5 billion years old and has a birth, like we do. I believe that the Cosmos is all there is, and all it ever will be, with no beginning or ending. There are countless energies out there interacting, and it's a marvelous macrocosm of our earthly existence. Male and female, yin and yang, hot and cold, positive and negative, wet and dry, night and day...it's all relative. It always astounds me to think that the gravitational power of our sun can affect the orbit of Pluto which is a mind-boggling 3.6 billion miles away! Of course there are cosmic strings out there. It's presumptuous to think that matter and anti-matter would just annihilate each other when they could easily have neutralized each other. Einstein's speculation that time is slowed down the closer we get to the speed of light is hogwash because it cannot be proven. It is impossible to travel to the past and the future. It's just a sci-fi fantasy, and we humans are full of them.
lucius
How cool is that? The Flying Spaghetti Monster is real and created all the matter in the universe! https://en.wikipedia.org/wiki/Flying_Spaghetti_Monster
buzzclick
Yo Lucius, that is too funny. I had heard (and forgotten) about Pastafarians and the Church of the FSM. Had me in stitches. As a child growing up in Orthodox Christianity, I have come to realize as an adult that all religions, however solemn and significant they're found to be, cannot be proven. It's blind faith. It's a lifestyle choice. If you wanna believe in Pasta Creationism, it's your prerogative. The church and state should be separate. If people are free to choose to believe their dogma, anyone can practice in whatever devotion they desire. The absurdity (or reality), no matter how offensive one finds it to be, should not and cannot be allowed to have it declared as verboten. Blessed are those who believe in the Flying Spaghetti Monster!
Rotogizmag
Yes, and Micky Mouse may have created Disneyland. Since none are real, equally likely.
ljaques
I want a print of that Cosmic String picture for my living room wall. Pretty cool. And I won't bore you with the reality these folks have missed in their theories. ;)
amazed W1
Hm, hm. Looks like we should reintroduce the theory that much explains itself if we accept plasma fields and forces between moving plasmas?? A certain professor would have to be "rehabilitated" by those of his peers who are still with us but at least a rational argument could be initiated..