In space, no one can hear you scream. An infinite universe can mean infinite possibilities, some of which can be quite spooky. We are not talking about ghosts and zombies, but of asteroids, comets and dead stars.
Surely a guide could help us find the way among all these horrors. Luckily, we’ve got the perfect team for it. We brought in Josh Colwell, Addie Dove, Jim Cooney and Audrey Martin – they are physicists at the University of Central Florida and hosts of the podcast Walkabout the Galaxy. They came to warn us about the spookiest things our universe has to offer.
The sky is falling
Watching the stars at night can be one of the most incredible experiences one can have. But what if some of them get a bit too close?
Every year the Earth is bombarded by thousands of dust sized objects. But, as the size of these objects increases, so does their destructive power.
“It’ll ruin your day,” Colwell said. “If an asteroid that's the size of a football stadium comes in, that has about 50 megatons of TNT equivalent. So, about 1000 times the destructive energy of the Hiroshima atomic bomb.”
Luckily, our ability to monitor these potentially hazardous asteroids is quite effective.
Comets on the other hand can be a lot more unpredictable – they release gases as they enter the inner solar system which could alter their trajectory.
A devilish comet
Every 70 or so years, comet Pons-Brooks returns and for the most part it’s quite normal as far as comets go, with one exception: it has devil horns! Thankfully, we don’t need to worry about any supernatural risks, as there is a very simple explanation for these horns: ice volcanoes.
“There's an area on the surface of Pons-Brooks that is obstructed or is really, really strong,” explained Martin. That prevents the comet from expelling gas, leaving blank spaces that are “essentially what looks like two tails, but the two tails look just like devil horns.”
The next time the comet will be the closest to us will be between spring and summer 2024, although it is possible it might be very faint.
Monsters of the cosmos
For many years black holes were just a hypothesis, but recently many new discoveries have changed our understanding of this cosmic phenomenon. Black holes are remnants of supermassive stars that exploded, leaving behind what is known as a “singularity." These objects have an incredibly strong gravitational pull, so strong that nothing can escape it, not even light. Addie Dove said one kind of black hole is particularly scary: rogue ones.
“There's been theories for a while that black holes can actually be ejected from the center of the galaxies in which they've been formed, and just be sort of rogue in the universe," Dove said. "And they're basically then undetectable, because they don't have enough material around them.”
One of these black holes has been detected to be just 1.58 kilo parsecs away from us, which is about 300 million times the distance from the Sun and the Earth.
Death of the universe
What is the world going to look like in 100 years? What about in 100 millennia? 100 billion years? Well, eventually every star will burn up all its fuel, and there won’t be enough cosmic dust to make new ones, so the age of light in our universe will come to an end.
Given enough time, the universe will eventually reach a state of thermodynamic equilibrium, where all things reach the same temperature and stop.
"It turns out when that happens, and that temperature is very, very low, nothing interesting can happen anymore,” explained Cooney. “All of the interesting fun processes that happen in physics, work that's being done, exchanges of energy, all that happened because we're not in equilibrium. With equilibrium nothing can ever happen here.”
