Posted on by Fraser Cain

What are White Holes?

What are White Holes?

Black holes are created when stars die catastrophically in a supernova. So what in the universe is a white hole?

It’s imagination day, and we’re going to talk about fantasy creatures. Like unicorns, but even rarer. Like leprechauns, but even more fantastical!

Today, we’re going to talk about white holes. Before we talk about white holes, let’s talk about black holes. And before we talk about Black Holes, what’s is this thing you have with holes exactly?

Black holes are places in the Universe where matter and energy are compacted so densely together that their escape velocity is greater than the speed of light. We’ve done at least a million videos on them, but if you still want more info, you can start here with our Black Hole playlist.

Fully describing a black hole requires a lot of fancy math, but these are real objects in our Universe. They were predicted by Einstein’s theory of relativity, and actually discovered over the last few decades.

Black holes are created when stars, much more massive than our Sun, die catastrophically in a supernova.
So then what’s a white hole?

White holes are created when astrophysicists mathematically explore the environment around black holes, but pretend there’s no mass within the event horizon. What happens when you have a black hole singularity with no mass?

White holes are completely theoretical mathematical concepts. In fact, if you do black hole mathematics for a living, I’m told, ignoring the mass of the singularity makes your life so much easier.

They’re not things that actually exist. It’s not like astronomers detected an unusual outburst of radiation and then developed hypothetical white hole models to explain them.

White Hole
White Hole. Image Credit: universe-review.ca

As my good friend and sometimes Guide to Space contributor, Dr. Brian Koberlein says, “If you start with five cupcakes and start giving them away, you eventually run out. At that point you can’t give away any more. In this case you can’t count down past zero. Sure, you can hand out slips of paper with “I O U ONE cupcake.” written on them, but it would be ridiculous to use the existence of negative numbers to claim that “negative cupcakes” exist and can be handed out to people.”

Now if white holes did exist, which they probably don’t, they would behave like reverse black holes – just like the math predicts. Instead of pulling material inward, a white hole would blast material out into space like some kind of white chocolate fountain. So generous, these white holes and their chocolate.

One of the other implications of white hole math, is that they only theoretically exist as long as there isn’t a single speck of matter within the event horizon. As soon as single atom of hydrogen drifted into the region, the whole thing would collapse. Even if white holes were created back at the beginning of the Universe, they would have collapsed long ago, since our Universe is already filled with stray matter.

That said, there are a few physicists out there who think white holes might be more than theoretical. Hal Haggard and Carlo Rovelli of Aix-Marseille University in France are working to explain what happens within black holes using a branch of theoretical physics called loop quantum gravity.

Artistic view of a radiating black hole. Credit: NASA
Artistic view of a radiating black hole. Credit: NASA

In theory, a black hole singularity would compress down until the smallest possible size predicted by physics. Then it would rebound as a white hole. But because of the severe time dilation effect around a black hole, this event would take billions of years for even the lowest mass ones to finally get around to popping.

If there were microscopic black holes created after the Big Bang, they might get around to decaying and exploding as white holes any day now. Except, according to Stephen Hawking, they would have already evaporated.

Another interesting idea put forth by physicists, is that a white hole might explain the Big Bang, since this is another situation where a tremendous amount of matter and energy spontaneously appeared.

In all likelihood, white holes are just fancy math. And since fancy math rarely survives contact with reality, white holes are probably just imaginary.

What other highly theoretical theories in space and physics would you like us to investigate? Tell us in the comments below.

Posted on by Fraser Cain

Is Jupiter Our Friend Or Enemy?

Is Jupiter Our Friend Or Enemy?

Like me, you’re probably a little ego-geocentric about the importance of Earth. It’s where you were born, it’s where you keep all your stuff. It’s even where you’re going to die – I know, I know, not you Elon Musk, you’re going to “retire” on Mars, right after you nuke the snot out of it.

For the rest of us, Earth is the place. But in reality, when it comes to planets, this is somebody else’s racket. This is Jupiter’s Solar System, and we all sleep on its couch.

Jupiter accounts for 75% of the mass of the planets of the Solar System, nearly 318 times more massive than Earth, and isn’t just the name of everyone’s favorite secret princess. It’s the 1.9 × 10^27 kilogram gorilla in the room. Whatever Jupiter wants, Jupiter gets. Jupiter hungry? JUPITER HUNGRY.

What Jupiter apparently wants is to throw our stuff around the Solar System. Thanks to its immense gravity, Jupiter yanks material around in the asteroid belt, preventing the poor space rocks from ever forming up into anything larger than Ceres.

Jupiter gobbles up asteroids, comets, and spacecraft, and hurtles others on wayward trajectories. Who knows how much mayhem and destruction Jupiter has gotten into over the course of its 4.5 billion years in the Solar System.

Some scientists think we owe our existence to Jupiter’s protective gravity. It greedily vacuums up dangerous asteroids and comets in the Solar System.

Other scientists totally disagree and think that Jupiter is a bully, perturbing perfectly safe comets and asteroids into dangerous trajectories and flushing earth’s head in the toilet during recess.

Which is it? Is Jupiter our friend and protector, or evil enemy. We’ve already figured out how to dismantle you Jupiter, don’t make us put our plans into action.

Some of the most dangerous objects in the Solar System are long-period comets. These balls of rock and ice come from the deepest depths of the Oort cloud. Some event nudges these death missiles into trajectories that bring them into the inner Solar System, to shoot past the Sun and maybe, just maybe, smash into a planet and kill 99.99999% of the life on it.

The Solar System. Credit: NASA
The Solar System. Credit: NASA

There’s a pretty good chance some of the biggest extinctions in the history of the Earth were caused by impacts by long period comets.

As these comets make their way through the Solar System, they interact with Jupiter’s massive gravity, and get pushed this way and that. As we saw with Comet Shoemaker-Levy, some just get consumed entirely, like a tasty ice-rock sandwich.

The theory goes that Jupiter pushes these dangerous comets out of their murder orbits so they don’t smash into Earth and kill us all.

But a competing theory says that Jupiter actually diverts comets that would have completely missed our planet into deadly, Earth-killing trajectories.

Will the Sailor Scouts provide us any clues? Who can say?

Fragmentation of comets is common. Many sungrazers are broken up by thermal and tidal stresses during their perihelions. At top, an image of the comet Shoemaker-Levy 9 (May 1994) after a close approach with Jupiter which tore the comet into numerous fragments. An image taken by Andrew Catsaitis of components B and C of Comet 73P/Schwassmann–Wachmann 3 as seen together on 31 May 2006 (Credit: NASA/HST, Wikipedia, A.Catsaitis)
At top, an image of the comet Shoemaker-Levy 9 (May 1994) after a close approach with Jupiter which tore the comet into numerous fragments. An image taken by Andrew Catsaitis of components B and C of Comet 73P/Schwassmann–Wachmann 3 as seen together on 31 May 2006 (Credit: NASA/HST, Wikipedia, A.Catsaitis)

Here’s friend of the show, Dr. Kevin Grazier, a planetary scientist and scientific advisor for many of your favorite sci-fi TV shows and movies.

… [ see video for Interview with Dr. Grazier about Jupiter]

So which is it? Is Jupiter our friend or enemy? We’ll need to run more simulations and figure this out with more accuracy. And until then, it’s probably best if we just tremble in fear and worship Jupiter as a dark and capricious god until the evidence proves otherwise. It’s what Pascal would wager.

What are some other theories you’ve heard about and you’d like us to dig in further? Make some suggestions in the comments below.

Thanks for watching! Click subscribe, never miss an episode.
If you’re into other facts about our Solar system here’s a link to our Solar system playlist. Thanks to Ben Johnson and Tal Ghengis, and the members of the Guide to Space community who keep these shows rolling. Love space science? Want to see episodes before anyone else? Get extras, contests, and shenanigans with Jay, myself and the rest of the team. Get in on the action. Click here.

Posted on by Fraser Cain

Weekly Space Hangout – Oct 2, 2015: Water on Mars, Blood Moon Eclipses, and More Pluto!

Host: Fraser Cain (@fcain)

Guests:

Morgan Rehnberg (cosmicchatter.org / @MorganRehnberg )
Pamela Gay (cosmoquest.org / @cosmoquestx / @starstryder)
Kimberly Cartier (@AstroKimCartier )
Brian Koberlein (@briankoberlein / briankoberlein.com)
Alessondra Springmann (@sondy)
Continue reading “Weekly Space Hangout – Oct 2, 2015: Water on Mars, Blood Moon Eclipses, and More Pluto!”

Posted on by Fraser Cain

Can You Kill a Star With Iron?

Can You Kill a Star With Iron?

Since the energy required to fuse iron is more than the energy that you get from doing it, could you use iron to kill a star like our sun?

A fan favorite was How Much Water Would it Take to Extinguish the Sun? Go ahead and watch it now if you like. Or… if you don’t have time to watch me set up the science, deliver a bunch of hilarious zingers and obscure sci-fi references, here’s the short version:

The Sun is not on fire, it’s a fusion reaction. Hydrogen mashes up to produce helium and energy. Lots and lots of energy. Water is mostly hydrogen, adding water would give more fuel and make it burn hotter. But some of you clever viewers proposed another way to kill the Sun. Kill it with iron!

Iron? That seems pretty specific. Why iron and not something else, like butter, donuts, or sitting on the couch playing video games – all the things working to kill me? Is iron poison to stars? An iron bar? Possibly iron bullets? Iron punches? Possibly from fashioning a suit and attacking it as some kind of Iron Man?

Time for some stellar physics. Stars are massive balls of plasma. Mostly hydrogen and helium, and leftover salad from the Big Bang. Mass holds them together in a sphere, creating temperatures and pressures at their cores, where atoms of hydrogen are crushed together into helium, releasing energy. This energy, in the form of photons pushes outward. As they escape the star, this counteracts the force of gravity trying to pull it inward.

Over the course of billions of years, the star uses up the reserves of hydrogen, building up helium. If it’s massive enough, it will switch to helium when the hydrogen is gone. Then it can switch to oxygen, and then silicon, and all the way up the periodic table of elements.

The most massive stars in the Universe, the ones with at least 8 times the mass of the Sun, have enough temperature and pressure that they can fuse elements all the way up to iron, the 26th element on the Periodic Table. At that point, the energy required to fuse iron is more than the energy that you get from fusing iron, no matter how massive a star you are.

Massive Young Stellar Object HD200775 within the reflection nebula NGC7023.
Massive Young Stellar Object HD200775 within the reflection nebula NGC7023.

In a fraction of a second, the core of the Sun shuts off. It’s no longer pushing outward with its light pressure, and so the outer layers collapse inward, creating a black hole and a supernova. It sure looks like the build up of iron in the core killed it.

Is it true then? Is iron the Achilles heel of stars? Not really. Iron is the byproduct of fusion within the most massive stars. Just like ash is the byproduct of combustion, or poop is the byproduct of human digestion.

It’s not poison, which stops or destroys processes within the human body. A better analogy might be fiber. Your body can’t get any nutritional value out of fiber, like grass. If all you had to eat was grass, you’d starve, but it’s not like the grass is poisoning you. As long as you got adequate nutrition, you could eat an immense amount of grass and not die. It’s about the food, not the grass.

The Sun already has plenty of iron; it’s 0.1% iron. That little nugget would work out to be 330 times the mass of the Earth. If you gave it much more iron, it would just give the Sun more mass, which would give it more gravity to raise the temperature and pressure at the core, which would help it do even more fusion.

This image shows iron debris in Tycho's supernova remnant. Credit: NASA/CXC/Chinese Academy of Sciences/F. Lu et al.
This image shows iron debris in Tycho’s supernova remnant. Credit: NASA/CXC/Chinese Academy of Sciences/F. Lu et al.

If you just poured iron into a star, it wouldn’t kill it. It would just make it more massive and then hotter and capable of supporting the fusion of heavier elements. As long as there’s still viable fuel at the core of the star, and adequate temperatures and pressures, it’ll continue fusing and releasing energy.

If you could swap out the hydrogen in the Sun with a core of iron, you would indeed kill it dead, or any star for that matter. It wouldn’t explode, though. Only if it was at least 8 times the mass of the Sun to begin with. Then would you have enough mass bearing down on the inert core to create a core collapse supernova.

In fact, since you’ve got the power to magically replace stellar cores, you would only need to replace the Sun’s core with carbon or oxygen to kill it. It actually doesn’t have enough mass to fuse even carbon. As soon as you replaced the Sun’s core, it would shut off fusion. It would immediately become a white dwarf, and begin slowly cooling down to the background temperature of the Universe.

Iron in bullet, bar, man or any other form isn’t poison to a star. It just happens to be an element that no star can use to generate energy from fusion. As long as there’s still viable fuel at the core of a star, and the pressure and temperature to bring them together, the star will continue to pump out energy.

What other exotic ways would you use to try and kill the Sun? Give us your suggestions in the comments below.

Posted on by Fraser Cain

Weekly Space Hangout – Sept 25, 2015: Maggie Scholtz, Mars Rover Drill System Engineer

Host: Fraser Cain (@fcain)

Special Guests:
Maggie Scholtz (@martianmagster), who is a Mechanical Engineer working at JPL. She worked on the Curiosity Rover, primarily on the development of the drill and sampling system.

Guests:
Paul Sutter (pmsutter.com / @PaulMattSutter / AskaSpaceman.com)
Morgan Rehnberg (cosmicchatter.org / @MorganRehnberg )
Dave Dickinson (@astroguyz / www.astroguyz.com)

Continue reading “Weekly Space Hangout – Sept 25, 2015: Maggie Scholtz, Mars Rover Drill System Engineer”

Posted on by Fraser Cain

Is the Universe Dying?

Is the Universe Dying?

Is our 13.8 billion year old universe actually in its death throes?

Poor Universe, its demise announced right in it’s prime. At only 13.8 billion years old, when you peer across the multiverse it’s barely middle age. And yet, it sadly dwindles here in hospice.

Is it a Galactus infestation? The Unicronabetes? Time to let go, move on and find a new Universe, because this one is all but dead and gone and but a shell of its former self.

The news of imminent demise was recently broadcast in mid 2015. Based on research looking at the light coming from over 200,000 galaxies, they found that the galaxies are putting out half as much light as they were 2 billion years ago. So if our math is right, less light equals more death.

So tell it to me straight, Doctor Spaceman(SPAH-CHEM-AN), how long have we got? Astronomers have known for a long time that the Universe was much more active in the distant past, when everything was closer and denser, and better. Back then, more of it was the primordial hydrogen left over from the Big Bang, supplying galaxies for star formation. Currently, there are only 1 to 3 new stars formed in the Milky Way every year. Which is pretty slow by Milky Way standards.

Not even at the busiest time of star formation, our Sun formed 5 billion years ago. 5 billion years before that, just a short 4 billion after the Big Bang, star formation peaked out. There were 30 times more stars forming then, than we see today.

When stars were formed actually makes a difference. For example, the fact that it took so long for our Sun to form is a good thing. The heavier elements in the Solar System, really anything higher up the periodic table from hydrogen and helium, had to be formed inside other stars. Main sequence stars like our own Sun spew out heavier elements from their solar winds, while supernovae created the heaviest elements in a moment of catastrophic collapse. Astronomers are pretty sure we needed a few generations of stars to build up enough of the heavier elements that life depends on, and probably wouldn’t be here without it.

Even if life did form here on Earth billions of years ago, when the Universe was really cranking, it would wish it was never born. With 30 times as much star formation going on, there would be intense radiation blasting away from all these newly forming stars and their subsequent supernovae detonations. So be glad life formed when it did. Sometimes a little quiet is better.

So, how long has the Universe got? It appears that it’s not going to crash together in the future, it’s just going to keep on expanding, and expanding, forever and ever.

Our eyes would never see the Crab Nebula as this Hubble image shows it. Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)
Our eyes would never see the Crab Nebula as this Hubble image shows it. Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)

In a few billion years, star formation will be a fraction of what it is today. In a few trillion, only the longest lived, lowest mass red dwarfs will still be pushing out their feeble light. Then, one by one, galaxies will see their last star flicker and fade away into the darkness. Then there’ll only be dead stars and dead planets, cooling down to the background temperature of the Universe as their galaxies accelerate from one another into the expanding void.

Eventually everything will be black holes, or milling about waiting to be trapped in black holes. And these black holes themselves will take an incomprehensible mighty pile of years to evaporate away to nothing.

So yes, our Universe is dying. Just like in a cheery Sartre play, it started dying the moment it began its existence. According to astronomers, the Universe will never truly die. It’ll just reach a distant future when there’s so little usable energy, it’ll be mostly dead. Dead enough? Dead inside.

As Miracle Max knows, mostly dead is still slightly alive. Who knows what future civilizations will figure out in the googol years between then and now.

Too sad? Let’s wildly speculate on futuristic technologies advanced civilizations will use to outlast the heat death of the Universe or flat out cheat death and re-spark it into a whole new cycle of Universal renewal.