What-If 0114: "Antimatter"

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What-If 0114: "Antimatter"

Postby Envelope Generator » Thu Oct 02, 2014 6:50 am UTC

Antimatter

What if everything was antimatter, EXCEPT Earth?

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Re: What-If 0114: "Antimatter"

Postby ThemePark » Thu Oct 02, 2014 7:13 am UTC

What if everything was antimatter, EXCEPT Earth?


Does it really matter?
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Re: What-If 0114: "Antimatter"

Postby rhialto » Thu Oct 02, 2014 7:15 am UTC

So Venus is antimatter!?

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Re: What-If 0114: "Antimatter"

Postby Mikeski » Thu Oct 02, 2014 7:32 am UTC

This steady flow of material (which would be worst around dawn, when your house was facing in the direction of Earth's motion).

I'd like to buy a verb.

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Re: What-If 0114: "Antimatter"

Postby Jiffy » Thu Oct 02, 2014 8:51 am UTC

rhialto wrote:So Venus is antimatter!?

That would make for a great Sci-Fi plot -

A decade ago, nobody knew why Venus was the boiling hell it was. Astronomers built models, physicists ran simulations, engineers devoted entire supercomputers to the research. It seemed impossible - the distance from the sun, the magnetic field, the atmospheric composition... it didn't add up. It was a complete mystery. Until in 2006, Britain's space program decided to land a rover on it.

The explosion rocked the solar system, sending gamma rays and vaporized debris flying through the night sky. Venus was slammed out of its orbit, and came careening towards us. By some mind-blowing coincidence, our gravity fields crossed, locking the two planets into a terrifying embrace. The moon ejected into the sun, Venus replaced our friendly tide-maintaining satellite - but only half as far away from us.

The governments fell into disarray. Frantic measures were taken to stop the propagating space auroras forming in the sky. But after the brief panic, our civilization dawned into a new, beautiful age - the age of antimatter-powered energy.

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Re: What-If 0114: "Antimatter"

Postby black_pignouf » Thu Oct 02, 2014 10:57 am UTC

However, it's easy to use a telescope to rule out one possibility: That everything in the sky is antimatter.

I don't understand the logic behind it.
I read somewhere that anti-photons are just normal photons. Why would the telescope catch fire if everything in the sky is antimatter?

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Re: What-If 0114: "Antimatter"

Postby brenok » Thu Oct 02, 2014 11:14 am UTC

black_pignouf wrote:
However, it's easy to use a telescope to rule out one possibility: That everything in the sky is antimatter.

I don't understand the logic behind it.
I read somewhere that anti-photons are just normal photons. Why would the telescope catch fire if everything in the sky is antimatter?

Did you read the what-if? All of it was based on this scenario.

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Re: What-If 0114: "Antimatter"

Postby black_pignouf » Thu Oct 02, 2014 11:24 am UTC

Did you read the what-if? All of it was based on this scenario.

So, you might as well use a car or an elephant to rule out this possibility.
You don't need a telescope. Am I right?

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Re: What-If 0114: "Antimatter"

Postby brenok » Thu Oct 02, 2014 11:31 am UTC

black_pignouf wrote:
Did you read the what-if? All of it was based on this scenario.

So, you might as well use a car or an elephant to rule out this possibility.
You don't need a telescope. Am I right?

Yes, I believe that's the joke. You'd expect that if one uses a telescope to make an astronomical discovery he'd need to use the lens to see through, and the comic is a subversion of that.

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Re: What-If 0114: "Antimatter"

Postby Flumble » Thu Oct 02, 2014 11:32 am UTC

Jiffy wrote:The governments fell into disarray. Frantic measures were taken to stop the propagating space auroras forming in the sky. But after the brief panic, our civilization dawned into a new, beautiful age - the age of antimatter-powered energy.

...with the new superpowers being the ones that have expertise in rocket science, namely the US, Russia, Japan... and maybe the EU, unless Russian/American/corporate infiltrators keep pushing the esa back.
Of course the big oil companies will do whatever it takes to sabotage any attempt to harvest antimatter if it's not their own.

I guess the scenario also involves global warming, due to the constant annihilation of antimatter and matter debris.


black_pignouf wrote:
Did you read the what-if? All of it was based on this scenario.

So, you might as well use a car or an elephant to rule out this possibility.
You don't need a telescope. Am I right?

Yes. You can even check if you are on fire yourself, but that would be incredibly painful in one of the outcomes.

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Re: What-If 0114: "Antimatter"

Postby cellocgw » Thu Oct 02, 2014 11:37 am UTC

I'm sensing a great disturbance in the force ^H^H^H^Hforums, as though a million OTTers noticed the first drawing's blatant reference to the OTT, and screamed in dismay at the lack of any title-text.

Why no Markdown for strike-thru text?
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Re: What-If 0114: "Antimatter"

Postby Flumble » Thu Oct 02, 2014 12:46 pm UTC

cellocgw wrote:the lack of any title-text.

Though not an OTTer, I, too, was, even more because the other images had title-texts, put off by the lack of a title-text.

cellocgw wrote:Why no Markdown for strike-thru text?

Markdown? We do have the strikethrough tag on the forums. (according to the internet ~~ does strikethrough in markdown)

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Re: What-If 0114: "Antimatter"

Postby Sizik » Thu Oct 02, 2014 12:54 pm UTC

This steady flow of material.


I think Randall accidentally a sentence.
she/they
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Re: What-If 0114: "Antimatter"

Postby Sizik » Thu Oct 02, 2014 1:04 pm UTC

This steady flow of material.


I think Randall accidentally a sentence.
she/they
gmalivuk wrote:
King Author wrote:If space (rather, distance) is an illusion, it'd be possible for one meta-me to experience both body's sensory inputs.
Yes. And if wishes were horses, wishing wells would fill up very quickly with drowned horses.

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Re: What-If 0114: "Antimatter"

Postby Schumi » Thu Oct 02, 2014 1:41 pm UTC

My first thought was that the moon landings would have been much more spectacular.

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Re: What-If 0114: "Antimatter"

Postby cellocgw » Thu Oct 02, 2014 1:47 pm UTC

Sizik wrote:
This steady flow of material.


I think Randall accidentally a sentence.

Sizik wrote:
This steady flow of material.


I think Randall accidentally a sentence.


I think you accidentally accidentally a post. :mrgreen: :oops:
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Re: What-If 0114: "Antimatter"

Postby Whizbang » Thu Oct 02, 2014 1:47 pm UTC

Some words in this article may have been hit by anti-words.

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Re: What-If 0114: "Antimatter"

Postby Barstro » Thu Oct 02, 2014 1:50 pm UTC

As you will be able to tell, I am not a physicist.

I always thought matter and antimatter were in the same quantities, but settled in different areas of the universe because, on the large scale, they repelled each other. Small bits of matter can collide with antimatter to create explosions, but any groupings of sufficient size of matter or antimatter would repel the other; much how it takes a certain amount of magnetic force to cause objects to resist the force of gravity.

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Re: What-If 0114: "Antimatter"

Postby stoppedcaring » Thu Oct 02, 2014 2:19 pm UTC

Barstro wrote:As you will be able to tell, I am not a physicist.

I always thought matter and antimatter were in the same quantities, but settled in different areas of the universe because, on the large scale, they repelled each other. Small bits of matter can collide with antimatter to create explosions, but any groupings of sufficient size of matter or antimatter would repel the other; much how it takes a certain amount of magnetic force to cause objects to resist the force of gravity.

This would be cool (for some values of cool), but no. Antimatter has the opposite electromagnetic charges, but the same gravitational parameters. So anti-electrons (called positrons) are positively-charged and would be electromagnetically attracted to ordinary electrons, but are still affected by gravity in the same way as electrons.

Gravity is a function of the relationship between mass-energy and spacetime; the charge (or non-charge, in the case of neutrons/neutrinos) has no affect on it. Gravity doesn't care whether something is a proton or a neutron or an antiproton (well, technically a neutron is just slightly heavier than the other two, but that's beside the point).

Jiffy wrote:
rhialto wrote:So Venus is antimatter!?

That would make for a great Sci-Fi plot -

A decade ago, nobody knew why Venus was the boiling hell it was. Astronomers built models, physicists ran simulations, engineers devoted entire supercomputers to the research. It seemed impossible - the distance from the sun, the magnetic field, the atmospheric composition... it didn't add up. It was a complete mystery. Until in 2006, Britain's space program decided to land a rover on it.

The explosion rocked the solar system, sending gamma rays and vaporized debris flying through the night sky. Venus was slammed out of its orbit, and came careening towards us.

It would have to be one hell of a rover. As Randall points out, an antimatter version of Chelyabinsk meteor would have released the equivalent energy of the Chicxulub asteroid that started the extinction of the dinosaurs...but Chicxulub certainly didn't slam Earth out of its orbit. The Chelyabinsk meteor was around 13,000 tonnes, more than six times the entire Space Shuttle launch mass. A 2006-era launch vehicle capable of carrying a Chelyabinsk-sized payload would be almost 110 times larger than the Space Shuttle...that's four Titanics stacked end-to-end.

And even that wouldn't budge an antimatter Venus.

Theia, the planetary body whose collision with Earth formed our Moon, likely had a mass similar to Mars and an initial impact velocity of less than 4 km/s, giving the impact a total kinetic energy of roughly 4e34 J. Now, the momentum exchange is the more important point for altering anti-Venus's orbit, but since antimatter's advantage is energy, we'll go with that. In order to release 4e34 J of energy, you'd need to have at least 2.2e14 tonnes of matter hitting anti-Venus. So the rover would need to weigh about as much as Saturn's shepherd moon Prometheus.

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Re: What-If 0114: "Antimatter"

Postby airdrik » Thu Oct 02, 2014 2:41 pm UTC

Wait, he failed to answer one more incredibly important related question:
What if everything was antimatter?

Just think, all of this antimatter interacting with ... more antimatter (cue deflated excitement). Hmm.. I guess that isn't very interesting as it would look exactly as it does already (except if going by a strict definition of "everything", there would be no non-anti matter for the antimatter to interact with, and we would just assign the term "matter" to that which everything is made of and there would be no antimatter).

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Re: What-If 0114: "Antimatter"

Postby Introbulus » Thu Oct 02, 2014 2:45 pm UTC

I like these What-Ifs with remarkably clandestine doomsday scenarios.

They make me feel slightly more secure, in a universe where everything is constantly on the verge of complete and utter destruction and our society is run by screaming insane monkeys. (But enough about *insert elected official/dictator here*...)
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Re: What-If 0114: "Antimatter"

Postby Moose Anus » Thu Oct 02, 2014 3:59 pm UTC

airdrik wrote:Wait, he failed to answer one more incredibly important related question:
What if everything was antimatter?

Just think, all of this antimatter interacting with ... more antimatter (cue deflated excitement). Hmm.. I guess that isn't very interesting as it would look exactly as it does already (except if going by a strict definition of "everything", there would be no non-anti matter for the antimatter to interact with, and we would just assign the term "matter" to that which everything is made of and there would be no antimatter).
Yeah, matter is just what we call normal stuff. Antimatter is what we called the other stuff after we figured out it probably exists. If the substances were reversed, we would have called antimatter "matter" at first, and called matter "antimatter" when we found out about it.

Also, if electrons were originally assigned a positive charge (rather than negative), then positrons would instead be called "negatrons," which sounds awesome.
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Re: What-If 0114: "Antimatter"

Postby stoppedcaring » Thu Oct 02, 2014 4:21 pm UTC

Moose Anus wrote:If electrons were originally assigned a positive charge (rather than negative), then positrons would instead be called "negatrons," which sounds awesome.

But "negatronic brain" just doesn't have that ring to it.

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Re: What-If 0114: "Antimatter"

Postby Flumble » Thu Oct 02, 2014 4:30 pm UTC

stoppedcaring wrote:
Moose Anus wrote:If electrons were originally assigned a positive charge (rather than negative), then positrons would instead be called "negatrons," which sounds awesome.

But "negatronic brain" just doesn't have that ring to it.

Chances are it would've been called a "photonic brain" or "bosonic brain". Bosonic brain even has the alliteration to make it sound more bad-ass.

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Re: What-If 0114: "Antimatter"

Postby stoppedcaring » Thu Oct 02, 2014 4:34 pm UTC

Flumble wrote:
stoppedcaring wrote:
Moose Anus wrote:If electrons were originally assigned a positive charge (rather than negative), then positrons would instead be called "negatrons," which sounds awesome.

But "negatronic brain" just doesn't have that ring to it.

Chances are it would've been called a "photonic brain" or "bosonic brain". Bosonic brain even has the alliteration to make it sound more bad-ass.

"Your kung fu is no match for my fermionic brain!"

"Quantum brain!"

"Wavefunction brain!"

"Mass-energy braaaaiiiinnn!"

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Re: What-If 0114: "Antimatter"

Postby Moose Anus » Thu Oct 02, 2014 4:37 pm UTC

Flumble wrote:
stoppedcaring wrote:
Moose Anus wrote:If electrons were originally assigned a positive charge (rather than negative), then positrons would instead be called "negatrons," which sounds awesome.

But "negatronic brain" just doesn't have that ring to it.

Chances are it would've been called a "photonic brain" or "bosonic brain". Bosonic brain even has the alliteration to make it sound more bad-ass.
Bosonic brain makes me think of Bozo the Clown.
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Re: What-If 0114: "Antimatter"

Postby Jackpot777 » Thu Oct 02, 2014 5:52 pm UTC

Jiffy wrote:
rhialto wrote:So Venus is antimatter!?

That would make for a great Sci-Fi plot -

A decade ago, nobody knew why Venus was the boiling hell it was. Astronomers built models, physicists ran simulations, engineers devoted entire supercomputers to the research. It seemed impossible - the distance from the sun, the magnetic field, the atmospheric composition... it didn't add up. It was a complete mystery. Until in 2006, Britain's space program decided to land a rover on it.

The explosion rocked the solar system, sending gamma rays and vaporized debris flying through the night sky. Venus was slammed out of its orbit, and came careening towards us. By some mind-blowing coincidence, our gravity fields crossed, locking the two planets into a terrifying embrace. The moon ejected into the sun, Venus replaced our friendly tide-maintaining satellite - but only half as far away from us.

The governments fell into disarray. Frantic measures were taken to stop the propagating space auroras forming in the sky. But after the brief panic, our civilization dawned into a new, beautiful age - the age of antimatter-powered energy.


Venera 9. And it wasn't the only one.

Image

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Re: What-If 0114: "Antimatter"

Postby Iamthep » Thu Oct 02, 2014 8:16 pm UTC

I wonder if this what-if is correct. If you took a ball of anti matter and a ball of matter and tried to join them they would essentially just bounce off of each other. It would be very very hard to get them to completely join.

If a matter asteroid hits the earth and delivers all of its kinetic energy to the earth then an anti-matter asteroid would probably just annihilate enough matter to delver 2x the energy that an equivalent matter asteroid would deliver. The rest of the asteroid would simply reverse direction and head on out.

Of course that assumes that all of the resultant matter-anti-matter reactions delivered energy directly opposing the direction of travel of the asteroid.

So how much energy, dispersed in completely random directions would have to be released to stop the asteroid and send it hurtling back away from earth? Or would any release in energy immediately shatter the asteroid into tiny fragments? Or perhaps the asteroid would be caught by the earth and then sputter around in the atmosphere gradually dwindling in size, just like drops of water on a very hot metal surface does.

I feel that this deserves more thought put into it!

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Re: What-If 0114: "Antimatter"

Postby stoppedcaring » Thu Oct 02, 2014 8:41 pm UTC

Iamthep wrote:I wonder if this what-if is correct. If you took a ball of anti matter and a ball of matter and tried to join them they would essentially just bounce off of each other. It would be very very hard to get them to completely join.

If a matter asteroid hits the earth and delivers all of its kinetic energy to the earth then an anti-matter asteroid would probably just annihilate enough matter to delver 2x the energy that an equivalent matter asteroid would deliver. The rest of the asteroid would simply reverse direction and head on out.

Of course that assumes that all of the resultant matter-anti-matter reactions delivered energy directly opposing the direction of travel of the asteroid.

Well, he does address this, in superscript pop-up note #10:

"If an antimatter meteor is large enough, encountering a cloud could launch some of it backward without completely destroying it. However, it's hard to come up with a practical scenario in which a meteor would exhibit this effect in Earth's atmosphere--unless it were so large that it would have basically destroyed the planet anyway."

That link is to a book with one of the coolest possible titles: Cosmological Pattern of Microphysics in the Inflationary Universe. But anyway, an antimatter object would basically just be swallowed up by the Earth's atmosphere, causing it to be surrounded by annihilation reactions and thus be completely consumed. In the absence of atmosphere, two objects of similar mass could indeed "bounce" apart due to the initial energy burst, but that's not what we're dealing with here. The objects need to be similar in mass because the rate of annihilation depends on surface area; an object with a small surface area will won't have a high enough rate of annihilation along its facing side to counteract the larger object's gravity.

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Re: What-If 0114: "Antimatter"

Postby Lazy Tommy » Fri Oct 03, 2014 10:18 am UTC

But the big asteroids would get us first. Even a relatively small object like the Chelyabinsk meteor would deliver as much energy as the meteor that killed the dinosaurs.


Now I want to know what an antimatter asteroid the size of the Chicxulub impactor would do. I guess it's pretty much a given that it would eradicate all life on Earth, but would the planet stay in one piece? Would it melt and eventually re-solidify to its current condition, or would the pieces be blown apart with enough force to leave their current orbit?

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Re: What-If 0114: "Antimatter"

Postby stoppedcaring » Fri Oct 03, 2014 2:14 pm UTC

Lazy Tommy wrote:
But the big asteroids would get us first. Even a relatively small object like the Chelyabinsk meteor would deliver as much energy as the meteor that killed the dinosaurs.


Now I want to know what an antimatter asteroid the size of the Chicxulub impactor would do. I guess it's pretty much a given that it would eradicate all life on Earth, but would the planet stay in one piece? Would it melt and eventually re-solidify to its current condition, or would the pieces be blown apart with enough force to leave their current orbit?

Chicxulub was likely 10 km in diameter. As I explain above, an antimatter impactor would need to be roughly the size of Prometheus in order to release the equivalent energy of the Theia collision which formed our moon. The mean radius of Prometheus is an order of magnitude greater than that of the Chicxulub impactor, meaning its mass is a thousand times greater. So a thousand antimatter Chicxulubs could conceivably be enough to create another moon, but wouldn't be sufficient to break Earth apart completely.

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Re: What-If 0114: "Antimatter"

Postby schapel » Fri Oct 03, 2014 6:29 pm UTC

stoppedcaring wrote: So a thousand antimatter Chicxulubs could conceivably be enough to create another moon, but wouldn't be sufficient to break Earth apart completely.

What if they were traveling at 99.999999% the speed of light?

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Re: What-If 0114: "Antimatter"

Postby stoppedcaring » Fri Oct 03, 2014 6:52 pm UTC

schapel wrote:
stoppedcaring wrote: So a thousand antimatter Chicxulubs could conceivably be enough to create another moon, but wouldn't be sufficient to break Earth apart completely.

What if they were traveling at 99.999999% the speed of light?

Then their relativistic kinetic energy would be 3,536 times greater than the total energy produced by annihilation reactions, meaning the impact would be 1.4e38 J, only 0.03% of which was nuclear. So basically it might as well be regular rock.

Strictly speaking, the 4e34 J of the Theia impact was greater than the gravitational binding energy of the Earth, but since it was distributed unevenly it was sufficient only to knock a moon into space. Multiplying that by 3,500 would definitely be enough to turn the Earth into an asteroid belt.

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Re: What-If 0114: "Antimatter"

Postby schapel » Fri Oct 03, 2014 8:50 pm UTC

stoppedcaring wrote:
schapel wrote:What if they were traveling at 99.999999% the speed of light?

Then their relativistic kinetic energy would be 3,536 times greater than the total energy produced by annihilation reactions, meaning the impact would be 1.4e38 J, only 0.03% of which was nuclear. So basically it might as well be regular rock.

Even as I asked the question, I knew the answer would be... well, then, they might as well be made of ordinary matter. Actually, I put in only five 9s at first, then added three more just to be sure.

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Re: What-If 0114: "Antimatter"

Postby Pfhorrest » Fri Oct 03, 2014 8:57 pm UTC

stoppedcaring wrote:Strictly speaking, the 4e34 J of the Theia impact was greater than the gravitational binding energy of the Earth, but since it was distributed unevenly it was sufficient only to knock a moon into space. Multiplying that by 3,500 would definitely be enough to turn the Earth into an asteroid belt.

Where did the rest of the energy go then? Lost to heat? Changed the orbit of the Earth? Is part of the Earth-Moon system composed of the mass of Theia itself, or did most or at least some of that (and maybe some of the old Earth?) end up flung out into space after the impact?
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Re: What-If 0114: "Antimatter"

Postby stoppedcaring » Fri Oct 03, 2014 9:54 pm UTC

Pfhorrest wrote:
stoppedcaring wrote:Strictly speaking, the 4e34 J of the Theia impact was greater than the gravitational binding energy of the Earth, but since it was distributed unevenly it was sufficient only to knock a moon into space. Multiplying that by 3,500 would definitely be enough to turn the Earth into an asteroid belt.

Where did the rest of the energy go then? Lost to heat? Changed the orbit of the Earth? Is part of the Earth-Moon system composed of the mass of Theia itself, or did most or at least some of that (and maybe some of the old Earth?) end up flung out into space after the impact?

An open question in astrogeohistory. My understanding of the consensus is that the moon is composed mostly of crustal material from Theia and Earth, while the cores of both Theia and Earth survived and ended up joining. Computer models indicate that Theia couldn't have been moving much faster than 4 km/s relative to Earth.

The excess energy would have been distributed through the random kinetic energy of the rings that formed around Earth; within a few centuries these rings would have coalesced into the moon, which would eventually radiated away that energy. It is likely that a second proto-moon formed at the Moon's L2 point but ended up colliding with the Moon after enough it had receded a bit further from the Earth.

schapel wrote:
stoppedcaring wrote:
schapel wrote:What if they were traveling at 99.999999% the speed of light?

Then their relativistic kinetic energy would be 3,536 times greater than the total energy produced by annihilation reactions, meaning the impact would be 1.4e38 J, only 0.03% of which was nuclear. So basically it might as well be regular rock.

Even as I asked the question, I knew the answer would be... well, then, they might as well be made of ordinary matter. Actually, I put in only five 9s at first, then added three more just to be sure.

I wondered why you were between two of the steps in what-if #20.

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Re: What-If 0114: "Antimatter"

Postby dtilque » Sat Oct 04, 2014 8:56 am UTC

Schumi wrote:My first thought was that the moon landings would have been much more spectacular.


Luna 2, way back in 1959, would have given us a clue that manned moonshots were a bad idea, when it became an impact mission visible from Earth....


airdrik wrote:Wait, he failed to answer one more incredibly important related question:
What if everything was antimatter?

Just think, all of this antimatter interacting with ... more antimatter (cue deflated excitement). Hmm.. I guess that isn't very interesting as it would look exactly as it does already (except if going by a strict definition of "everything", there would be no non-anti matter for the antimatter to interact with, and we would just assign the term "matter" to that which everything is made of and there would be no antimatter).


We'd know everything was anti-mattter if positrons orbited backwards and we had to use the left-hand rule. Also, the Earth would be cubical and Spock would have a goatee.


I wonder what effects there'd be if the entire solar system were normal matter but the rest of the universe was antimatter. Would there be any effect except for cosmic rays (which Randall ignored/forgot about in this what-if) and the heliopause being more energenic?
“This world is a strange madhouse. Currently, every coachman and every waiter is debating whether relativity theory is correct. Belief in this matter depends on political party affiliation.”
-- Albert Einstein, 12 September 1920

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Flumble
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Re: What-If 0114: "Antimatter"

Postby Flumble » Sat Oct 04, 2014 11:38 am UTC

stoppedcaring wrote:An open question in astrogeohistory. My understanding of the consensus is that the moon is composed mostly of crustal material from Theia and Earth, while the cores of both Theia and Earth survived and ended up joining. Computer models indicate that Theia couldn't have been moving much faster than 4 km/s relative to Earth.

The excess energy would have been distributed through the random kinetic energy of the rings that formed around Earth; within a few centuries these rings would have coalesced into the moon, which would eventually radiated away that energy. It is likely that a second proto-moon formed at the Moon's L2 point but ended up colliding with the Moon after enough it had receded a bit further from the Earth.

Only 4km/s? That's a boring speed. If you were to witness it, well, you should just record the whole event and play it at 10x or 50x to see a nice epic explosion.
On the other hand a few centuries sounds like a very quick formation. (alright, that's thousands of laps around the Earth, so it's fair to assume that the largest chunk has swept up most of the debris)

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Re: What-If 0114: "Antimatter"

Postby KarenRei » Sun Oct 05, 2014 5:25 pm UTC

Has anyone else here double checked Randal's math?

The sun imparts 1e17 joules to Earth every day.
1 gram of antimatter annihilating with 1 gram of matter yields 1,8e14 joules. Say half of that escapes directly to space, so 9e13 joules per gram.
Scale to 100 tonnes of antimatter dust and debris per day, that's 9e21 joules.

90.000 times greater. The equivalent of 143 billion Hiroshima bombs per day (that's like one going off every 1,9 kilometers). The animatter is not just a "most likely be enough to tip the Earth into a "runaway greenhouse" scenario". It's a "instantly obliterate all life on earth" scenario.

Update: See below, I mixed up days and seconds. Whoops! Still, works out to as much gamma hitting earth as sunlight - still sounds like a near-instant-death scenario.
Last edited by KarenRei on Tue Oct 07, 2014 1:00 pm UTC, edited 4 times in total.

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Re: What-If 0114: "Antimatter"

Postby Lazy Tommy » Tue Oct 07, 2014 10:32 am UTC

KarenRei wrote:Has anyone else here double checked Randal's math?

The sun imparts 1e16 joules to Earth every day.
1 gram of antimatter annihilating with 1 gram of matter yields 1,8e14 joules. Say half of that escapes directly to space, so 9e13 joules per gram.
Scale to 100 tonnes of antimatter dust and debris per day, that's 9e21 joules.

900.000 times greater. The equivalent of 143 billion Hiroshima bombs per day (that's like one going off every 1,9 kilometers). The animatter is not just a "most likely be enough to tip the Earth into a "runaway greenhouse" scenario". It's a "instantly obliterate all life on earth" scenario.

Where did you get that figure for the power of sunlight? Wikipedia says the solar energy flux at 1 AU is 1.4e3 W/m^2, and that would be 1.8e17 W for the whole planet, or 1.5e22 J/day. Multiply by 0.7 to take the Earth's albedo into account, and you get an overall absorption of about 1e22 J/day. (I'm guessing your figure is one million times lower because of a missing km^2 → m^2 conversion.)

That means that 9e21 J/day from the ongoing matter/antimatter annihilation would still almost double the amount of energy received by the Earth. I don't know what the tipping point for the "runaway greenhouse" scenario would be, but regardless, this seems like a very unpleasant scenario for most higher forms of life.

(Things I learned today: the energy the Earth receives from the sun is equivalent to 160 billion Hiroshima explosions per day. That does sound insane. Good thing it is delivered mainly as visible light!)

UPDATE: While the Wikipedia page for the Hiroshima bomb says that it had a yield of 67 GJ, that seems to be a mistake. They appear to assume that 1 kiloton TNT equals about 4 GJ, while the actual ratio is 1 kT ≈ 4 TJ. So, total terrestrial insolation is 160 million Little Boys per day, not 160 billion. Whew.
Last edited by Lazy Tommy on Tue Oct 07, 2014 1:10 pm UTC, edited 1 time in total.


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