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I don't think they mean that it would induce a self-sustaining fusion reaction, but the simple act of the atoms in the balls smashing into the atoms in the air being energetic enough to make them fuse.

Each time he says 'fusion' he literally means 'atomic nuclei getting close enough together that the strong nuclear interaction overwhelms the electromagnetic interaction'. For example, when you mention sputtering -- yes, the ball is sputtering, but, those pieces are moving so fast even still that when they hit air molecules, the total energy (and thus effective temperature) is sufficient for the sputtered pieces to undergo atomic fusion with the air molecules that strike the sputtered pieces.

I love how both you and Randall looked at this scenario, realized how destructive it would be, and said, "Yeah, that's hit by pitch, so the batter gets to walk."

The fusion confinement mechanism of 0.9C baseball vs air would be, inertial. There is no time for the atomic nuclei to physically move out of the way due to their own inertia

Yes - it is fusion! Fusion happens when atomic nuclei collide with sufficient energy to overcome electrostatic repulsion... in the sun, in a tokamak reactor and on the ball. A proton at 0.9c carries about 1 Gev energy. 1 Mev is more than enough to fuse hydrogen... no confinement required... just kinetic energy.

Confinement isn't necessary for fusion if the energy and density is high enough for it to happen instantly. A large object traveling at 0.9C through standard atmosphere likely has relative temperatures and pressures higher than any typical fusion reactor.

"As for the rules of baseball this isn't a recommended strategy" ahh i see. good to know

You don't need confinement for fusion, you need confinement for SELF-SUSTAINED fusion, which he did not claim would occur. If two atoms hit each other and become one bigger nucleus atom then there was fusion. Just two atoms.

I believe the fusion referenced is of the same type that is used to produce heavy elements in the element hunt, ie "throw atoms at each other very hard and some will combine."

To take this scenario to a different extreme, the 'Oh My God Particle' was a single proton that was tracked entering Earth's atmosphere at 99.99999999999999999999951% of the speed of light. It coincidentally had the same approximate kinetic energy as a pitched baseball. en.m.wikipedia.org/wiki/Oh-My-God_particle

It will cause fusion, not necessarily sustainable fusion, but rather, beam-target fusion.

I thoroughly enjoyed this video, and yes I was giggling gleefully at some points. Quality content as always. I have the same objection as everyone else about your 'fusion' quibble, but as a linguist I'm going to frame that disagreement a bit differently. I think Randall Munroe (xkcd dude) is consistently referring to nuclear fusion, ie. an atomic nucleus colliding with something to form a different atomic nucleus, but I do agree that the confusion is around definitions of fusion. Between Randall, yourself (Tyler) and some of the comments, I'm seeing 3 different definitions of "fusion": 1. The basic ballistic-event definition: nucleus collides with something else, probably another nucleus, and the two particles fuse to form a different nucleus. 2. The basic system definition: #1 happening in a sustained manner at a macro scale, which I assume is the relevant definition for a nuclear reactor "achieving fusion". 3. The exciting definition: #2 but exothermic, producing more energy than it consumes. -- I think Randall is using definition #1 and you are using definition #2. Both legitimate definitions, and both completely reasonable defaults given your different backgrounds (first-principles dude vs nuclear power industry professional). If we consider the atmosphere as a large stationary target and the ball as a huge number of relativistic particles hitting that target, then we have an absurd number of high-energy particle collisions happening. My understanding is that some fraction of those collisions are going to result in nuclear fusion events, just like the individual fusion events that we use to synthesise heavier elements in a particle accelerator. Hence nuclear fusion in sense #1 but not in sense #2. Have I got the physics right? -- (note for linguists: yes I know I'm using 'definition' where what I really mean is 'sense')

Could the "fusion" he's talking about here be more like the fusion that happens in supernova once it's already started (creating heavier elements due to smashing nuclei, neutrons, etc. together in extreme conditions, but not necessarily self sustaining or even energy positive) than the fusion that powers a normal star or thermonuclear device?

Before you suggest or say you don’t think so on this guys videos, double check, he does the research on these with other professionals.

5:10 as I understand what he means here is that the individual impact events of air molecules hitting the ball have enough energy for some fusion to occur, it's not relying on sustained anything but an instantaneous event. Probably doesn't actually work with the specific molecules but I don't know enough about fusion to say more?

At that speed, the atoms that make up the baseball are allisioning with similar energy and velocity to r-process nucleosynthesis, which I think is what he's calling "fusion".

This is a really good thought experiment for learning to separate terms from common fields that use them and showing them to have other places they exist. Another example might be...something simple like baking. The first thought may be baking food, but you can also bake metals, glass, porciline, And other inedible materials.

it's fusion, but for a very small amount of time

how do you not understand what he means by fusion

Having read the original article several times, and watched the video, it was definitely interesting with your comments basically predicting the rest of the video. Also, as other have stated, I believe you would get nuclear fusion in this scenario, with the individual atoms fusing (and releasing energy). It wouldn't be self-sustaining of course, but, still fusion, isn't it?

You seem to have got the wrong end of the stick about what xkcd is saying about fusion. What he's NOT saying is that you'd ignite a fusion chain reaction in the air. What he IS saying is that some of the atomic nuclei in the ball will fuse with at least some of the nuclei in the molecules of nitrogen and oxygen with which the ball is colliding at 0.9c. And that seems perfectly reasonable.

Looking at the rest of the hit by a pitch rules, he did try to hit the ball, the ball was in the strike zone and probably hitting the batter outside of the strike zone, and the batter would not be able to make an attempt to avoid being touched by the ball. MLB glossary for HBP makes it more clear that a) A stike supersedes hit by a pitch, b) he tried to swing at it, c) he did not attempt to move out of the way. Seems more like a strike/foul ball than a hit by pitch. Now, if the ball hit the bat and parts of the ball made it out of the park, is it a home run? I would say most of the ball ended up behind home plate, which is foul territory, and most likely rule it as a foul ball.

*winds up* I am become destroyer of tan lines.*births another sun using a ball*

The original write up for this was the first ever What If article so it was very much establishing exactly how seriously he was taking everything

I can’t believe you accurately predicted the ending punchline.

8:47 I love how the first thing he completely agrees on is how the incident is going to be ruled. Damn, 4 megatons. That’s a hell of a pitch.

I don't think it will be noticeably oblong. All of that directionality will equalize by the time the fireball developes.

At 90% light speed, in atmosphere? It would probably explode quite violently

Great video as always 🎉

I’m thinking the words heard with the pitch, “You may fire when ready…commence primary ignition…”

I gotta tell you, given this one was the version thing posted on the original text version of What If?, this particular one is one of my favorites, and you making a joke about hit by pitch halfway through had me laughing my ass off. Aside from the disagreement on nuclear fusion, which some other commenters have already addressed, you really were just on the same exact page as Randall Munroe throughout this, and I love it.

I can't stop laughing at the fact that you showed a nuke blast at Bethesda

If a half pound ball is moving at. 9 the speed of light it's gonna fuse with any particles it runs into, in the 90 feet it has to go it will fuse with everything it touches it's a Simple equation

Rundall did not consider relativistic effects. How much geometry will be distorted? Circle or blast turned into ellipsis? At v = 0.9 c this should be pronounced.

forgot the name of the company... they shoot aluminum pellets at 30km per second... hit's hard I bet

What if the ball was spinning 90% speed of light? XD

I remember several years ago I read XKCD book and this was one of my favorites.

When he mentioned that according to the rules this would be a walk, first thought was "well, at least if they decide to continue the game elsewhere with newly assembled teams they could have his replacement walk," but then it would be unlikely anyone would know what happened. Assume it was broadcast live. Ignoring any deliberate delays, latencies alone would keep anyone from seeing the event. The light of the pitch would reach the sensors, but before the signal was processed and transmitted to the next bit of equipment the camera would be gone. I guess if the wizard that caused the ball to go at .9c was located on a distant hill with a camera with a powerful enough zoom to capture the event then maybe we'd know, but I kind of doubt such a wizard is going to be that helpful especially since he's going to be wanted for likely the largest act of terrorism in history.

According to Omni Man, this is how fellow Viltrumites play baseball back home.

Reminds me of in Dragonball Super when two of the literal gods of destruction had a baseball game and their essentially galaxy destroying at that time.

as Randall Munroe has stated either in one of his talks or the intro of one of his books, these what-if questions are to be approached from a mindset of "assume we set the world up in this way. we don't care how it got there, we are just setting it up and hitting play"

The video simply said "fusion" not "sustained fusion" 😭

It is fusion, it is basically beam target fusion, with the ball being the beam and the in comparison basically stationary air being the target.

Crazy about the fusion part not being correct, learned something new thanks to Tyler.

XKCD. Reimagining the apocalypse, one video at a time.

Didn’t know I could even see a video this early.

I hope that they will make the Periodic Table Cubes one into a video. I really would look forward to the reaction.

XKCD is just amazing

Sweet video

The atoms do fuse, but they don't stay. The energy of the collision is miles beyond necessary to completely merge an atomic nucleus before it even has the chance to break. After this collision the atom doesn't just split, it dissolves into atomic particles which are traveling no more than 1.1x the ball's velocity. A subatomic fireball locally mirroring the conditions within an imploding star, but lacking sufficient mass to hold it together.

My understanding is that elements before iron tend to experience fusion in nuclear reactions. Simply because it produces energy. Fusion in reactors or bombs is just too specific. Still quite a lot of different reactions are happening in stars.

Nice of you to talk about my man R.A. Dickey 3 min in

Everyone’s worried about the batter, but imagine being the catcher.

You should watch the video “the scale of mushroom clouds”, it’s an interesting watch!

The ball is at it's own doom

4:46 Really? I thought that it would at least be plausible to get a very small fusion reaction going. You've got matter moving very quickly into what is effectively motionless gas. Now, I know the pressure to create and sustain fusion is immense but I'd imagine a ball moving at .9c could possibly do it. Granted, it would be a very, VERY short amount of time. 7:20 Ah. Never mind.

0:30 Would the baseball deliver all of it's kinetic energy to the bat though? It seems like the ball would only deliver enough energy to the bat to shatter it, then continue on haveing slowed doen by only a few MPH. The atmospheric shock waves might be an issue though.

Ok, so about the nuclear fusion issue - my intuition suggests that the kinetic energy of an atom in the baseball is equivalent to a temerature that is many orders of magnitude more than enough to overcome the Compton barrier for say two nuclei of oxygen or nitrogen, which would be a typical encounter. And if i am not mistaken the boost due to relativistic effects doesn't even make much difference (a mere factor of 27 or so). Of course fusion might not be possible but if so more beause the energies are too high.

So, similar to the Redwing Navajo hydrogen bomb test?

I was under the impression that if it travelled at the speed of the light his energy would be that of half of anti matter, so why wouldn't it fusion? Not enough temperature/energy? The sun has fusion at lower temperature due to gravity, in earth we have it through high temperature (high speed collisions) c isn't speed enough? I am quite puzzled on why it wouldn't fusion

10:22 Hey look! Bethesda!

I confess I have mixed feelings about seeing my home Wheaton, MD, on a map showing the radii of the results of a large thermonuclear explosion in downtown D.C.

Hey Tyler is there a way that I can get in contact with you personally? I’m looking to get into the nuclear industry but I have no idea what to do

Sounds like you'd be moving a hell of a lot further than first base, and first base will be moving with you. Nice to see Bethesda included in the blast area - inspo for a Fallout spin-off?

What do you need a confinement zone for? You have atoms smack into each other at almost light speed. If that doesn't get you fusion, nothing will. Now, _how much_ fusion I can't even begin to guess, and it likely won't matter anyway, the ball itself has a lot more kinetic energy than you get from whatever fusion you will get. Ok, maybe it's _too much_ for fusion, and you only get fission (as in, reduction of atoms to neutrons, protons, perhaps alpha particles, maybe more particles produced by pair production), that's possible. Ionizations? At the outer edges (well, the circumference), perhaps. In front, there's no _time_ for ionization. You'll probably get a lot of random elementary particles and even alpha radiation going in random directions, though. Don't think meteor. Meteors have a few, maybe a few dozen km/s, this is a few hundred thousand km/s. Think CERN.

If the pitcher could use quantum tunneling to get the ball into the catcher's glove without the ball moving through the space between, you it be a ball or a strike?

The end result is always a called game due to: 1. The field being unfit for play 2. Neither team having players left to substitute

3:20 funny you mention Dragon Ball considering they did EXACTLY THAT in a special baseball episode a few years ago, In fact, the ball was probably much faster than light considering that it's Dragon Ball

I think the relatively enormous mass of the ball moving at relativistic speeds ought to do some special kind of damage and I doubt "just adjusting the blast shape" should cut it. The atoms from the ball even after the primary disintegration would still in bulk have a lot of mass and going fast and what that bunch hits is interesting. Not sure how much building matter it should hit before slowing down back to ambient temperature speeds. 🤔🤔

you don’t need confinement if air molecules are slamming into your object at 90% C and essentially becoming a part of the object. Also there js no way any atom of air escapes that region faster than a ball pushing in at 90% C so actually you end up with „technically a confinement”

An oxygen atom that hits a hydrogen atom in the baseball at 0.9c can absolutely fuse. Its not a sustained reaction but other doesnt have to be. To cause fusion all you need is the right atoms colliding at the right speed. Once you have that its just a question of how often that occurs. In this case its less about frequency and more about the number of atoms the ball hits.

For a second I thought you had a flying start, just like the baseball, but it was just a 2020-esque funny-scene-as-intro intro. I waited patiently for you to review this one, was pretty confident you'd get to it before I grew old and gray ^_^.

This is not a practical weapon. It is last resort suicide.

Would it have at that speed particle accelerator like affects and literally break apart the nucleus and produce a burst of quarks like collisions in the LHC. Or would it need to be a lot closer to light speed for that to start happening. Like what would it be like if the ball was traveling at the speed of the omg particle.

Saved the nuke map to bookmarks asap (ok not that fast i did watch the video first, so it wasnt asap, but the next step after that)

Please keep watc'hing more subject zero please!

What if it was raining? Dust particles? Hits a bug?

They don't make em like Nolen Ryan anymore.

I would think 0.9c would be enough to overcome any Coulomb barrier, and the cross section area ... well baseball diameter versus where air molecule could go in a few nanoseconds would be the physics equivalent to "broadside of a barn" hell it would probably also be the entire planet the barn is on. So yeah I think nuclear fusion would in fact happen, unless perhaps the energy radiated by the ball would some how push the air out of the way.

You should watch SmarterEveryDay sonic baseball

Guess the first XKCD reaction video did well ;)

What I have learned from you is that everything is probalistic. So probably there is at least one atom there fusing with the ball.

But nuclear fusion can occur at well below relativistic speeds, at .9c there should be all sorts of nuclear reactions including some fusion

I think you're wrong about the induced nuclear fusion. .9 the speed of light with that amount of mass in that amount of space is more than enough to produce fusion, though I don't think it will be enough fusion to be a significant source of energy for the explosion.

What team do you pull for?

I think where he was going with the "fusion" aspect of this would be that there'd be enough energy to split atmospheric molecules (primarily water vapor) into atomic components, where you'd end out having significant availability of H2, some of which would fuse with H2 liberated from some of the organic molecules (which would be similarly split as the ball turned to plasma). Agreed that standard hydrogen doesn't fuse as nicely as deuterium or tritium, but there should be enough liberated energy to do the job.

Another type of fusion is also in dragon ball, so fun coincidence lol

Try to react to "Molecular shape of you" by A capella science

If welding isn't fusion, what is cold welding?

Yeah but what if the batter swung?

lmao 😂 And the survivors of the worlds last baseball game ever, a man pitched his fastest pitch ever! and the baltimore sparrows? won! 😮 news anchors break out their rule books, um no! this guy would of had a walk and home run because it left the stadium! random camera guy: the whole stadium left you goof! 😂

Doesn’t relativity say this can happen sense it’s not going light speed

If you think that's funny you should check out the one where everyone jumps at Rhode Island.

You have to react to terrence howard on JRE. We need some expert opinion on what he is saying.

You would be cooler if your were residential not commercial lol

Hey there, please watch and do a reaction of the Japanese movie "Fukushima 50". I think it's a great movie to show their perspective of the events of Sendai Earthquake, Tsunami and Fukushima accident.

Hi Taylor folse nuclear can you please react roblox chernobyl unit 3, is a very realistic game about operating rbmk 1000 nuclear reactor

8:02 One piece

Your "not fusion" take is real weird and a huge miss. If two nuclei impact each other with enough energy, they could fuse. XKCD is saying that nuclei would be impacting each other with enough energy for that to happen. If you were to claim the impacts didn't have enough energy, or that the nuclei would not be able to impact each other, that would be at least conceptually compatible as a criticism, though I can't say it would be factually accurate. Saying it's not fusion because there's no confinement is like saying the uranium in uranium ore is not experiencing fission because it's not in a reactor. Some of those atoms are absolutely splitting, whether or not you have put in the effort to make prompt it, to make it usable, etc.