of course antimatter falls down

[@IsaacMayerCreativeWorks]

to quote XKCD: There are four fundamental forces between particles: 1) Gravity, which obeys this inverse square law - F(gravity) = G*(m₁m₂/d²) 2) Electromagnetism, which obeys THIS inverse-square law - F(static) = Kₑ*(q₁q₂/d²)... and also Maxwell's equations. 3) The strong nuclear force, which obeys, uh... well, umm... it holds protons and neutrons together. 4) The weak force. It mumble mumble radioactive decay mumble mumble. Of these four forces there's one we don't really understand. It's gravity.

[@nerdycatgamer]

I never saw the punchline after listing the forces; that's golden. I remember trying to ask my high school physics teacher about the weak nuclear force (we were learning very basic quantum physics so she explained all 4 forces from a conceptual level, similar to this) and i was like 'so how is it a force? what does it do? how do we predict when particles will decay, is it just random?' and she just said 'yes', lmao.

[@tildessmoo]

Don Lincoln at Fermilab actually has a pretty good video about the weak nuclear force. It's mostly about how the mass of the W boson explains why the weak force is weak in terms of the Heisenberg uncertainty principle applied to pair production, but I think it's also a good demonstration of how the weak force is pretty well understood, but extremely hard to explain in lay terms. It's very well understood by particle physicists and mathematicians who read physics papers, but impossible to explain to anyone with only a high school or undergrad math and physics education. The strong force is a little easier (I can _kind_ of understand it, and I think the best video on the subject is by PBS Space Time), and it's sort of possible to understand why it only operates at short ranges at least without a proper physics background. Gravity, otoh, physicists understand _what_ it does (mostly), but not why or how, and even the what breaks down at the Planck scale. This is all from my own lay perspective, of course, so take everything I say with a truckload of salt.

[@mrmadmaxalot]

Moral of the story: If the equation is simple enough to make obvious sense it is only an approximation.

[@jameshart2622]

​@@tildessmoo As someone with physics Ph.D. who took basic QED and stopped (I went in non-particle-physics directions, because even then it was obvious particle physics was in trouble) I'd say you did a pretty good job of summing it up.

[@onehitpick9758]

The weak interaction has been successfully unified with the quantized form of electromagnetism, and is one of the biggest accomplishments of the previous century.

[@bradwilliams7198]

I actually took a thermo class from Fairbank as an undergraduate. Sometime later, a different professor made a remark in a class he was teaching: "Sometimes a theorist will tell you about some phenomenon his theory has predicted, and ask if you can detect it experimentally. Then you do a "back of the envelope" calculation and realize the effect is about 10 orders of magnitude less than you can expect to detect. And unless you're Bill Fairbank, you don't even try."

[@CSpottsGaming]

Signs I'm truly a nerd: I laughed out loud at this. It's such a solid roast, I love it.

[@Nzargnalphabet]

I was completely confused reading that, I live in Alaska and the second biggest town here (which isn’t saying a lot) is called Fairbanks, so I was very confused when you said you took a thermo class from fairbank and then you talked about Bill fairbank who I’ve never heard of, but now I somewhat get it

[@bradwilliams7198]

@@Nzargnalphabet When taking the class, I had to train myself not to add an s to his name! In watching this video, I ended up pausing on the picture of him, to make sure I was getting it right.

[@GSBarlev]

I'm sorry, this is going to sound kind of random, but did he _ever_ describe anything as analogous to beebees swirling in a sink?

[@PeteStMarie]

I about choked on the the cookie I was eating when she said "Michio Kaku would have found it in his garage when he was a teenager" Thanks Angela!

[@Pxtl]

"Michiko Kaku built one! In a cave! With a box of scraps!"

[@breakinglegsandbreakinghea3167]

I don't know a lot about celebrity physicists. What's the deal with Machio Kaku?

[@subterficial]

​@@breakinglegsandbreakinghea3167 I am an IT person, not a scientist, but i believe it's because Michiu Kaku is associated with string theory, which as of now after many decades of research has not produced any testable experiments that aren't already solved by other scientific models. Many string theorists also claim that the reason why most don't understand their theories is not because they are incoherent, but because general researchers are simply not intelligent enough to understand the field. The joke is that string theorists would think the problem is very simple compared to string theory.

[@tomofthetomb]

Make sure to put the "I matter" in antimatter

[@BreezyBeej]

Me saying my daily affirmations to an insect: Ant, I matter

[@photonicpizza1466]

@@BreezyBeej🤣❤️🐜

[@dc9662]

​@@BreezyBeejI needed to hear this today. Thanks.

[@Remiwi-bp6nw]

Positron thinking!

[@colinbrash]

As a member of the Formicidae family I often repeat to myself, “Ant, I matter”

[@MonochromeWench]

I imagine they didn't do the experiment with real hydrogen because it will be very difficult to detect individual hydrogen atoms. Anti-hydrogen nicely annihilates and releases a burst of photons indicating where it went. Normal hydrogen not so easy to detect.

[@bernhardschmalhofer855]

So the next step should be to build the apartus out of antimatter.

[@YTEdy]

That's logical but it's not the case. This is done in a vacuum to measure the rate of falling. This kind of thing has already done with matter to measure how small gravity remains consistent. Light, for example, is quantum. Single photons behave differently than photons as a whole. When done with single atoms, this quantum effect isn't measurable with gravity. The assumption was that antimatter would behave just like matter in gravity, but it's still good to check. That's basically what she says. Her video title doesn't match what she discusses.

[@mehill00]

Protons can be detected quite easily. If they’re over say 20 keV you can just use a biased Si crystal to make a solid state detector (SSD). If they relied on annihilation alone to detect the anti-H it’s true they would have to build a modified set up to test H, but it can be done straightforwardly. They could even stack up a thin and a thick SSD and measure the mass (using the stopping power) to be sure they were counting only H. And these detector systems can be small (few cm) since we do it in space all the time (that’s what I do), where mass and size restrictions dominate our designs, often. If they’re less than ~20 keV kinetic energy they could do something with time if flight measurements and micro channels plates, but I’d just try to use more energetic stuff if possible as SSDs are cheaper and easier, don’t require high voltage, etc. If a single detector system could measure the pions produced in the annihilation for the anti-H test or the H directly, that would be cool.

[@simontillson482]

@@mehill00That’s great and all, but aren’t the hydrogen (or anti-hydrogen) molecules really cold, and therefore moving with a tiny velocity, so that they at least have a chance of falling out the bottom before hitting the sides? I didn’t think an SSD could detect particles moving that slowly. I was rather thinking an ionisation detector might be more suitable, like the ones used in vacuum gauges? Edit: Oops - somehow I didn’t see the latter part of your comment. I guess you thought about the low kinetic energy issue.

[@mehill00]

@@simontillson482 I haven’t read the paper, so I’m not sure how energetic these particles are. I thought I saw in one of the freeze-frame text boxes that the anti-H were ~100 keV. If the dimensions of the problem work out such that the atoms have to be much below ~1 keV my expertise breaks down a bit. My inclination would be to try to set it up the experiment to make the particles measurable using a method that either I know well or seems to be well understood by others I could work with.

[@scottrobinson4611]

This really captures the essense of science for me. Setting up an extremely complicated, challenging and exoensive experiment to verify an "obvious" result, because we hadn't explcitly checked before, and *just maybe* an unexpected discovery would come from it. We could have just not done this and everyone would begrudgingly accept the argument "of course antimatter obeys gravity"... But it's nice to be really sure, even if it was a very difficult task. This was a really good video, Angela!

[@OhhCrapGuy]

Exactly. Checking the obvious is extremely important. After all, it was *"obvious"* that heavier things fell faster for 2000 years. Until someone (Galileo?) actually checked to make sure that heavier things fell faster. Imagine if they did fall faster, everyone would have said "why did he bother even checking, obviously heavier things fall faster!" But he wasted his time and checked the obvious anyway. And it turned out heavier things DON'T fall faster!

[@robertaylor9218]

Yeah, this is why I was frustrated they didn’t do the experiment with hydrogen yet. Maybe the values aren’t exactly the same.

[@ijpg-fd7qn]

One reason this experiment is so awesome is that its taking the very first physics experiment you do ever, dropping a small ball and a big ball and seeing which one hits the ground first, and scales it up to 11. Lets take the tiniest, weirdest ball we can find and see if it still falls the same way. It's so simple yet it took years and years of effort and knowledge to even attempt for a result that is the most intuitive thing in the world. There's just something really satisfying about that idk

[@chrisdsouza8685]

"You just have to check." Reminds me of the math professor who began the lecture by writing an expression on the board. Then he turned to the class and said " That, ladies and gentlemen, is obvious." Then he turned back to the board and froze. After a minute he said "Excuse me" and left. A couple of students followed him, worried, and they came back to state that he was in an empty classroom, furiously writing on the board. An hour later, he came back and said ",Yes, ladies and gentlemen, that is obvious."

[@ExecutionSommaire]

Angela is the kind of professor I would have had a moral duty not to procrastinate the homework

[@der6409]

I imagine I'd shrivel up into a dried bean if she ever looked at me in disappointment over not doing an assignment.

[@ubahfly5409]

OMG yeah, the type of professor where you're motivated by a mortifying fear of disappointing her.

[@fmdj]

she's the kind of professor I'd be sad after each class because it's over so soon

[@laincoubert7236]

@@der6409 i'm sure she'd say "it's fine"

[@rwm1980]

Such strange nerdy lads

[@FernLovebond]

I understand only a fraction of most the content you produce, but I *love* your delivery and passion for the subjects. The nearly-deadpan excitement is just glorious. And you often explain enough for me to get the gist. It's wonderful. _You're_ wonderful. Thank you!

[@ryandonavon7451]

hey there, good to see you here! Yes she is great!!

[@Bassotronics]

I’m one of those wonderful persons who love science but can’t do even basic algebra. I love her views and explanations on different subjects. Everything she says is correct unless someone else says otherwise.

[@IanStreet]

Of course patron names scroll up…but if there was ever a video for a list to fall from top to bottom of a screen, this would be it. Happy I discovered this channel last year. Science communication done well.

[@georgelionon9050]

patron names are anti mass

[@WindsorMason]

Supporters help take some of the weight off.

[@paulmalone216]

Antipatrons scroll down according to my theory

[@pumellhorne]

​@@paulmalone216antipatrons are Angela's neighbours who start doing noisy yardwork while she's recording. If they come into contact with a patron they'll annihilate

[@ICanDoThatToo2]

@@paulmalone216Dr. Collier is surrounded by a cloud of virtual patron/antipatron pairs, some of which escape to become real patrons.

[@RealHypeFox]

"You just have to check" Which is exactly why I still put 2 + 2 into the calculator. Maybe something changed and I wasn't aware.

[@cookechris28]

Went out to get groceries half an hour ago, forgot to lock up the house. Gotta check on the calculator. Maybe somebody made off with my 2+2 and turned it into 3 somehow.

[@chuckgaydos5387]

I never thought of checking with a calculator. I've been rereading Whitehead and Russell every morning.

[@mallninja9805]

2+2 _can be_ 5, for large values of 2. It's always wise to check.

[@henrytjernlund]

Well 1 + 1 = 3 far vary large values of 1. 🙂

[@nitesy381]

If 2+2 is wrong, there is a problem somewhere.

[@coleb.t.6905]

I’m a musician with little calculus knowledge, but I came across your channel a year ago, and have watched all of your videos because you are such an amazing story teller. Keep up the good work

[@michael1567]

I cannot overstate how fun it is to learn about physics the way you make videos

[@21stCentDissonance]

I was a PhD at CERN working in the antimatter factory where ALPHA-G was located. I worked for GBAR, a rival experiment but given the small amount of physicists in experimental antimatter physics there is a lot of overlap of staff as they rotate through contracts. ALPHA was always likely to be first to report because they were adapting the original experimental apparatus that was used just for trapping antimatter atoms. The question for ALPHA G was could they get enough statistical validity and resolution to get the result. AEGIS and GBAR went the other direction, building apparatus that would have very clear resolution of but only the direction \bar{g} but the magnitude of it. ALPHA G's results in 2017 were looking hopeful but they were working out the simulations for the magnetic fake gravity. I was at the Royal Academy conference when Geoff (or maybe Jeff) explained their approach and it was one of the more interesting presentations

[@kunibald128]

Thank you for the additional context. The results shown here do seem quite inconclusive when it comes to the magnitude, so I am happy to learn that there are also complementary experiments with a focus on that.

[@barefootalien]

@@kunibald128 Surprisingly hard not to hope for another "crisis in cosmology" style progression where the error bars narrow more and more, isn't it?

[@oddbirdMusic]

I'm delighted to discover that "antimatter factory" is a workplace that exists.

[@A2ne]

Principia Mathematica reader disappointed that 1+1=2

[@Rkcuddles]

I love how instead of trying to teach science, you tell us about how science kinda works. Oh also, we leave comments because we want the algorithm to boost your content because we are engaging with it. We want you to succeed because we wish more people knew how science works

[@emenesu]

​@@deltalima6703I care.

[@dirtdart81]

Well said. The more and better science communicators, hopefully a more scientific literate population will exist

[@mehill00]

I’m so glad you said they should’ve done Hydrogen too. I’m an experimentalist and I think this is a strong comment pointing out an important weakness. Not saying the work shouldn’t have been published, by any means, but it is the first thing I thought of: why are they comparing to simulations?! I hope they will follow up with both H and anti-H. If I were the referee I would have made sure they addressed why they didn’t do the H test as well (I imagine there’s a good reason; and I haven’t read it so I’m just assuming they didn’t address it or you would have mentioned it). Thanks for continuing the great content!

[@21stCentDissonance]

Can't detect hydrogen in the apparatus ALPHA-G uses for detecting anti-hydrogen. Anti-hydrogen annihilates which gives a very strong temporal and spatial signal. Hydrogen does not so would require a very different apparatus and setup.

[@ho77iday]

This is my favorite channel on youtube. Period. Full stop.

[@go-away-5555]

Ah, but how do we know it doesn't fall anti-down. Please listen to my lecture where I disprove physics by making basic math errors.

[@PurpleShift42]

nice nice nice (it says something about the prevalence of physics cranks that this is even a possible joke that means something)

[@dhwyll]

Mr. Howard? Is that you?

[@Rio-zh2wb]

lmao

[@asdfasdf-dd9lk]

omg this is really cool, I was a summer student during my masters and worked at ALPHA in 2022 just before the big ALPHA-g measurement, it's awesome to see you make a video on it c: ive not finished the video yet, but if anyone has any questions im more than happy to answer them, to the best of my ability (and bearing in mind that im farrrrr from an expert)

[@regards2jimi]

I’m glad you managed to survive the shift schedule

[@asdfasdf-dd9lk]

@@regards2jimi hahaha yeah ended up with a horrendous amount of nights courtesy of niels, was a really great time though :)

[@izzygrosof]

About how many people do you think were working on this project at a time? Really cool work, well done!

[@martinwhitaker5096]

To my basic reading the graph and text conclusion suggested they experienced 0.75g rather than 1g.... did I read that right?

[@asdfasdf-dd9lk]

@@martinwhitaker5096 yes, but the error bars pretty comfortably overlap with the 1g measurement. Also, as she mentions in the video, this is sort of a statistics based approach: the anti-hydrogen that is trapped has some temperature (meaning each anti-atom is moving randomly in some direction at some speed), so when it's released what you actually measure is the fraction of anti-hydrogen that annihilates at the bottom, vs the top and so on. Since this initial motion is thermally distributed (essentially randomised), this means that for small enough numbers of measured annihilations, the measured value of g can be pretty different from what the anti-hydrogen actually experienced.

[@FrancisFjordCupola]

On Dirac's anti-matter and/or/versus anti-gravity... basically Dirac found a solution with x-squared and since minus times minus equals positive, he tried to get rid of the minus result and could not and then stubbornly accepted that it might indicate the minus variant is physically real. Whereas the string theory crowd goes "hey this is just like Dirac."

[@GSBarlev]

Another experiment shooting holes (🥁) in Dirac's Hole Theory! I love how you explain the need for experiments when the math says something is "not _not_ allowed." Also: cool to see a shout-out to William Fairbank. His wife, Jane Davenport, was also an accomplished physicist-I know a decent amount about them because their son is the CEO of my former employer, Capital One.

[@CRJessen]

I really appreciate your videos. Keep up the good work.

[@YyNRCyY]

for reaal. I stumbled upon her physics books video because everything listens to me and knows that i have physics classes now. I binged a lot of her videos. they're great

[@harrybarrow6222]

Of course you check the veracity of statements made, even by eminent people. “When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.” (Arthur C Clarke) The motto of the Royal Society is “Nullius in verba”, or loosely “Take nobody’s word for it”. Aristotle said a lot of things that were taken as true, until the 17th century when people began to test them - and discovered errors. Many exciting discoveries were made when assumptions were checked, as in the Michaelson-Morley experiments.

[@erebology]

Nice catch with Maxwell's take on gravity! ❤

[@babynautilus]

yeah that was a really intrinsic sort of way to think about it 🤯🎉

[@Phys1nk]

I'm in biophysics. I turned on your video to have some background noise while I reviewed some notes. No notes were reviewed. I love your vid, your enthusiasm for science is few and far between

[@SecondEllis]

I can't believe I'd never heard that snippet you read from Maxwell. That was a perspective I needed for some real intuition to fall into place. Thank you!

[@jeffbowermaster1568]

At 24:33 you ask them to repeat the experiment with protons & electrons. I think the reason they didn't is it's hard to detect atoms of hydrogen. Anti-hydrogen gives off a signal when it annihilates. Hydrogen doesn't annihilate.

[@scottrobinson4611]

Technically, antimatter doesn't just annihilate on its own either. Annihilation occurs when a particle meets its anti-particle. Anti-hydrogen + Anti-hydrogen = nothing happens Same goes for Hydrogen + Hydrogen. You need Anti-Hydrogen + Hydrogen (or Anti-Hydrogen + a proton + electron) for annihilation. The reason the trapped anti-matter annihilates is because the surrounding experimental apparatus is made of matter. We could trap hydrogen in the same way and have it annihilate if it was surrounded with some anti-matter, but that's a lot more work.

[@CedarAce1000]

I would imagine that the reason they didn't do it with matter hydrogen is that the experiment relies on detecting the annihilation of antihydrogen against the device, whereas hydrogen obviously won't annihilate :)

[@crackedemerald4930]

They should've made the anti-device. Which is obviously the same device but out of antimatter and upside down

[@pressaltf4forfreevbucks179]

​@@crackedemerald4930💀💀💀

[@potatoshamcakes]

Getting out my popcorn for another science video that mostly goes over my social science ass head but I'm here for the ride

[@ProteinShowdown]

same, I'm a concert pianist who couldn't pass chemistry or physics but here I am

[@orterves]

It is awesome to have a trustworthy and well presented resource to point to if someone asks questions about this stuff though - "I don't know, but here's a link from this great KZbinr you'll like who does!"

[@potatoshamcakes]

​@@ProteinShowdownI was slotted to take honors physics in high school and they messed up and some how gave me an A so I haven't taken a physics class sense middle school and that was like 14 years ago lol

[@kombatwombat6579]

Yo, make space. I got milk duds.

[@Phroggster]

​@@kombatwombat6579Milk Duds? Get this person to the front of the line.

[@michaela.delacruzortiz7976]

Angela, people still talk about anti-gravity because it's a cool thought. The idea that if it was possible and we studied it enough we might just be able to harness the force of gravity to do cool things like perhaps....(recreate what the sun does to make energy, make the process of getting to space from earth or any other planet "different", possibly create houses that are upside down, or vehicles)....or any other of that type of jazz. I think that engineering wise, there would be allot of interesting applications to a "true" anti-gravity system. Yup.

[@sjswitzer1]

“Michio Kaku would have done it in his garage when he was a teenager” is just perfect. No notes.

[@harrybarrow6222]

Checking whether antimatter falls down or up has cosmological implications. We wonder why the universe appears to be made solely from matter. Where is all the antimatter? If antimatter fell up, then there is repulsion between matter and antimatter. That would suggest that there could be equal amounts of the two - but they separated through repulsion and are now at opposite ends of the universe.

[@brianl7321]

As a math person I loved hearing you explain this. It's like someone saying "well of course 2 minus 2 is 0" but no one being able to *prove it* for 50 years and now finally having a proof for it.

[@zemm9003]

Even if antimatter would curve spacetime differently than matter it would still "fall down" since the geodesic equation is completely independent of even the existence of mass (which is why photons follow them regardless of being massless).

[@Tahoza]

A fellow fan of the Corning Museum of Glass I see. Their channel has a lot of very satisfying and educational videos.

[@infinitivez]

Hello from Dr. Dave! Found you because Dave did a vid about Formscapes and he had mentioned you in some rubbish video of his. I love learning about science stuffs, and so glad to collect yet another person willing to put create science content on youtube! TY!

[@FrancisFjordCupola]

I, too, was like of course anti-matter falls down. Did not expect anything else. But... then again that is only my intuition and the whole universe does not have a single obligation to adhere to my intuition. Therefore, I think it is very, very, very cool if we can check and be sure. Just in case. Besides, it's a good excuse to look somewhere and we don't what else will turn up. Even if I expect nothing else. Only one way to be sure. I hope that if builds extra experience handling and working with anti-matter. Which is helpful with more difficult experiments.

[@jeffguarino2097]

Never trust intuition. Intuition is a very flaky concept.

[@Digital-Beef]

I really appreciate that we have a paper describing in exact detail how they dropped some antimatter to see if it fell and it did.

[@seijirou302]

I always love the substance of your content, but I just have to say that I adore the little Casio cuts and how they're always something different and they're always bangers. That's all, hope you have a wonderful day.

[@wbwarren57]

Thank you for what is undoubtedly the definitive definition of physics: Physics == poking the universe with a stick!

[@mrhassell]

If it falls up, you win a Nobel Prize. If it falls down, people tell you 'I told you so'. - Prof. Jeffrey Hangst

[@chloe_chung]

If even antimatter falls down, How do we stand a chance? Squatting in a well at stars, Forgotten romance. A wrinkle in my eye helped me to touch the sky Heart broken open into peaces on this plane Met my anti matter self and dissolved into pure light.

[@ytpanda398]

One of my professors is a lead scientist on this experiment and it's cool as hell

[@billhurt3644]

Science Daria strikes again. Amazing video. Amazing sense of humor and editing. Amazing science content.

[@cletus2580]

You make science fun and interesting. No nonsense, I learn every time I watch a video.

[@abrarrauf3801]

Another really good video!! What I particularly liked is your read through of Maxwells thoughts on repulsive gravity. It's always so fun to see people at the cusp of fundamental discoveries in physics grappling with concepts that we take for granted today!

[@Daiyuki117]

But what IS down? Vsauce, Michael here.

[@aelolul]

"Which way is down? and how much does down weigh?" - I may be misquoting but I am pretty sure he starts off a video with that.

[@Clayne151]

Simple, ask an Aussie which way is down. Then its the other way.

[@richardgray3343]

I could listen to Dr Angela all day. I love her teaching style and she's so funny and honest. Wish all my teachers where like her... If only! You would love County Durham to teach..x

[@yudeok413]

Sci Show yesterday : Does antimatter fall? 😮 Angela today : of course antimatter falls down 😂

[@Tyler.8046]

30:00 - While I absolutely don't want to discount how incredible and intellegent Einstein was, I think this really shows that people maybe put him on too much of a pedestal. He was standing on the shoulders of giants. While he absolutely deserve the credit for special and general relativity; it just shows that if it wasn't him, it would have been someone else. We were nipping at the heels during Maxwells time, he just need a few more steps to make it there. Every individual scientist is so incredibly important to the field and it's beautiful how our models fall out of the science we do.

[@Tyler.8046]

Also, in response to those articles at the end, could you imagine how catastrophic it would be to our current understanding of Physics if particles with mass were repelled by gravity.

[@naomimoore47]

I agree, the big leap forward was Maxwell's interpretation of the electromagnetic forces, he was a genius. It took an abstract mind like Einstein to hold those ideas in thought experiments and play them out in the greater universe. They should get equal credit for the creation of modern physics.

[@mjr_schneider]

Ok but how fun would it have been if we lived in a universe where antimatter falls up. I feel like that would be just a way quirkier and therefore better universe, personally.

[@ps.2]

And would neatly explain why the observable universe seems to have little or none of it. We've been looking _around_ for all the antimatter but we forgot to look _up._ It's been collecting on the ceiling this whole time.

[@jeffguarino2097]

There is still hope. Antimatter could gravitationally repel other antimatter. This would mean it would not form planets and stars but be dispersed out in to space. That is why you don't see any antimatter.

[@benjaminzaugg1127]

Maxwell left us on a cliff hanger

[@throckmortensnivel2850]

I'll just add my voice to the chorus of approval for Dr. Collier's videos. I have seen many of them, and have not been disappointed. Entertaining, ecucational, and a bit humourous. This one is just another winner. Carry on!

[@Metronics]

Long time ago in Mexico there was a crazy guy from UNAM who wrote a thesis on repulsive gravity. He was really convinced of it!

[@jmarinotripp240]

Alcubiere?

[@coriollis]

pasa chisme

[@georgelionon9050]

which is fine, this is how science works, you must just be ready to be disproven. (or better yet try to proof yourself)

[@asbar1515]

Your enthusiasm is infectious, cute, and makes the video more fun to watch. The delivery of the material was awesome and I learned a lot, so ty. This IS a really cool experiment (OF COURSE IT FALLS DOWN). And your Love for String theory is always fun to see.

[@irober02]

"Antimatter" is not a very good name for antimatter. In common parlance, I think mass is the property most closely associated with matter so, if you call something antimatter surely the most obvious (but wrong) implication is the mass is negative. BTW I'm looking forward to reports of anti-dihydrogen (or should that be di-anti-hydrogen).

[@AnonymousAnarchist2]

You are correct. I personally think "mirrored matter" or "reversed" "Negetive" has the same issue as "anti" But "anti" and "negetive" have the advantage of immediatly drawing the connection to antimatters most immedeatly observable trait. It destory's an equal mass of matter! I think English is just too binary to express the physical world accuratly; an unintended side effect of adopting the Guettenburg press and typeface. (for those who dont know; Engilsh, and most European languages changed dramatically by using words that used the alphabet that was shared with the German presses typeface as replacements. Wife is a good example, it used to refer to a man who was homely and perfered the company of a man and a feminine style of dress, homely is another it used to mean what it said on the box a home maker...)

[@coolsenjoyer]

I agree that the "anti" part can easily give false impression of the properties of the stuff but at the same time I kinda think its the perfect name for something that can't really coexist with the matter we are all made of

[@21stCentDissonance]

@@AnonymousAnarchist2 the first person to hypothesise it called it 'contraterrene matter', i.e. non Earth-like matter.

[@MikeCnolan]

Love the statement about the scrolling software :). Will look for your patreon, but here for the nonce.

[@LampDX]

Excellent summary as usual! I think a lot the confusion for people guessing antimatter might key to antigravity is mostly due to the name we gave antimatter. When you get down to it, the only thing “anti” about antimatter is the fact that they carry the inverse charge of the particles we commonly interact with, which it coeliminates as a result. There’s no fundamental inversion of any extrinsic properties besides that. “Antimatter is matter” is something people should hear more often!

[@psymar]

well, and the fact it annihilates with normal matter. Also I vaguely recall a particle interaction that's been shown to have chirality that's reversed with antimatter. A better explanation is that antimatter is regular matter, in a mirror, going backwards in time.

[@ZabivakaPirate69]

​@@psymar How is it going back in time? That sounds like something that Angela would read then pause and look at the camera as she sighs.

[@ByzantineDarkwraith]

@@ZabivakaPirate69 she literally did almost exactly that in her previous video on antimatter

[@ByzantineDarkwraith]

@@psymar particles of normal matter annihilate with their own anti-particles as well, that’s not different. There are other things that are different, but you didn’t mention any of them.

[@bestaround3323]

If we want anti gravity we need negative mass, not anti matter. Which probably doesn't exist. The equations technically work with negative mass, but it had some wonky properties.

[@brandonthesteele]

34:10 Love that media websites are so incentivized to drive clicks and attention using emotive headlines that they feel the need to lie about the content of the article, thereby spreading blatant misinformation. Good system of incentivization there, it totally doesn't beg to be destroyed every day.

[@pauforcadellcampos4452]

Your videos make my day Angela, thank you so much :))

[@pbezunartea]

Your enthusiasm is contagious! I had to watch the whole video!

[@icansciencethat]

Great video... you asked them to do the same test with regular hydrogen. You probably realized it right after you said it, but there's a very good reason why they didn't do that. Anti-hydrogen escapes the trap and is detected... how? Because it annihilates creating a detectable flash. Regular hydrogen doesn't do that... it's much harder to detect a couple hundred hydrogen atoms doing anything.

[@Terigena]

Just make an identical machine out of anti-matter. Simpels.

[@lucasng4712]

nah

[@hearstboy]

Why did people think anti-matter might fall up? Simple... anti-matter behaves opposite from matter in other interactions. In the minds of people who don't know better (myself included), mass is just one of many properties among the likes of charge, spin, colour. If an anti-matter particle can have the opposite charge, spin, colour from it's matter counterpart, why not opposite mass? This is why there's value in doing these experiments. I mean, how many times have people come up with conjectures about things in the world, done the theoretical analysis not knowing what biases they've injected in their model, only to later have experiments completely invalidate the theory?

[@Kraflyn]

Probably because of the Dirac Sea interpretation. Vacuum is normalized to have zero mass and charge. Once you create particle, you pull it out of vacuum. this creates a hole in vacuum. So the conservation of charge requires particles and antiparticles have different charges. But mas is conserved too, so the mass conservation would require antiparticles to have negative mass, if the Dirac Sea interpretation was correct.

[@jbradfield]

presumably if you were going to design an equivalent experiment for normal hydrogen, you wouldn't be super concerned about exactly *how* you detected the hydrogen so long as you *could* detect the hydrogen, but as a thought exercise it's very silly to think that the hardest thing to replicate exactly from the antimatter experiment would be the detection apparatus, since hydrogen won't annihilate just from bonking into the side of the tube

[@JasonAStillman]

What a great sense of humor, love it!

[@the_blocklord9341]

38:00 "in this paper, they mention something I've never heard of: the microscope" -dr. angela collier

[@GustavoValdiviesso]

I LOVE the waterfall you used for the cover. I visited it too many times to know it from a glance. Either that, or there are too many waterfalls look-alikes around the world.

[@G3rain1]

"Observation of the effect of gravity on the motion of antimatter" this is cool and all, but I would find the opposite question far far more interesting. That is : "Observation of the effect of antimatter on gravity". In other words, which way does antimatter curve space time? Which would be way more difficult to test.

[@blank_3768]

the same way normal matter does.

[@judmcc]

When I was an undergraduate in the mid-1970s, I wondered about this. The professors said that antimatter did fall like regular matter.

[@coriollis]

as a theorist in training I'd love it if antimatter didn't fall down. new physics!! I _am_ kinda disappointed that it does

[@AlanTwoRings]

If the electric field is too dominant for charged particles then just measure the gravitational effect on an anti-neutron 😎

[@drumskateart]

yes! the problem is just about how to capture the anti neutrons since it also is not affected by magnetic fields lol

[@christiaankoningen4632]

free neutrons are not stable particles and will decay over a short amount of time (mean lifetime is about 900s) so probably not a good idea

[@drumskateart]

@@christiaankoningen4632 are you sure we can't get a peek of how they fall down in the 15ish seconds they stick around for? i bet their decay products are a good way to detect where they end up after they fall :)

[@deheavon6670]

Free neutrons would decay before you could do the experiment, though. And if you could male enough of them fast enough to run the experiment, you could already have done it with anti-hydrogen.

[@simontillson482]

Yeah, one issue is that they explode. The other is they’re extremely hard to make in the first place. The only way I can think of to synthesise an anti-neutron would be to perform fusion using anti-hydrogen. We can’t even do that with ordinary hydrogen!

[@bobiboulon]

37:10 With that music, the hand gesture... I don't know, my brain assumed you were going to rap some sick lines summarizing your video. I must admit thatt a part of me is weirdly disapointed. :'D

[@Rudenbehr]

literally can listen to her talk about physics all day

[@dameonvonfrankenstein3001]

I don't understand how increasing the magnetic field changes the local gravity. Wouldn't the measurements then be measuring how the material is interacting with the EM field and not gravity? wasn't the point of the difficulty of the experiment how complex the problem of EM interference was?

[@Seven-Seas-of-Baba-O-Riley]

I never really understood why mathematicians would always make these long and complicated proofs for things that were so obviously true, until 8th grade. I was in a special help math class, and we had a long term substitute who had not taught math for a very long time. We were learning about slope, or y=mx+b. I don't really remember how it all works anymore, but I'll do my best to explain it for anyone who doesn't understand it already - (So imagine a grid with a vertical line running down the center labeled y, and a horizontal line in the center labeled x. You'd be given a line that runs through the grid, and your goal is to use a function to describe where the line is, and where it is not. The line is always Straight. In the function, y=mx+b, m accounts for the angle of the line (so if you Imagine the small squares the grid forms, does the line go from the top left corner to the bottom right, or to the bottom right of the next square down, or the third down, or the third down and one to the right?), x and y equal the coordinates of a specific point on the line, and b accounts for the vertical placement of the line.). At the time of the sub, we were learning how to deduce the value of b when we are only given the values of m, and the x and y values of a single point. Now, the way b was explained to us was that b was the y value when it is on the y axis, so my first thought was y=b when x=0, because the y axis is placed on zero, but when I told the sub this, she told me I was completely wrong. So because I have no control over my own stubbornness, I tried to prove her wrong. She actually got the problem wrong using long division, but she wouldn't accept my answer without proof. Now, the way solved it was to literally trace the x coordinates back to the y axis, which I was able to do in my head, so the only way I could show my work was to write out every coordinate from the point we were given to the point where x is 0, which took me until my peers had left for lunch. She admitted I had the right answer only when she realized the mistake she made in her equation, but she still claimed I was wrong that y=b when x=0, because I had no proof. So every class we did this - she'd get the answer wrong, I'd say so, she'd deny it, I'd stay after class to prove it, she'd admit she was wrong (but only to me and not the rest of the class the next day), tell me my method can't work every time, and repeat. The entire time she was there, she never let me turn in a test without filling the pages with coordinates, she never admitted my way worked, and I never learned how to do long division. She did think I was the smartest student in the class, which somehow resulted in me getting booted into a normal class that was an entire unit ahead. I had no friends, no idea what we were doing, and I still can't do long division. So because people like her exist, we have to prove that 2+2=4, and that antimatter falls. You know what, I take it back, I understand this crap better now than she did then, damnit man, school failed me.

[@Robert-dB]

WTF! "y=b when x=0" is by definition. That sounds like she didn't understand algebra; wasn't she _supposed_ to be teaching it!

[@idontwantahandlethough]

Oh god, that's so rough. FWIW, I'm pretty great at math and I can't do long division either. I mean I can figure it out again when I need to (I bet you could too), but yeah long division sucks 😂

[@stevenklinden]

That sounds incredibly frustrating, but with all due respect, that's NOT why we have to prove stuff like that 2+2=4 and that antimatter falls down. It's not about convincing stupid people (if it were, it wouldn't be worth the time, cost, and effort). The reason people spent time, a century and a half ago or so, "proving" that 2+2=4 was to show that, contrary to Kant's idea of the synthetic a priori, arithmetic is just logic plus an appropriate set of definitions. And the reason ALPHA proved that antimatter falls down is that we didn't actually know that yet, even though it was thought overwhelmingly likely, and therefore was worth confirming.

[@bestaround3323]

I mean long division is just dividing a number as much as you can, adding a zero to the left of the remainder, dividing that as much as you can, rinse and repeat. It is mainly tedious. Which can describe a lot of math by hand. Edit: I now see why some people find long division hard. It requires a solid grasp on quite a few math skills I take for granted.

[@stevenklinden]

@@bestaround3323 Yeah, but proving from first principles (i.e. pure logic plus an appropriate definition of numbers) that this algorithm WORKS and gives the correct answer is much more difficult. Hence Russell and Whitehead spending hundreds of pages on preliminaries before they were in a position to prove that 1+1=2 in their Principia Mathematica.

[@ThatDrummaDave]

So much of this goes over my head, but I still love your videos because you do such a stellar job of communicating complicated subjects.

[@Blackmuhahah]

I always thought it was for historical reasons that they get lumped into one... From before the formal treatment of antimatter in QFT where the negative energy solutions to the Klein-Gordon (this equation would probably be an interesting video topic also in connection with how Schrödinger dismissed the relativistic KG equation because of the negative energy states) and Dirac equations gave us things like backwards in time travelling electrons and the anti electron as a hole in the Dirac sea. I thought someone just said "ah neat, negative energy means negative mass... I bet it pushes odinary positive mass matter" and a journalist did the rest.

[@anuj68]

"so those anti hydrogen hang out in the trap" is definitely in my top 10 favorite sentences 😂

[@Palozon]

That "OK😐" at 30:49 is great.

[@JohnSmith-ju1gi]

I wish I could teach everyone to think the way you do. The most important concepts that have helped me in multiple careers are also your mantras. E.g. "You have to check" is one. And I am especially impressed with your.comment that CERN should have run experiment on Hydrogen as a control I know you are a theoretical physicist but if you decide to do anything else, you would also be a superstar in that. Do not limit your ambitions exclusively to theoretical physics. Your are young and opportunity is endless

[@xtieburn]

I guess the angle some of the articles were coming from is: Wouldnt it be more exciting if they found and empirically verified a crack in general relativity? Though I suppose it is cynical to label this as disappointing rather than just less thrilling, and given the chances of such a thing happening, the fact it didnt probably should have been a foot note rather than the thrust of many of the articles. You know, itd be thrilling if a winning lottery ticket landed in my hands, but given Ive never played the lottery Im not disappointed it hasnt and wouldnt make a habit of talking about it to everyone.

[@unvergebeneid]

It bothered me so much that we didn't know this basic fact about antimatter. So when I first learned about this result from the CERN KZbin channel, I was like "wait, is this it? We finally know? And I'm randomly learning this from my KZbin subscriptions? Why wasn't this on the news? Heck, why didn't anyone call me?!"

[@theCodyReeder]

The next test is to gather enough antimatter into one place that tis gravitation can be measured. Does it pull or push things away?

[@AfonsoCL]

What do you mean? We know its properties. It has mass the exact same way "normal" matter has mass; therefore, why in the world would it "push things away"?

[@tildessmoo]

I'm sure there's a better way than the Cavendish experiment, but right now I'm picturing vials of antilead for the small stationary weights. Even leaving aside how difficult it would be to make antilead, to actually imitate the original Cavendish experiment would take over 1½ kg of antimatter! I know, we'd be using a more streamlined modern setup with lasers and much smaller weights (and probably vials of antihydrogen for the small weights, then subtract the effects of the mass from the matter of the vials themselves), but just imagining someone building a torsion scale with 1½ kg of antilead seems hilarious to me for some reason.

[@paradiseexpress3639]

ain't no way

[@kevinmoriartyphotors]

you haven't understood the nature of antimatter.

[@rakino4418]

​@@tildessmoowhat are you making the vials out of?

[@zmadscientist]

a different view - I recall reading about Feynman diagrams and the statement that positrons could be viewed as electrons moving backward in time. Viewed from this perspective, positrons (as electrons moving backward in time in a gravitational field) should fall UP!

[@MeppyMan]

I always just assumed that the amount of antimatter in the very “beginning” was just slightly less by random chance. But this was enough to cause it to never get going, and matter to take a foothold.

[@EinsteinsHair]

Sabine Hossenfelder said something similar in a recent video, and she's a particle physicist. But most physicists take the view that early on the universe was just energy, and that energy should have formed equal amounts of matter and antimatter. I'm trying to accurately repeat what both sides said in only a few words.

[@senefelder]

In our theory, the relative number of matter and anti-matter is one of the initial conditions of our differential equations for the universe. We pick initial conditions of differential equations to match our observations. No need to further explain it. That is the explanation when it comes to initial conditions.

[@MeppyMan]

@@senefelder your answer did nothing to further my understanding understanding and just made me not want to continue the discussion. Maybe approach things differently when trying to share knowledge and explain things to people. The trick is to not try and sound like you’re the smartest person in the room.

[@sneakyviewing4391]

I love your rants. Sometimes it's like, hearing the same stream of consciousness inside my own head from someone else. Thank you for your content.

[@ChaosPootato]

Maxwell is a legend

[@therealpbristow]

And he had a silver hammer! There's a song about, and everything! =:o}

[@shitpostfella5528]

I'm absolutelly in love with that 2.5D histogram

[@boredstudent9468]

I'm not an expert of that field either but I don't think that experiment works 1to1 with regular hydrogen. Based on your description it relies on the annihilation to measure the individual Atoms, so if we did it with normal Hydrogen we'd need the detector to be made from antimatter to annihilate the falling atoms. Which is quite obviously impossible (currently).

[@garak55]

We can measure the normal hydrogen in other ways that don't require anihilation. Also, we *know* that matter falls down.

[@boredstudent9468]

@@garak55 I just said it's unlikely you could put it next to eachother 1 to 1 But while we are at it, just out of curiosity, how do we measure single Hydrogen atoms ?

[@garak55]

@@boredstudent9468 but it's an interesting question nonetheless

[@GFlCh]

Exactly... I also thought why didn't they test "Regular" Hydrogen as well? Then if the results for one was 0.75 +/-Er1 +/-Er2 and the other was 0.92 +/-Er1 +/-Er2, that might infer or indicate something, while both at 0.75 +/-Er1 +/-Er2, perhaps something else... Missed opportunity. Awh... Love your videos!

[@testostyrannical]

This is such a good channel.

[@ShirleyTimple]

Indeed

[@GolyBidoof]

i saw the thumbnail alone and that quote with your voice already started ringing in my head 10/10 title, 10/10 segment at 2:03

[@kasel1979krettnach]

ironic that the only thing not anti in antimatter is the actual matterness of the matter : it's mass 😅

[@puernatura8998]

31:50 I don't think you understand just how amusing your description of the scientific process is here. "You need to observe it, you need to touch it, and poke it with a stick" might be one of the best things you've ever said.

[@notverygoodguy]

Bettered by "I'll insert that clip when it becomes available" after explaining how a writer would deal with her friends enjoying talking to her about Star Trek.

[@CorbiniteVids]

Never miss a chance to come for Michio Kaku

[@Artyomi]

Angela somehow sounds like she is perpetually saying something sarcastically but at the same time with so much genuine passion - and I love it