Why Protons Can't Travel Faster Than This Speed

The special theory of relativity tells us that nothing can cross the speed of light. Sadly for protons the limit is slightly lower than the speed of light.
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[@lastchance8142]

First timer here. Really appreciate that the topic is not "dumbed down" like so many other sci-sites. Showing the math makes all the difference! Suscribed...thank you.

[@Hans-ChristianSchwartz]

Seconded

[@zebo-the-fat]

@@Hans-ChristianSchwartz Thirded!

[@narfwhals7843]

First I thought you made a typo and this video would be about why massless particles must travel at c. I had never heard about this GZK limit. Thanks for this new info!

[@General12th]

"Why can't protons travel faster than this speed?" "You... you meant photons, right?" "DID I STUTTER?"

[@johnnym6700]

@@General12th There is no such thing as a photon - Ken Wheeler

[@Leonard-yi9fd]

At 0:40, the principle of relativity is WRONG! When you have two objects where the one is moving relative to the other, it is not that each of them is stationary in it's own frame of reference and it is the other that is moving. In fact there is an absolute frame of reference where each object has an absolute velocity, it is the COMMON CENTER OF MASS of the two objects! The common center of mass is the stationary - absolute frame of reference! Therefore every object has an absolute velocity with respect to the center of mass of the universe! Do not believe anything the called "professors" tell you, the purpose of all this is on the one hand financial benefit that they have from all this fairy tales such as the theories of relativity, quantum mechanics etc. On the other hand is that they are trying, even if the most of them don't understand, to make the people as stupid as possible, so they can take full advantage in mankind! That is, they want people like dogs to not resist anything! After all, it is not accidentally that most of those who "lead" humanity are jews. Bankers, politicians,, actors, scientists (Bohr, Noether,, Feynman, Susskind, Newton, Einstein and many others) all of them aim to dominate humanity!

[@jameshall1300]

​@@johnnym6700 oh god, the king of word salad

[@iLLadelph267]

same here! had no idea there exist other universal speed limits below c

[@robertl4522]

I'll petiton my local council to raise the speed limit. You can thank me now.

[@auriuman78]

I'll sign but I think we'll need some good good luck 😅

[@nobodyinparticular968]

thank you

[@twixerclawford]

It's very rare that I come across a video talking about something I have literally never heard of before by any of the thousands of physics videos I've watched over the years. Excellent!

[@myyoutubeaccount4537]

Same.

[@tgr5588]

Legit question, if you’re watching physics videos for years then maybe it makes sense to go study physics at uni? These videos are nice, but they don’t really capture the picture of how a lot of things are derived

[@MiaWinter98]

@@tgr5588 If I would study any subject where I watch hundreds of videos about for years, i would have like 8 majors. People sometimes just like to learn things. (or have ADHD like me)

[@myyoutubeaccount4537]

@@tgr5588 Why do you suppose that watching thousands of physics videos implies no formation in physics? The GZK limit is not well known to physicists in general, it's a very niche phenomenon. I'm pretty sure most post-docs in physics don't know about it.

[@Ratzfourtyfour]

Why does this not have 1M views yet.

[@dialectphilosophy]

What a fun and interesting dip into relativistic particle physics! Great job making the video so accessible… we predict rapid channel growth heading your way!

[@lukasrafajpps]

Hi, thank you very much for such words I hope you're right :) I wish you all the best on your KZbin yourney guys :)

[@michelmeijer4509]

Thank you for building up such a topic with a historic reference frame. It makes the topic so much better to understand and to enjoy. Also, switching between you talking and animations was well balanced, adding to the lecture. I'd like more of this!

[@fubu666]

Imagine being a proton traveling at 0.99..9998c and watching photons travelling past you at c :)

[@lillyanneserrelio2187]

I want to but i can't because I'm using all my concentration to maintain my speed of 0.999c (yeah ONLY 3 9s. I'm 1 of the "slow" kids)

[@lukasrafajpps]

😁😁😁

[@caleroby9483]

The Naughty frames of reference.

[@marcuswar2823]

Not only that, but those protons would "see" light going a 1c FASTER than them. Lots of people visualizing this think light might seem very slow for them. But they don't. And its one of the "craziest" things about our universe.

[@drsjamesserra]

It’s still weird that even from the ultra fast flying proton frame light would move with c.

[@fizik_amorim]

I have studied this effect in the uni a few years ago but totally forgot about it. Thank you for refreshing my memory hahaha. Nice video :)

[@TazPessle]

New sub here. I love the pace, gives me enough time to actually understand what's being said before you move on.

[@GottaMineGottaCraft]

Ohhhh, subscribed! Walking through the math is incredibly useful. "There's a frame of reference where the CMB is stationary" is a concept I've never considered, thanks for blowing my mind like that

[@orbitalvagabond7371]

The mis-teaching of relativity has obscured that fact, sadly. A related concept is the "comoving coordinates".

[@seanmcdonough8815]

I love the accent! Rodiation! And Aye-ons! Just subscribed!

[@pluto9000]

It isn't a limit like the speed of light. It just explaining why we don't detect any protons going faster than that. If a high-energy cosmic ray doesn't interact with a photon from the cosmic microwave background, it would continue traveling through space without losing energy through pair production. This could allow it to maintain its high energy and potentially travel long distances across the universe.

[@realityisenough]

You're misunderstanding everything on a very fundamental level

[@technikchaot]

​@@realityisenoughcould you please elaborate how you mean this. Because in my opinion his understanding is not wrong on a "fundamental" level. Yes there are inaccuracies but nothing I would describe fundamental.

[@andredelacerdasantos4439]

Why don't you try accelerating while radiation of a temperature of about 8.8 x 10^13 K is slowing you down before you come here with your criticism, mister?

[@joda7697]

@@realityisenough They're really not. That cross sectional calculation gives you the average time it takes for an interaction with the CMB to happen. It in no way guarantees that it does happen anywhere near that time frame, or at all. Yes, for most particles, this will be fairly close, but some particles can just plain get lucky.

[@kobayashimaru8114]

@@realityisenough I think you've got that the wrong way round. Even the video itself stated that protons would have no upper bound to their velocity if it weren't for CMB interactions.

[@rtg_onefourtwoeightfiveseven]

Great video, everything was well-explained with just the right amount of detail. Subscribed.

[@lukasrafajpps]

Thanks for the sub!

[@bustacap503]

Wonderful vid, excellent visualizations, you rock!!

[@kyzercube]

This is one of those things that is staring you right in the face the whole time and is so simple, but it just never dawned on you ( at least that's how it is in my own point of view 🤣). Very informative and simplistic video!

[@thetinkerist]

I've not heard this explanation yet. Thanks! very interesting.

[@onehitpick9758]

The CMB shows us that we are moving relative to some frame, because we see a clear dipole, and also a quadrupole moment in the observed temperature. The postulate of relativity does not hold for our local, real universe because we are not in an absolute vacuum. If you try to travel close to "c" relative to your starting frame, the CMB will increase in energy to the point where it will eventually turn you into plasma.

[@lukasrafajpps]

true :) CMB slightly breaks the principle of relativity.

[@samscott6880]

@@lukasrafajpps How? The CMB is light.

[@bryandraughn9830]

​@@samscott6880 I think it would blue shift into the X-ray energy and higher. Light can carry tremendous amounts of momentum.

[@nosuchthing8]

This needs to be incorporated into science fiction novels.

[@thedave1771]

@@samscott6880the CMB creates a preferred reference frame which relativity says does not exist. It’s not really a conflict, since the CMB is light acting within the universe, but it’s potentially useful nonetheless.

[@dankuchar6821]

Excellent content! Please keep it up.

[@ghostofrecon1]

So all we need to see if a proton can hit the broad side of .1 millibarn

[@HA7DN]

My first idea was "it'll decay into multiple particles". It seems like my toughts were not that wrong, but I also learned quite a few new things.

[@Fixundfertig1]

Thank you for this new video ❤

[@rubetz528]

A very interesting effect, and a surprisingly simple one. Thanks for the video, I actually learned something new today.

[@johnburke568]

Greatly enjoy your content

[@user-wo6qn3vf9n]

Yes, it's because of the new Welsh speed limit.

[@hg6996]

This is a heck of an interesting video! 👍

[@darrennew8211]

What a fascinating combination of effects.

[@howtoappearincompletely9739]

That was very interesting. I'd never heard of Δ resonances before. Thank you.

[@donpeat7707]

Excellent, and good to see some numbers around interactions with a hotter CMB in the direction of travel for very fast particles. Thanks!

[@paulpease8254]

So interesting, thank you.

[@cavemanooga]

From one physicist to another, this was a great video!

[@ruperterskin2117]

Cool. Thanks for sharing.

[@pallharaldsson9015]

Good video though the number slightly wrong in the beginning, i.e incorrectly rounded, rather truncated, see it more accurate at <a href="#" class="seekto" data-time="601">10:01</a> then there also 21 nines then ending in 866.

[@sheshankutty8552]

In a lot of Physics related videos, I have not found lots of people talk about Cosmic Background Radiation but you did. It is an important piece in the mystery of cosmos in my opinion.

[@jareksprysz]

Thanks, man. That was interesting.

[@mrnice4434]

<a href="#" class="seekto" data-time="735">12:15</a> relativity is crazy Mr. Proton is going of for the weekend trip and Mrs. Proton staying at home has to wait 25 million years for him :(

[@daliasprints9798]

Real world Hoshi no Koe.

[@LowellBoggs]

great video thanks!

[@lucascsrs2581]

Amazing video, amazing explanation, amazing storytelling (and amazing accent hahaha). +1 sub

[@lukasrafajpps]

thank you :)

[@hens_ledan]

This is a truly great video - one the best physics videos ever. It raises the question: What else might the CMB affect? How might it affect neutrino flavour switching? Does genuinely new physics emerge at the interface between c and the CMB reference frame?

[@jensphiliphohmann1876]

Thank you for this interesting information.

[@samorostcz]

Nice one. Thank you.

[@johnt.inscrutable1545]

I enjoyed this video very much. I found you to be very well spoken and engaging. I hope you have great success with your channel and your Ph.D. studies. Thank you. InscrutableJohn

[@lukasrafajpps]

Thanks :)

[@marcelma]

Very interesting subject - and well presented! Still, you offered enough to get my mouth watery, but not enough to develop a satisfactory understanding. I'd like to hear a little more detail about the interaction between the proton and the microwave background.

[@lukasrafajpps]

I was thinking to write a short pdf script to every video with a bit more math so that viewers interested more into the topic could download and read but I didn't manage to find time yet.

[@auriuman78]

That'd be awesome 😎 I get it though, that's another hour or two even if you speech to text the transcript and just insert your math addendums at the places indicated. At least if you're a format perfectionist like me anyway 😉

[@davecorry7723]

Ooo, what a nice video!

[@user-ml4wm7ut5t]

I don't know what's more entertaining, the content or his accent. I like how he pronounces stuff.

[@lukasrafajpps]

:D there are divided opinions on my accent so thank you :)

[@user-ml4wm7ut5t]

@lukasrafajpps it is very strong, the accent, but that is your appeal, to me.

[@thedave1771]

@@lukasrafajpps whatever it’s worth, you’re completely understandable, and by the end of 2-3 videos I don’t notice it at all. Maybe that’s just me.

[@Liatlordofthedungeon]

Exellent work!

[@brockobama257]

This is the first time in a long time I learned something new about physics. I haven't been seeking out more knowledge how I used to and this makes me nostalgic.

[@jaybingham3711]

Cool info. Thx much.

[@dougieh9676]

Very interesting. Thank you for giving me a new obsession. Now I need to watch this every night for months. And the dreams too are going to be great. 😊😊😊

[@zachreyhelmberger894]

Fascinating!

[@deant6361]

Thanks for sharing.

[@grezamisoit]

Insane! Thx

[@eprohoda]

awesome ~💫

[@RVH-io3dr]

I didn't understand most of this (I only have high school physics), but I do enjoy trying to understand this speed of light limitation. So far this is the best video to explain the why of this limit. I will be watching this again and again until I 'get it'. Thanks! Subcribed.

[@lukasrafajpps]

Hi, it is nice to hear you are interested in physics :) The fact that there is a fundamental speed limit (the speed of light) is just observed fact and nobody knows why the speed limit is exactly the number it is. It is just the way the nature is and we have no clue why. This video is talking about the fact that protons have even lower speed limit than the speed of light.

[@Guido_XL]

@@lukasrafajpps Indeed. But, it is also intuitive to accept that particles with mass cannot infinitesimally approach the speed of light, as it would practically equal the speed of light then, therefore occupying all of the available energy in the Universe. The explanation as to what that limit really determines, may then be quite revealing to a non-physicist.

[@Guido_XL]

It is encouraging to notice that people without a university or college background in natural sciences are interested in such topics at all. Please keep this attitude up and remain interested! I hope this enthusiasm will irradiate towards others and induce some spark of enthusiasm as well. There is so much noise in this present-day world that distracts our attention away from what is really defining our world and our knowledge, that videos like this are a relief in that sense.

[@OrdenJust]

For best results in building an electroscope, use gold leaf for the hanging flaps. Gold leaf is beaten to an extreme thinness, and hence weighs less, and hence moves more for a given charge, and hence its displacement is more visible. Ordinary aluminum foil can be used instead of gold leaf, but the flaps must be very narrow to see anything.

[@b.griffin317]

Will this number change as the CMB cools? What you're saying seems to imply this. Or am I misunderstanding?

[@thedave1771]

Literally my first thought, so I popped into the comments. I haven’t seen it discussed anywhere here.

[@nothingbutlove4886]

Homework for you: pause at 10:03 and think about what would happen to small beta, if you only lowered the value of the cmb radiation in the formula.

[@orbitalvagabond7371]

Very nice video, both a lot of detail and easy explanations. Relativity declares that no rest frame has special rules of physics. But it's been mis-taught as "there is no universal rest frame," when for many purposes the CMB fits the bill. This also answers my anxiety-inducing thought experiment of "what's stopping near-light speed objects from coming from deep space and just absolutely annihilating us?" This at least puts a rough upper bound to what's possible.

[@nickrobertson2450]

Fascinating. I don't recall learning any of this story during my physics degree in the mid 1990s.

[@theunlearnedmind7374]

This blew my mind.

[@xuko6792]

"Incorrect measurement" - top choice energy provider!

[@JTheoryScience]

you explain this lovely, i hope to hear more from you in the future. Collab with Anton Petrov perhaps?

[@ChaineYTXF]

that was superb!👍👍

[@lukasrafajpps]

Thanks a lot!

[@PlasmaFuzer]

For people that can't contextualize how insane 50 J of energy from a single proton really is, here is a little example: A single proton is a hydrogen nuclei. At STP, one mole of hydrogen gas is ~87% of a cubic foot. For my purposes, you could hold the container in your hands easily. There are Avogadro's number hydrogen atoms (pretending their just nuclei is sufficient) ~ 6 *10^23 Thus if this mole of gas was accelerated to the same energy as the single proton, there would be 30*10^24 = 3*10^25 Joules A quick google search shows (approximately) 4.2 *10^9 J = 1 ton of TNT, So, ~3/4 or: 0.75*10^(25-9) = 0.75*10^16 = 7.5*10^15 tons of TNT That's 7.5 MILLION BILLION TONS OF TNT. A billion megaton nukes, a million gigaton nukes, etc. I believe that is more energy than all of human activity in our entire history has created, or something close to it. Absolutely insane.

[@dariuszg.8026]

english isnt my native launguage, but your explenations are so great that I can understand it with my avarage level on english ;D

[@davidgifford8112]

“OMG particle” how cool is that!

[@markzambelli]

Thankyou for this vid... before watching I had naively assumed that this upper speed limit might be due to the increase in relativistic mass pushing the proton mass up so high it would become a blackhole but now I see that I'm probably orders of magnitude off when this would (could?) happen. Thanks again.

[@OzGoober]

Thank you, this is an awesome video. From simple examples to real numbers in maths. <a href="#" class="seekto" data-time="249">4:09</a> Aliens! (it's never aliens) <a href="#" class="seekto" data-time="510">8:30</a> "photon on it's own..." proton, it happens. <a href="#" class="seekto" data-time="644">10:44</a> Cool, I've never heard of that unit of measure!

[@Gaswafers]

I thought for sure this was going to be something like "beyond this speed, it has so much energy that it turns into a blackhole".

[@technikchaot]

This energy is some orders of magnitude bigger to turn something of the radius of a proton into a black hole. But this would be a fast moving black hole and this would mean it has very different gravitational effects on its surroundings than a stationary or not relativistic fast black hole. So no one really knows exactly how this would work out.

[@larrywarkentin6060]

In your final calculation, where you find 'days' for the interaction, you appear to calculate gamma using (v/c) rather than (v/c)^2. Using the correct calculation should yield an interaction in 'moments' rather than 'days' (in the proton's timeframe). Otherwise, good perspective!

[@crp2035]

Excellent presentation on this curious subject. One comment: 50 J is below the low end of bullet energies (~150 J) and much lower than standard ones (>1000 J). Not recommending a 50 J bullet to anyone, but, still. Cheers!

[@praveenb9048]

It's in the airgun range. In many countries you need a licence for air guns over 7 Joules.

[@wernerviehhauser94]

It's in the .22LR energy range.

[@DrDeuteron]

@@praveenb9048 -countries- *tyrannies

[@dot1298]

@@DrDeuteron soo.. you find it tyrannical, when the police has the monopoly for weapons, causing much less gun violence in that country?

[@dot1298]

example: Japan.

[@TubeYou31415]

Great video as always! I was very surprised that the limit had to do with the CMBR interaction. My first guess was that there would be a speed limit for protons when their total energy was large enough to create a black hole. As far as the limit you present, I don't think it's universal. In principle, couldn't one build a large Faraday shield which would prevent the proton from interacting with the CMBR? I'm guessing the calculation of the kinetic energy of a proton needed to collapse into a black hole is not too difficult.

[@Berend-ov8of]

It is somewhat counter intuitive to consider that going very fast could mean coming to rest for anything. But that's how it is for everything that has a constant speed.

[@johnmckown1267]

Excellent. Never heard of this before, but you explained it so well, even my average brain got a decent understanding.

[@lukasrafajpps]

Thanks for the kind words and the support. Much appreciated :)

[@googleyoutubechannel8554]

So it's relatively simple to shield from the CMB, is this limit more just a practical effect?

[@digitalatom6433]

So the most remarkable thing I learned is that if you travel near the speed of light, then relativity makes it so that the journey doesn't take as long from your perspective as it does for the people you left behind. You could travel the stars in just a few days... at least, so you'd experience, when actually millions of years have passed.

[@KeviPegoraro]

Can we go faster in a particle accelerator? Or the ones in the wave front of a supernova?

[@DSAK55]

Excellent

[@saveearth9816]

Continue.... Your channel is very good... Soon you will be famous U. tuber

[@randalljsilva]

Thanks!

[@lukasrafajpps]

I thank you for the support :)

[@merion297]

Wow, mindblown! 😊

[@tinfoilhomer909]

For a foreigner your English is really good. Understood every word.

[@dankdungeon5104]

it's mid

[@lukasrafajpps]

thanks :)

[@gregmarsters2434]

You mentioned heavier nuclei. Is there some reason they don't think it was, say, iron or bigger? If it was anti-matter would that change the readings?

[@pauldietz1325]

Heavy nuclei would have a lower speed limit, due to photodisintegration from blue shifted photons.

[@douglasperry8211]

Something new? Awesome!

[@axle.student]

Thanks, I am enjoying your content :) > Some part of me always questions if a photon is truly traveling at the "limit", or if the photon is just the most obvious observable for us and other unseen "stuff" can travel faster. (Keeping in mind, when we start talking about n decimal degrees of precision, that the speed of a photon is just a low precession estimate to begin with)

[@ryanwitt3480]

Great video! I assumed you would talk about the cmb photons eventually turning into black holes due to the blueshift relative to the photon. I am not a particle physicist, so ill just ask if this is possible too??

[@kapsi]

Not a physicist either but I don't think so, you can't have something be a black hole in one frame and not be a black hole in another frame

[@lukasrafajpps]

This can't happen it would broke the principle of relativity although iteresting to think about it.

[@henryptung]

I'm not sure the "photons turn into black holes at the Planck energy" argument is really about turning photons into black holes, rather an illustration of the theoretical gap between particle physics and gravitation. We know the models break down at these distance/energy scales, we just don't know how to fix it yet. But no, these blueshifts aren't enough to reach the Planck energy. The blueshifted photon energy here is ~10^8 eV, whereas the Planck energy is ~10^28 eV - we're a bit short.

[@kylelochlann5053]

No, not possible for a photon to become a black hole.

[@pwinsider007]

​@@lukasrafajppsDialect said that internal pressure of earth accelerates every part of earth outwards and spacetime falls inwards to rescue all parts of earth and this is real cause of gravity and he also said that all other scitubers are giving wrong explanation of gravity by saying time dilation is cause of gravity.Please make a reply video on it and tell true cause of gravity ,dialect disproved that time dilation is cause of gravity but his explanation is also wrong because gravity cause internal pressure of earth and internal pressure of earth doesn't cause gravity.

[@OJapaTerrorista]

Did a quick research on how far is 25.7M ly, and aparently there's plenty of galaxies within that range, Andromeda is about 10 times closer than that. So it's possible that those OMG particles were formed quite close to us.

[@alexanderf8451]

The mystery is how something nearby could produce protons at such high energies without also being very easy to find by other means.

[@vladimirmihnev9702]

I have heard somewhere that at close to light speed all the light is blue shifted to gama rays. Also will that proton not also hit photons from other light sources, that have more energy to start with?

[@Risu0chan]

Particle physics on youtube? I hit the subscription button at (near) the speed of light!

[@simonwatson2399]

Does this mean that there should be excess protons at the lower energies? If so, is that detectable as a proof/signature?

[@Unmannedair]

"lower energies" 😅 yeah. And there should be a curve of energies related to distance from the source and time traveled. The CMB didn't used to be microwaves the whole time. At one point it would have been visible. That means less speed required to reach the same effect and thus the limit would have been lower at that time. So very very old protons that have been traveling longer should also be much lower in energy.

[@NicleT]

<a href="#" class="seekto" data-time="661">11:01</a> it's written "ly" so light years, a distance, but you say "years". Was this an intentional équivalence? Thank you for the great content!!

[@lukasrafajpps]

I wanted to say light years and I noticed this mistake when editing but since in this context it is kinda interchangeable I didn't bother to redo the whole thing just because of it.

[@KeviPegoraro]

also as the universe expands this limit increases, i wonder what is the formula f(% of C ) that returns the time we need to wait to be able to get a proton to that speed, and if a proton can go, a space ship can as well? or other stuff breacks before?

[@samwisegamgee4659]

*LIKE* Now, does this limit have implications for a proposed Large-LHC (100 km ring)? Or for that matter an ultra-large-LHC built in Outer Space, that I've heard some discussions of recently?

[@lukasrafajpps]

This limit is far beyond what humans could ever reach. The LHC operates at 7 TeV per proton which is 7*10^12. It is 7 orders of magnitude lower than the GZK limit. The 100km rigng is expected to reach 50 TeV which is still 6 orders of magnitude below. But, if we ever had such technology to build collider large enough we could cool it to the temperatures near absolute zero and therefore this effect would not be problem.

[@samwisegamgee4659]

@@lukasrafajpps Thanks for the knowledgeable answer. While the verification of the Higgs particle was fantastic it was a bit disappointing that other theorized solutions such as Supersymmetry were not seen at the energy levels generated by the LHC; now they want to request more Euros to build the 100 km ring. These numbers give me something to use a reference.

[@rykehuss3435]

I'm interested in knowing how you can have a reference frame where the CMB is stationary

[@lukasrafajpps]

It is the frame in which it is isotropic for example the Earth is traveling at around 370km/s relative to the CMB

[@rykehuss3435]

@@lukasrafajpps Maybe I'm having a difficult time wrapping my head around that concept. Wouldnt it imply that the CMB originated from some point in the universe? or that it has a direction at all

[@SachinSingh-pu1nc]

At <a href="#" class="seekto" data-time="601">10:01</a> you used c for value of beta which is not required as it is just a dimensionless ratio.

[@DrDeuteron]

luckily c=1.

[@lukasrafajpps]

Yes true, sometimes I lose focus on these things. Thanks for correcting.

[@christianlibertarian5488]

New concept for me. The CMB sets a standard frame of reference. That changes a lot.

[@kylelochlann5053]

Anything can be a standard reference frame, a particular flight from NY to London for example, is just that the CMB makes for a very convenient frame.

[@General12th]

*A* standard frame of reference, not *the* standard, since that doesn't exist under special relativity. But the CMB is nice and universal, so it's pretty convenient.

[@lancebradshaw4829]

It occurred to me recently that such highly energetic protons might be produced in the evaporation of primordial black holes. The Hawking radiation generated by a black hole becomes increasingly energetic as it becomes smaller. A black hole on the verge of vanishing completely should emit particles close to the order of magnitude of the Planck energy, which is well beyond the GZK limit. At least, if the math in regards to such evaporating black holes is correct.

[@brettski74]

What about other particles? For example, are there similar interactions between neutrons and the CMB that limit their speed as well?

[@lukasrafajpps]

Neutrons can't be accelerated towards such high speeds since they are neutral moreover they are unstable with a mean lifetime od couple of minutes. But taking this aside there is no direct interaction of neutron with photon since it is uncharged.

[@STONECOLDET944]

To put it simply using a very rudemtary metaphor , the intrinsic lag of the proton is barriered by the intrinsic frame rate of open space .

[@davidgreenwitch]

So then... I assume electrons have to be even slower then?

[@natel3250]

Am I understanding correctly that basically protons traveling through space meet resistance from the CMB which creates a speed limit of sorts?

[@DavidWitkowski]

Great video, but please explain a "barn"? Maybe I misunderstood the word.

[@lukasrafajpps]

It is a unit used in particle physics and its definition is literaly 10^-28 m^2. If you will you can think about it as a thickness of the particle, the more thick the more likely the interaction is gonna happen.