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Isn’t 90% of proton’s mass the result of binding properties of the strong nuclear force? Isn’t it thus possible that much of the universe’s mass/gravity is the result of similar interactions between constituent entities?
5:21 two things, 1 how do you get the photons into a sealed box and measure how many are there without affecting the number in there. 2 how do you measure if any are gone without affecting the number in there?
i guess in highly controlled enviroment you can calculate how much energy you have escaping thru the walls as heat and how much the detection reduces the result . Then you are just waiting if you have different results then what you calculated
@@pumpa244what if photons release heat upon turning into dark photons ? which shouldn't make sense anyway since they gain mass upon doing so ; regardless of the potential heat generation, where does this mass come from ?
What blew my mind was photons have no mass, but they do have momentum. I watched another video that explained it using only high school physics, good stuff.
The simple explanation would be that energy is a combination of mass-energy and momentum-energy. So if it doesn't have mass, all it's energy is in momentum.
As far as i understand it, the dude in the video was sort of wrong on this because mass and energy are actually the exact same thing. To my understanding from other's explanation photons themselves are massless and therefore they have no energy, however them simply moving through space creates energy/mass. So the dark photons would have actual mass, so it's not all just momentum.
@@stevenfallinge7149I wouldn't put it like that. Rather, there's a thing called four-momentum. Energy is its time component, momentum is its space component, and mass is its norm (component = coordinate, norm = length). For photons, when calculating mass, the components cancel each other out by the rules of the Minkowski geometry (which is the geometry of spacetime*) *According to GRT, the geometry of spacetime is actually a generalised version of the Minkowski geometry
@@loganwolv3393As I understand it, energy and mass are not exactly the same. There's a value called four-momentum. Its space component is the momentum, its time component is the energy, and its norm is the mass (component = coordinate, norm = length). So, mass can be calculated from energy and momentum
@@maltheopia and you unlock this door with the key of imagination. Beyond it is another dimension - a dimension of sound, a dimension of sight, a dimension of mind.
I do research with the LDMX and HPS; two US based experiments aimed at covering a large swathe of the parameter space for the Heavy Dark Photon. This was a nice video :).
It would be nice to know what speeds these dark photons travel at. If they have mass, they cannot travel at the speed of light, so what is their velocity?
I would assume they travel about as fast as you can with mass, like however fast beta radiation travels. Or as fast as photons move, since they still act like they have some mass and don't actually make it to the universal speed limit (or at least not past it)
I still find it contradictory that regular photons have zero mass. If their mass is flat out zero, while their energy is calculated by squaring some mass then surely the mass isn't 0 to begin with or there's nothing to square and thus no energy. I'm sure I'm just too poor to truly comprehend what it is all about. I've heard Arvin Ash and Anton Petrov and Sabine Hossenfelder occasionally say "if photons have mass then it's incredibly tiny", but **how** tiny? It being zero is important in so many formulas that we just cannot guesstimate or round this off or else galactic scale calculations would not match observations.
@@Yezpahr it's pretty common for people to use E=mc^2 which isn't the full equation. The full equation is energy squared equals its mass times the speed of light squared all squared PLUS its momentum times the speed of light all squared. E^2=(mc^2)^2+(pc)^2. E=mc^2 refers to "rest mass" and is used in nuclear binding equations. Light on the other hand doesn't have a rest mass so its energy comes from its momentum times the speed of light.
Thank you for reverting back to the old way of advertising the sponsor of the video. Inserting the ad somewhere halfway through the video was a very frustrating listening experience.
What do you suggest? It's really because it's the only option left that can fit with our observations without completely upending the SM. If it were strong or em forces we'd probably have detected it by now and observations also suggests it's more than gravity. Anyways see WIMPs to read more about it.
@@geekjokes8458 To be clear, dark matter might not interact weakly, but that implies the SM could be in dire need of a replacement, and given it's success that's not something to consider lightly. We call it dark stuff because we haven't detected it directly, but instead it's a correction that we need to exist to explain our observations of the universe with SM+GR. Either it's very massive or there is much more of it than ordinary matter. Either way, if it was strongly interacting, then we wouldn't only be seeing it in gravitational effects so late in the game to need to correct for it. Given gravity is so weak, the strong and em forces that would be appropriate to consider would drown out normal matter interactions and we wouldn't be sitting here questioning about the existence of a seemingly not-fundamentally-interacting thing. WIMPs follow the chain of thought: there might be a mechanism causing dark matter to be more massive than ordinary matter, then to keep dark matter consistent with our observations, it could only possibly be interacting so weakly we haven't detected it despite its abundant gravitational influence. If they were massive particles interacting via strong/em, their force interactions would be enormous and be hard to miss in a particle accelerator or during chemical synthesis. If they were not massive, there would have to be so many more of them the lack of such events is inexplicable - unless interactions are weak enough to elude our experiments.
“But that hasn’t stopped theoretical particle physicists. Because when they say that dark matter only interacts gravitationally, they don’t really mean it. Instead, most assume that every once in a while, a dark matter particle will smack into a regular particle and interact via the weak nuclear force.” I really wish people would explain the motivations behind such an assumption instead of just taking it for granted. Why do they assume that? What observations or experiments or even just philosophical reasoning supports that idea? Nobody ever says.
I find it absolutely hilarious that in astrophysics that everything in the past two decades are named after stuff that you expect to see in a Marvel comic book or a Transformers cartoon show. 🤣
Similarly, SpaceX rocket designs have a retro Sci-Fi look resulting in SpaceX launch videos weirdly looking less realistic than Hollywood special effects.
4:05 Yes, but thats not at all how it works though?? Gravity has nothing to do with mass beyond mass being equivalent to an amount of energy. All photons have gravity.
Almost sounds like Dark photons are a polarization(?) of regular photons in the electric field, much like how the different flavors of neutrinos change identity depending on their distance from the source. Interesting!
2:10 I'm intrigued by this. Have there really been trillions of experiments with particle physics? I suppose it's possible, but that just seems orders of magnitude beyond what makes sense as a possibility.
Avagadro's constant really helps here, a trillion is only 10^12, one mole of material is 10^23. The LHC operates on beams of 2.8 x10 ^ 14 protons, so every particle experiment can easily net billions to trillions of collisions.
It depends a bit on how you define an 'experiment'; as a project or as a single test. The LHC for example is one single project, but conducts many individual tests each day.
@@jameskinardSure, but each collision isn't a separate experiment. That's not how laypeople *or* scientists use the word "experiment" - that's not even consistent with the way the video uses the term elsewhere within its script. I can't reasonably say I'm conducting quadrillions of experiments in genetics by counting every base pair that's part of transcription, translation, repair, and replication in my body. It was a silly thing for a science video to say and totally unnecessary to the point.
I got to thinking about this problem deeply and found it odd that spacetime curvature is the only thing that doesn't collapse the wave-function of photons and I'm sure that spacetime it self is the missing mass/energy in the universe. What I'm getting at is that spacetime seems to happen faster than c (it's the constant of constants hence no wavefuction collapse).
I always wanted to know if one can really trap light. The issue is that once you open the trap, the light escapes waaaaaay too fast to see if it ever stayed inside. I guess they are trying to use that idea to see if light will ever convert into something else to escape a trap meant for light-light
Energy will escape as heat pretty rapidly. My only guess here is that they would be trying to measure the rate as with that escape happens and see if it appears to be even faster than expected. Just guessing here.
well heres the other problem even if it did stay in it would well stay in meaning couldn't see it although there is a way to know if you trapped some light as the container would get heaveir as mass is just energy thats localized
It has "theoretical mass" and, therefore, is affected by gravity. It's like how when you're turning in a car and it feels like you're being pulled in one direction, but it's just the inertia of your body. That's how light is affected by gravity. The photons ride on the curvature of spacetime like a car on a banked, curved road.
Hum. Most say that gravity isn't really a force. Also E=mc² is just the part for particles with mass, the more complete equation is E² = (mc²)² + (pc)² And for massless photons, it is the (pc)² part that is non zero. Where p is the momentum. But yes, photons do in some ways behave like particles with mass, precisely because they do have momentum.
I like the idea of photons as the "representatives of the electromagnetic force". Like they're the diplomats that interact with reps of the other forces, and matter.
If energy can act like mass in certain situations then is it possible that dark matter could be explained by interactions of highly charged energy creating a sort of virtual mass which would produce gravitational effects?
Light does this as it gravitationally lenses, but it also loses energy to the vacuum as it red shifts adding a bit to the expansion of the universe. I'm wondering if this dark light-like particle could be in large enough quantities, but with lown enough energy to be the culprit behind both dark energy and dark matter.
@4:05 photons and all mass-less forces/electromagnetism have zero mass hence why they all move at c (the speed of light). Seems like our detectors are not tuned to detect something faster than c or spacetime wakes. Spacetime it self seems to be black and mass-less and we have a hard time measuring it's curvature and speed/time-dilation without reference points and local sensors (think The Great Attractor for example). Another way I like to think about the spacetime wake/blueprint is time travel, if I just traveled back in time but not space I wouldn't end up on Earth (ever), I would also need to follow Earth's path back in spacetime making the distance long in space and time, this lead me to imagine a wake from where Earth has past back in time. The problem is that the Earth is moving in a very complex path through spacetime (corkscrew around the sun, that corkscrews around the milky-way, which is colliding with another galaxy while the great attractor curves it all)
@2:30 but gravity is not a force, it's just spacetime curvature. People are thinking about this missing/invisible mass/energy all wrong, for all we know it could just be spacetime wake's we cant see bending light (it takes energy/mass to curve spacetime) so it's reasonable to image spacetime wakes like a worn horse track. The effects of mass/energy after a solar system or galaxy moves on from that spacetime frame would logically leave a ripple/wake/fingerprint behind. Also the law of conservation of energy basically imply's that something has to happen to the energy invested to curve spacetime...
If there's some kind of cycling between states like there is with neutrinos, there might be some kind of other conceptual experiments to test the idea. Seems like you could map out concentric rings from all known radiating photon sources, with the ring spacing based upon the frequency of the predicted switch between phases. With various photon sources in a region of space, those plotted rings would produce all kinds of interference patterns with nodes and anti-nodes. So the interesting effects should be predicted to occur where nodes bunch up. Not sure how well a model would match a prediction, but I suppose that would be interesting to test out.
There is quark mixing. More recently, we discovered neutrino mixing. So now, someone has come up with a hypothesis of photon and dark-photon mixing. It would be nice to see what comes of that.
3:33 Let's see... Dark photons have a small amount of mass, may interact via the weak force, and interact with gravity as well. This is all described by Neutrinos. More discussion needs to be had about Neutrinos as a possible solution to "dark matter".
Yes, I had the exact same thought. I'm assuming scientists have ruled them out because we have estimates of how many there are, and they just don't account for enough mass?
That's sterile neutrinos, the regular kind being too light to behave like dark matter. That's far from a dead supposition, though generally neutrinos and photons aren't interchangeable.
@garethdean6382 I'm a skeptic of "dark matter". I was suggesting that rather than inventing a new possible explanation for dark matter (this dark neutrino), scientists should go back to investigating neutrinos roles in the observation that led to theorizing "dark matter". Hope this better explains my original comment.
@erinm9445 I'm doubtful we have good estimates on the number of neutrinos in the universe (both normal and sterile neutrinos). IMO, it seems that a lot of energy is being wasted (pun intended) on finding dark matter when we already have a good candidate. I hope this better explains my thoughts.
Obviously any photon in the cavity will be absorbed in a very short amount of time by human scales. But careful tuning of the reflectors and cavity shape will maximize the power in the cavity, and increase the expected rate of normal to dark conversion. The paper also discusses the risk of normal photons escaping and reaching the detectors, and how to prevent that.
I'm making a prediction there's a 'dark quantum field' out there. What the heck! They haven't experimentally observed dark matter, dark energy, or dark photons?
Hi Reid! We should point out that light has no mass, no really, not even in that sense! E = mc^2 doesn't apply to photons since they have no rest energy. For them, the full equation simplifies to E = pc. And in general, gravity doesn't act on rest mass, it acts on _total energy,_ of which rest mass is one component.
It acts on total energy of a system, which is equivalent to the rest mass of that system. Gravity doesn't act on the kinetic energy of an object in motion, because that energy is relative and gravity is not.
@@erinm9445 Total energy depends on relative velocity. It's one way to look at the reason why you can't keep pushing on an object to accelerate to the speed of light -- its inertia (the Pythagorean sum of rest energy and kinetic energy) goes up the faster it moves from your perspective.
@@General12th Yes, total energy *of the system*. A system contains objects that have momentum relative to each other. All of that internal momentum contributes to that system's rest mass. But if you want to talk about the gravitational mass of a single object within that system, you still only look at its rest mass. That object is, after all, at rest from its own frame. When you ask how much kinetic energy an object has, you have to ask, relative to what? But when you ask how much gravitational acceleration something produces, you don't ask "relative to what?" that wouldn't make sense. So when you look at the gravitation caused by the earth, you don't include the kinetic energy of the earth relative to the sun or the planets (or relative to the Milky Way or the CMB), you only look at its invariant mass. But when you look at the gravitation caused by the solar system, then you include the contribution from the invariant mass of the earth plus the momentum of the earth relative to the sun and planets.
The explanation at @4:00 is slightly misleading, implying you only have gravity when you have mass. However, a normal photon should also be a source of a gravitational field, due to its energy-momentum, even though it has no inertial mass. Perhaps the key point is that a "dark" photon would have a much _larger_ gravitational field due to that small (but non-zero) mass converting to a proportionately much larger energy (compared to its "light" photon counterpart) due to the c-squared factor?
I have heard a million different times that the Standard Model and General Relativity don’t work together, but why? Like is it a problem of them making different predictions that are mutually exclusive? What is incompatible about them?
Oh, dark matter, the cosmic clown that's had astronomers chuckling for a century, and there's still no sign of a punchline that makes sense. It's like they've been on an intergalactic wild goose chase for a hundred years, and all they've got to show for it is a bunch of cosmic whoopee cushions that keep deflating when they sit on them. Now, enter axions, the absurdity's absurdity. Astronomers, in their never-ending quest to turn the universe into a comedy show, have introduced these quirky particles into the cosmic script. It's as if they've decided to juggle flaming bowling pins while riding a unicycle on a tightrope that's on fire - you know, just to make the whole thing even more ridiculous. Picture this: Astronomers, with telescopes pointed at the void, staring blankly at the cosmic canvas, suddenly shout, "Dark matter, axions, and...um, other stuff, I guess?" as if they're naming random things from their grocery list and hoping it will magically make sense. It's like trying to play chess with a set of Scrabble tiles - chaotic and utterly incoherent. They've essentially turned the pursuit of knowledge into a century-long cosmic slapstick routine, where the punchline is eternally delayed, and dark matter is the banana peel that keeps astronomers slipping. Axions, in this carnival of chaos, are the cotton candy that's been flung into the crowd, sticking to everyone and making everything even stickier. So, here's to our persistent astronomers, who've transformed the cosmos into a never-ending cosmic stand-up show, with dark matter as the bumbling, pratfall-prone comedian. Keep the popcorn handy, folks; this spectacle of cosmic confusion shows no sign of a sensible ending anytime soon.
We see the “surface” of “dark matter” indirectly through the tug of the universal fabric of spacetime upon our visible galaxies. However, the interaction of “dark matter” otherwise is performed BELOW the surface of spacetime within the interstitial boundaries of “as above, so below”. 😊 4:28
How do we know that parts of things we think we fully understand aren’t influenced by dark matter or dark photons? Like radioactive decay… maybe dark something being everywhere all the time is partially responsible for the consistent decay we see in the elements.
It is getting more and more bizarre. Like observing the galaxies rotating like LP, outer arms not slower... Everything else we observe on a smaller scale shows a lag in the outer edge if not forming one solid mass altogether. Or is it because there is not much medium like we have air on Earth that slows the rotation further from the center and that galaxies are usually so far from each other that even their mutual gravity is too weak?
Could the light photon ∆E=hf form the characteristics of time with the exchange-quantized energy continuously converting potential energy into kinetic Eₖ=½mv² energy of matter in the form of electrons forming our ever-changing temporal world?
About the light through wall experiment, isn’t matter mostly empty space meaning that some photons will escape regardless of if it turns into dark photons or not? Please correct me if I’m wrong.
I think I saw this TV show, the one with the androids, the serpents, and the dodecahedra. Makes me wonder if Neutrinos changing type is related. Or what if the Standard Model is just one corner of a multitude of standard models all active in the same volume but rarely interacting, like subspace or alternate dimensions in fiction.
Btw to explain why light doesnt have mass even if E=mc2 if youre confused its that that is the version for an object without motion in a point of view, but the whole thing of relativity is also that photons are always in motions no matter the point of view, so they follow a more complete version E2=m2c4+p(momentum)2c2 so the energy light is not mass, but does mean it can transfer momentum, as seen in solar sails
Oh its an idea for space propulsion that a lot of people talk about basically, have an object in space deploy a huge surface, and use the momentum from the light of the sun hitting into to propel the craft and it will slowly build up speeds@iro4201
I love how the Light-Shining-Through-Wall experiment once again confirms my bias that researchers have zero talent for naming things. This isn't why I didn't become a researcher, but I'll pretend it is, just because it feels like a moral imperative.
I have often thought about wavelength of photons being stretched as they traverse the vast distances of intergalactic space. It does not seem impossible for the wavelength to become so long that the wave function describing the energy is so dispersed in space to be inert with anything else locally present. It is not inconceivable to me that the energy traversing through space may be so stretched out as to be undetected by us in any other way than through the vast bulk observations at galactic and intergalactic scales. The universe is likely filled with these very long photons that we have no hope of ever detecting. I am thinking here about photons with a wavelength on the order of light years in span.
Given that light loses energy to red-shift into the expansion of the universe and that massless particles can still effect gravity with their momentum, what if there where just an extremely large number of light like particles losing energy to the vacuum and causing gravitational effects, but in a mostly non-interacting field? Each particle would be too low energy to detect by itself, but it could potentially be creating what we see as both dark energy and dark matter. This is purely unresearched conjecture on my part.
"if the amount of light vanishes from the box, that means some of it must have transformed into something that can tunnel through walls" but isn't quantum tunneling already supposed to be a thing with pretty much any matter? theoretically? at subatomic levels etc? so if that happens, it doesn't necessarily mean the light transformed, it might mean some light just quantum tunneled out.
Yes, however tunneling depends on distance. Two hydrogen nuclei need to be VERY close to have a small chance of tunneling,but the water in your body isn't undergoing fusion. A thick enough wall will easily reduce the chance of tunneling down to the likelihood of the boxes atoms suddenly fusing into gold.
Why do we assume spacetime is flat to begin with? If it wasn't, then large masses like black holes and galaxies would tend to settle into the dips. This would explain why they would form so soon after the BB and also why they rotate faster than their own mass would suggest they should. This would also explain the accelerated expansion of the Universe. Spacetime is far from flat! And we don't need any internal reason for that to happen.
4:35 If a dark photon had mass, it wouldn't be a photon. If a photon turned into a dark photon, it would have to gain mass and would no longer travel at the speed of light. Photons like all other force carriers including the theorized graviton, are massless. If I know this, physicists know this. So I don't understand the hypothesis. 5:18 - "light shining through wall" (old news from 2013) and NA64 have found no evidence of the interactions after a literal hundred billion particle collisions. It is easy to understand why. At least we've made progress proving it doesn't exist.
Right now, LMNT is offering SciShow viewers a free sample pack with any order. That’s 8 single serving packets free with any LMNT order. It’s a great way to try all 8 flavors or share with a friend! Get yours at DrinkLMNT.com/SciShow.
Isn’t 90% of proton’s mass the result of binding properties of the strong nuclear force?
Isn’t it thus possible that much of the universe’s mass/gravity is the result of similar interactions between constituent entities?
@@tropickmanyes
The light-through-the-wall experiment is genuinely a random question I've had in my mind for a lot of years. I look forward to seeing its results.
You might not be able to *see* that light, though...
@@DunnickFayurolmao
Well how about reading about the results then
Same, we all have thought about it
lol yeah, the problem is mirrors dont reflect 100%, its like 95% so it gets dark quick, basically instant
This is bringing back flashes of my Waveguides class in college. *shivers*
5:21 two things, 1 how do you get the photons into a sealed box and measure how many are there without affecting the number in there. 2 how do you measure if any are gone without affecting the number in there?
3. There's no such thing as a perfect mirror and the photons will be converted to heat almost instantly.
i guess in highly controlled enviroment you can calculate how much energy you have escaping thru the walls as heat and how much the detection reduces the result . Then you are just waiting if you have different results then what you calculated
@@pumpa244what if photons release heat upon turning into dark photons ? which shouldn't make sense anyway since they gain mass upon doing so ; regardless of the potential heat generation, where does this mass come from ?
@@maxanimator9547 well then there would be more heat measured than it should be. But i dont really know this is way beyond science enthusiast level
This "experiment" is designed to produce a false positive.
What blew my mind was photons have no mass, but they do have momentum. I watched another video that explained it using only high school physics, good stuff.
The simple explanation would be that energy is a combination of mass-energy and momentum-energy. So if it doesn't have mass, all it's energy is in momentum.
As far as i understand it, the dude in the video was sort of wrong on this because mass and energy are actually the exact same thing. To my understanding from other's explanation photons themselves are massless and therefore they have no energy, however them simply moving through space creates energy/mass. So the dark photons would have actual mass, so it's not all just momentum.
@@stevenfallinge7149I wouldn't put it like that. Rather, there's a thing called four-momentum. Energy is its time component, momentum is its space component, and mass is its norm (component = coordinate, norm = length). For photons, when calculating mass, the components cancel each other out by the rules of the Minkowski geometry (which is the geometry of spacetime*)
*According to GRT, the geometry of spacetime is actually a generalised version of the Minkowski geometry
@@loganwolv3393As I understand it, energy and mass are not exactly the same. There's a value called four-momentum. Its space component is the momentum, its time component is the energy, and its norm is the mass (component = coordinate, norm = length). So, mass can be calculated from energy and momentum
6:45 "physicists aren't just going through a goth phase"
It's not a phase mom, this is the particle I really am!
With a pint of snakebite and black in one hand and a can of hairspray in the other the goths will take over the universe!!!
something something circular light polarization something something twisted phase.
Mom, call me Nycton
Oh goth, whoda thunk it?
Saying "Back in the 20th Century" suddenly makes me feel so old.
Yeah, that still catches me off guard.
90s kids are 30 year old adults now. I myself was born in the late 1900s.
i still miss the 80s though
They are using a mirrored box. That's what some paranormal investigators call a Demon Trap.
Good thing I am the demon cleaner.
Hmmm. Perhaps a... Maxwell Demon's Trap? And the mirrored walls are in fact... doors?
@@maltheopia and you unlock this door with the key of imagination. Beyond it is another dimension - a dimension of sound, a dimension of sight, a dimension of mind.
Success! Oh, no that's just filth on the mirrors. "Who covered the walls in sh..."
Dark light are actually demons and true light are angels.
-occult theologians 1
-scientists 0
I do research with the LDMX and HPS; two US based experiments aimed at covering a large swathe of the parameter space for the Heavy Dark Photon. This was a nice video :).
My dad is also a different kind of invisible
MiLKnvisible👀ツ
😂 sorry, had to dip! Yo mom is a different kind of ....... 😅 jkn
Im kinda invisible to my dad
Not to his other family
@@SynthRockVikingI didn't know John Cena had kids. I really didn't see that coming.
Been really happy to see more of Reid these past few videos
"Back in the 20th century" that hit me hard... dang it is a quarter century ago...
It would be nice to know what speeds these dark photons travel at. If they have mass, they cannot travel at the speed of light, so what is their velocity?
I would assume they travel about as fast as you can with mass, like however fast beta radiation travels. Or as fast as photons move, since they still act like they have some mass and don't actually make it to the universal speed limit (or at least not past it)
@@archerelmsstuff with mass can move very very fast like the omg particle or whatever that transmitted a pretty large amount of energy for its size
I still find it contradictory that regular photons have zero mass. If their mass is flat out zero, while their energy is calculated by squaring some mass then surely the mass isn't 0 to begin with or there's nothing to square and thus no energy. I'm sure I'm just too poor to truly comprehend what it is all about.
I've heard Arvin Ash and Anton Petrov and Sabine Hossenfelder occasionally say "if photons have mass then it's incredibly tiny", but **how** tiny? It being zero is important in so many formulas that we just cannot guesstimate or round this off or else galactic scale calculations would not match observations.
@@Yezpahr it's pretty common for people to use E=mc^2 which isn't the full equation. The full equation is energy squared equals its mass times the speed of light squared all squared PLUS its momentum times the speed of light all squared. E^2=(mc^2)^2+(pc)^2. E=mc^2 refers to "rest mass" and is used in nuclear binding equations. Light on the other hand doesn't have a rest mass so its energy comes from its momentum times the speed of light.
Thank you for reverting back to the old way of advertising the sponsor of the video. Inserting the ad somewhere halfway through the video was a very frustrating listening experience.
Imagine in a few decades we'll have Dark Physics in college in parallel with Luminous Physics.
I would definitely like to see more about this one.
i never understood why we had expected dark matter to interact through the weak force, more so in a specifically measurable way
What do you suggest? It's really because it's the only option left that can fit with our observations without completely upending the SM. If it were strong or em forces we'd probably have detected it by now and observations also suggests it's more than gravity. Anyways see WIMPs to read more about it.
@GRAYgoose124 why would we have detected if it interacted through the strong force?
@@geekjokes8458 To be clear, dark matter might not interact weakly, but that implies the SM could be in dire need of a replacement, and given it's success that's not something to consider lightly.
We call it dark stuff because we haven't detected it directly, but instead it's a correction that we need to exist to explain our observations of the universe with SM+GR. Either it's very massive or there is much more of it than ordinary matter. Either way, if it was strongly interacting, then we wouldn't only be seeing it in gravitational effects so late in the game to need to correct for it. Given gravity is so weak, the strong and em forces that would be appropriate to consider would drown out normal matter interactions and we wouldn't be sitting here questioning about the existence of a seemingly not-fundamentally-interacting thing.
WIMPs follow the chain of thought: there might be a mechanism causing dark matter to be more massive than ordinary matter, then to keep dark matter consistent with our observations, it could only possibly be interacting so weakly we haven't detected it despite its abundant gravitational influence. If they were massive particles interacting via strong/em, their force interactions would be enormous and be hard to miss in a particle accelerator or during chemical synthesis. If they were not massive, there would have to be so many more of them the lack of such events is inexplicable - unless interactions are weak enough to elude our experiments.
“But that hasn’t stopped theoretical particle physicists. Because when they say that dark matter only interacts gravitationally, they don’t really mean it. Instead, most assume that every once in a while, a dark matter particle will smack into a regular particle and interact via the weak nuclear force.”
I really wish people would explain the motivations behind such an assumption instead of just taking it for granted. Why do they assume that? What observations or experiments or even just philosophical reasoning supports that idea? Nobody ever says.
I find it absolutely hilarious that in astrophysics that everything in the past two decades are named after stuff that you expect to see in a Marvel comic book or a Transformers cartoon show. 🤣
Turns out, most scientists are geeks & nerds.
Similarly, SpaceX rocket designs have a retro Sci-Fi look resulting in SpaceX launch videos weirdly looking less realistic than Hollywood special effects.
As is tradition
4:05 Yes, but thats not at all how it works though?? Gravity has nothing to do with mass beyond mass being equivalent to an amount of energy. All photons have gravity.
4:46 Two things that never gets old
1. Jokes about Anakin killing the Younglings
2. The Younglings
The fact that light is actually something like a photon and nothing is also actually something like a photon is mind-blowing
Almost sounds like Dark photons are a polarization(?) of regular photons in the electric field, much like how the different flavors of neutrinos change identity depending on their distance from the source. Interesting!
This one was really interesting, super cool!!
2:10 I'm intrigued by this. Have there really been trillions of experiments with particle physics? I suppose it's possible, but that just seems orders of magnitude beyond what makes sense as a possibility.
Avagadro's constant really helps here, a trillion is only 10^12, one mole of material is 10^23. The LHC operates on beams of 2.8 x10 ^ 14 protons, so every particle experiment can easily net billions to trillions of collisions.
It depends a bit on how you define an 'experiment'; as a project or as a single test. The LHC for example is one single project, but conducts many individual tests each day.
@@jameskinardSure, but each collision isn't a separate experiment. That's not how laypeople *or* scientists use the word "experiment" - that's not even consistent with the way the video uses the term elsewhere within its script. I can't reasonably say I'm conducting quadrillions of experiments in genetics by counting every base pair that's part of transcription, translation, repair, and replication in my body. It was a silly thing for a science video to say and totally unnecessary to the point.
I got to thinking about this problem deeply and found it odd that spacetime curvature is the only thing that doesn't collapse the wave-function of photons and I'm sure that spacetime it self is the missing mass/energy in the universe. What I'm getting at is that spacetime seems to happen faster than c (it's the constant of constants hence no wavefuction collapse).
I legit came up with something conceptually similar to explain magical darkness in my d&d games and was blown away by stumbling across this video.
hamburger for lunh, and the a video with both science and Star Wars refferences?, this is the freaking best day of my life!
I always wanted to know if one can really trap light. The issue is that once you open the trap, the light escapes waaaaaay too fast to see if it ever stayed inside. I guess they are trying to use that idea to see if light will ever convert into something else to escape a trap meant for light-light
Energy will escape as heat pretty rapidly. My only guess here is that they would be trying to measure the rate as with that escape happens and see if it appears to be even faster than expected. Just guessing here.
well heres the other problem even if it did stay in it would well stay in meaning couldn't see it
although there is a way to know if you trapped some light as the container would get heaveir as mass is just energy thats localized
They have in fact stopped photons in place.
If a dark photon has mass, how can it travel at the speed of light?
E=MC2
because it doesn't suck
It's just built different
and even a miniscule amount of mass near the speed of light has a ton of energy.
It has "theoretical mass" and, therefore, is affected by gravity. It's like how when you're turning in a car and it feels like you're being pulled in one direction, but it's just the inertia of your body. That's how light is affected by gravity. The photons ride on the curvature of spacetime like a car on a banked, curved road.
The dark photon was literally a section of my Master's thesis! I feel nostalgic...
Calcite being an honourable mention means a lot to my calcite loving heart ❤️
I really enjoyed the writing of this episode
physicist goth phase
PHYSICIST GOTH PHASE
Hum.
Most say that gravity isn't really a force.
Also E=mc² is just the part for particles with mass, the more complete equation is E² = (mc²)² + (pc)²
And for massless photons, it is the (pc)² part that is non zero. Where p is the momentum.
But yes, photons do in some ways behave like particles with mass, precisely because they do have momentum.
This is how you get Necromancers...
I’ve never even thought about invisible light being made of photons, but it makes sense.
Lmao
Dark Energy equals Dark Matter divided by the square root of Dark Light
Now I know why it's called unseen.
I like the idea of photons as the "representatives of the electromagnetic force". Like they're the diplomats that interact with reps of the other forces, and matter.
My understanding is that gravity isn't a force. At least that's what a few physicists have said. That Einstein guy seems pretty bright, ya know?
This may shine a new light on particle fluctuation and even the double slit experiment.
The Universe is getting more bizarre by the day. I only just managed to wrap my tiny mind around black holes but this stuff is just crazy-pants. 🤯
"Propagators of Dark" will be my new goth-rock band...
If energy can act like mass in certain situations then is it possible that dark matter could be explained by interactions of highly charged energy creating a sort of virtual mass which would produce gravitational effects?
Light does this as it gravitationally lenses, but it also loses energy to the vacuum as it red shifts adding a bit to the expansion of the universe. I'm wondering if this dark light-like particle could be in large enough quantities, but with lown enough energy to be the culprit behind both dark energy and dark matter.
@4:05 photons and all mass-less forces/electromagnetism have zero mass hence why they all move at c (the speed of light). Seems like our detectors are not tuned to detect something faster than c or spacetime wakes. Spacetime it self seems to be black and mass-less and we have a hard time measuring it's curvature and speed/time-dilation without reference points and local sensors (think The Great Attractor for example). Another way I like to think about the spacetime wake/blueprint is time travel, if I just traveled back in time but not space I wouldn't end up on Earth (ever), I would also need to follow Earth's path back in spacetime making the distance long in space and time, this lead me to imagine a wake from where Earth has past back in time. The problem is that the Earth is moving in a very complex path through spacetime (corkscrew around the sun, that corkscrews around the milky-way, which is colliding with another galaxy while the great attractor curves it all)
"Dark Photons" What a great band name!
@2:30 but gravity is not a force, it's just spacetime curvature. People are thinking about this missing/invisible mass/energy all wrong, for all we know it could just be spacetime wake's we cant see bending light (it takes energy/mass to curve spacetime) so it's reasonable to image spacetime wakes like a worn horse track. The effects of mass/energy after a solar system or galaxy moves on from that spacetime frame would logically leave a ripple/wake/fingerprint behind. Also the law of conservation of energy basically imply's that something has to happen to the energy invested to curve spacetime...
Down with the Standard Model! Particles be FREE!
if there is a photon that spreads shadow than i NEED ACCESS TO IT
(for aesthedic purposes)
If there's some kind of cycling between states like there is with neutrinos, there might be some kind of other conceptual experiments to test the idea. Seems like you could map out concentric rings from all known radiating photon sources, with the ring spacing based upon the frequency of the predicted switch between phases. With various photon sources in a region of space, those plotted rings would produce all kinds of interference patterns with nodes and anti-nodes. So the interesting effects should be predicted to occur where nodes bunch up. Not sure how well a model would match a prediction, but I suppose that would be interesting to test out.
Having lots of data that constrains dark-matter possibilities is a feature, not a bug.
There is quark mixing. More recently, we discovered neutrino mixing. So now, someone has come up with a hypothesis of photon and dark-photon mixing. It would be nice to see what comes of that.
Now here's the big question: If dark photons have mass, are they then not light speed, and if so, what would their speed be?
But wasn't it also discovered that space is accelerating faster than speed of light? So that means dark matter is traveling so much faster imho
3:33
Let's see...
Dark photons have a small amount of mass, may interact via the weak force, and interact with gravity as well.
This is all described by Neutrinos. More discussion needs to be had about Neutrinos as a possible solution to "dark matter".
Yes, I had the exact same thought. I'm assuming scientists have ruled them out because we have estimates of how many there are, and they just don't account for enough mass?
That's sterile neutrinos, the regular kind being too light to behave like dark matter. That's far from a dead supposition, though generally neutrinos and photons aren't interchangeable.
Neutrinos are indeed a form of dark matter, but they tend to be fast moving ("hot") and observations point to "cold" dark matter being the bulk of it.
@garethdean6382
I'm a skeptic of "dark matter". I was suggesting that rather than inventing a new possible explanation for dark matter (this dark neutrino), scientists should go back to investigating neutrinos roles in the observation that led to theorizing "dark matter".
Hope this better explains my original comment.
@erinm9445
I'm doubtful we have good estimates on the number of neutrinos in the universe (both normal and sterile neutrinos). IMO, it seems that a lot of energy is being wasted (pun intended) on finding dark matter when we already have a good candidate.
I hope this better explains my thoughts.
We're already deep in our goth phase, thank you very much.
#Dark-photons can “quantum tunnel” through matter, reflective or not. But, only from below, if not within. 😮 5:45
I was NOT READY for that Star Wars reference ☠️
"OK, so what's the speed of dark?" -- Steven Wright
So, this is what "The Watchers"/"Jinn" are made of. Neat. 👻👽👹😃
i have some doubts about any scientists ability to make a perfect mirror box that wont absorb any photons
Or let any escape.
Obviously any photon in the cavity will be absorbed in a very short amount of time by human scales. But careful tuning of the reflectors and cavity shape will maximize the power in the cavity, and increase the expected rate of normal to dark conversion. The paper also discusses the risk of normal photons escaping and reaching the detectors, and how to prevent that.
Agreed, the best mirrors are made of silver, but those cannot contain gamma radiation.
I'm making a prediction there's a 'dark quantum field' out there. What the heck! They haven't experimentally observed dark matter, dark energy, or dark photons?
Hi Reid!
We should point out that light has no mass, no really, not even in that sense! E = mc^2 doesn't apply to photons since they have no rest energy. For them, the full equation simplifies to E = pc. And in general, gravity doesn't act on rest mass, it acts on _total energy,_ of which rest mass is one component.
It acts on total energy of a system, which is equivalent to the rest mass of that system. Gravity doesn't act on the kinetic energy of an object in motion, because that energy is relative and gravity is not.
@@erinm9445 Total energy depends on relative velocity. It's one way to look at the reason why you can't keep pushing on an object to accelerate to the speed of light -- its inertia (the Pythagorean sum of rest energy and kinetic energy) goes up the faster it moves from your perspective.
@@General12th Yes, total energy *of the system*. A system contains objects that have momentum relative to each other. All of that internal momentum contributes to that system's rest mass. But if you want to talk about the gravitational mass of a single object within that system, you still only look at its rest mass. That object is, after all, at rest from its own frame.
When you ask how much kinetic energy an object has, you have to ask, relative to what? But when you ask how much gravitational acceleration something produces, you don't ask "relative to what?" that wouldn't make sense.
So when you look at the gravitation caused by the earth, you don't include the kinetic energy of the earth relative to the sun or the planets (or relative to the Milky Way or the CMB), you only look at its invariant mass. But when you look at the gravitation caused by the solar system, then you include the contribution from the invariant mass of the earth plus the momentum of the earth relative to the sun and planets.
The explanation at @4:00 is slightly misleading, implying you only have gravity when you have mass. However, a normal photon should also be a source of a gravitational field, due to its energy-momentum, even though it has no inertial mass.
Perhaps the key point is that a "dark" photon would have a much _larger_ gravitational field due to that small (but non-zero) mass converting to a proportionately much larger energy (compared to its "light" photon counterpart) due to the c-squared factor?
I have heard a million different times that the Standard Model and General Relativity don’t work together, but why?
Like is it a problem of them making different predictions that are mutually exclusive? What is incompatible about them?
Oh, dark matter, the cosmic clown that's had astronomers chuckling for a century, and there's still no sign of a punchline that makes sense. It's like they've been on an intergalactic wild goose chase for a hundred years, and all they've got to show for it is a bunch of cosmic whoopee cushions that keep deflating when they sit on them.
Now, enter axions, the absurdity's absurdity. Astronomers, in their never-ending quest to turn the universe into a comedy show, have introduced these quirky particles into the cosmic script. It's as if they've decided to juggle flaming bowling pins while riding a unicycle on a tightrope that's on fire - you know, just to make the whole thing even more ridiculous.
Picture this: Astronomers, with telescopes pointed at the void, staring blankly at the cosmic canvas, suddenly shout, "Dark matter, axions, and...um, other stuff, I guess?" as if they're naming random things from their grocery list and hoping it will magically make sense. It's like trying to play chess with a set of Scrabble tiles - chaotic and utterly incoherent.
They've essentially turned the pursuit of knowledge into a century-long cosmic slapstick routine, where the punchline is eternally delayed, and dark matter is the banana peel that keeps astronomers slipping. Axions, in this carnival of chaos, are the cotton candy that's been flung into the crowd, sticking to everyone and making everything even stickier.
So, here's to our persistent astronomers, who've transformed the cosmos into a never-ending cosmic stand-up show, with dark matter as the bumbling, pratfall-prone comedian. Keep the popcorn handy, folks; this spectacle of cosmic confusion shows no sign of a sensible ending anytime soon.
We see the “surface” of “dark matter” indirectly through the tug of the universal fabric of spacetime upon our visible galaxies. However, the interaction of “dark matter” otherwise is performed BELOW the surface of spacetime within the interstitial boundaries of “as above, so below”. 😊 4:28
Dark matter is the radiation leftover from the "annihilation" of combining regular and dark matter. The leftovers is subatomic particles🤷
Dark photons are just regular photons in their Fallout Boy phase
"About 5/6th of our [Physics] we just don't understand."
How do we know that parts of things we think we fully understand aren’t influenced by dark matter or dark photons? Like radioactive decay… maybe dark something being everywhere all the time is partially responsible for the consistent decay we see in the elements.
It is getting more and more bizarre. Like observing the galaxies rotating like LP, outer arms not slower... Everything else we observe on a smaller scale shows a lag in the outer edge if not forming one solid mass altogether. Or is it because there is not much medium like we have air on Earth that slows the rotation further from the center and that galaxies are usually so far from each other that even their mutual gravity is too weak?
Could the light photon ∆E=hf form the characteristics of time with the exchange-quantized energy continuously converting potential energy into kinetic Eₖ=½mv² energy of matter in the form of electrons forming our ever-changing temporal world?
About the light through wall experiment, isn’t matter mostly empty space meaning that some photons will escape regardless of if it turns into dark photons or not? Please correct me if I’m wrong.
0:05 - "You can head to drink..."
Me - "Okay, see you later. I'll go and drink a toast to you!"
I think I saw this TV show, the one with the androids, the serpents, and the dodecahedra.
Makes me wonder if Neutrinos changing type is related. Or what if the Standard Model is just one corner of a multitude of standard models all active in the same volume but rarely interacting, like subspace or alternate dimensions in fiction.
Btw to explain why light doesnt have mass even if E=mc2 if youre confused
its that that is the version for an object without motion in a point of view, but the whole thing of relativity is also that photons are always in motions no matter the point of view, so they follow a more complete version
E2=m2c4+p(momentum)2c2
so the energy light is not mass, but does mean it can transfer momentum, as seen in solar sails
Oh its an idea for space propulsion that a lot of people talk about
basically, have an object in space deploy a huge surface, and use the momentum from the light of the sun hitting into to propel the craft and it will slowly build up speeds@iro4201
I love how the Light-Shining-Through-Wall experiment once again confirms my bias that researchers have zero talent for naming things. This isn't why I didn't become a researcher, but I'll pretend it is, just because it feels like a moral imperative.
Can you do a video on a way to save the universe from the Big crunch or the big freeze or the big rip if there is a way theoretical or not
I'm going to go out on a limb and say these experiments will come up as empty handed as every other dark matter particle experiment has.
Even it does we should learn something. Science is fun like that.
"Blue shading indicates our ignorance" FTFY 0:40
I have often thought about wavelength of photons being stretched as they traverse the vast distances of intergalactic space. It does not seem impossible for the wavelength to become so long that the wave function describing the energy is so dispersed in space to be inert with anything else locally present. It is not inconceivable to me that the energy traversing through space may be so stretched out as to be undetected by us in any other way than through the vast bulk observations at galactic and intergalactic scales. The universe is likely filled with these very long photons that we have no hope of ever detecting. I am thinking here about photons with a wavelength on the order of light years in span.
What happens to all the stretched light after billions of years, what does it look like and does it burn out?
A mirror box will just act like an energy barrier. The photon could just tunnel through it the same way an electron tunnels through energy barriers.
So, we're back to the "Ether"?
I never stopped believing in it.
3:52 e=mc² is only for particles at rest, not photons that are never at rest....
e=mc2 is just a simplification of a more complex formula that is lesser known, but you can make the appropriate adjustments.
So, we're figuring out how the universe turns the lights off and on.
Leibniz also hypothesized a thing that could not be detected. You can't prove it doesn't exist ...
The speed of light isn’t constant since time and distance aren’t constant.
Given that light loses energy to red-shift into the expansion of the universe and that massless particles can still effect gravity with their momentum, what if there where just an extremely large number of light like particles losing energy to the vacuum and causing gravitational effects, but in a mostly non-interacting field? Each particle would be too low energy to detect by itself, but it could potentially be creating what we see as both dark energy and dark matter. This is purely unresearched conjecture on my part.
It’s crazy the universe we live in
What an invention
The comment about younglings . . . that was dark
This video explains everything but what a dark photon is. Come one guys
DM is just kuggelblitz's and high energy photons
"if the amount of light vanishes from the box, that means some of it must have transformed into something that can tunnel through walls"
but isn't quantum tunneling already supposed to be a thing with pretty much any matter? theoretically? at subatomic levels etc?
so if that happens, it doesn't necessarily mean the light transformed, it might mean some light just quantum tunneled out.
Yes, however tunneling depends on distance. Two hydrogen nuclei need to be VERY close to have a small chance of tunneling,but the water in your body isn't undergoing fusion. A thick enough wall will easily reduce the chance of tunneling down to the likelihood of the boxes atoms suddenly fusing into gold.
@@garethdean6382 I'm confused.. what does fusion have to do with tunneling?
wow that was a lot of starwars spoilers for a video on the dark side of physics 😂
Why do we assume spacetime is flat to begin with? If it wasn't, then large masses like black holes and galaxies would tend to settle into the dips. This would explain why they would form so soon after the BB and also why they rotate faster than their own mass would suggest they should. This would also explain the accelerated expansion of the Universe. Spacetime is far from flat! And we don't need any internal reason for that to happen.
What if the seemingly random nuclear decay actually IS dark matter interacting through the weak nuclear force, and that's why it's seemingly random?
I will henceforth invariably see gravity as a mime...
4:35 If a dark photon had mass, it wouldn't be a photon. If a photon turned into a dark photon, it would have to gain mass and would no longer travel at the speed of light. Photons like all other force carriers including the theorized graviton, are massless. If I know this, physicists know this. So I don't understand the hypothesis. 5:18 - "light shining through wall" (old news from 2013) and NA64 have found no evidence of the interactions after a literal hundred billion particle collisions. It is easy to understand why. At least we've made progress proving it doesn't exist.
2:33 I hate to be a pedant but I thought scientists say that gravity _isn't_ a force?
Go Go Sci Show!