Why Doesn't Light Have Mass?
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- čas přidán 19. 06. 2024
- Of all the things we can actually see (directly), we say light is the only one that doesn't have mass. Is this true? How is this possible if it has energy?
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For anyone who has complained or wants to complain about my explanation of the Crookes radiometer, I've posted a more detailed video on it: czcams.com/video/Li_nmKw4Buc/video.html
Also, here are some other follow-up videos because this video was a mess:
What the HECK is Mass? czcams.com/video/XkPudRiWspc/video.html
Momentum does NOT require Mass!! czcams.com/video/LoadZQkrfcQ/video.html
Damn it, I typed a big comment explaining how light mills work and then I saw this pinned comment... I deleted what i wrote, most of it was explained in your followup-video. But I also wrote something about blackbody radiation/absorption and why good heatsinks are black. But I have deleted my comment. ;)
By the way, I love it when somebody makes mistakes and realizes it. It results in re-thinking and learning. If the error is in a video and there are discussions about the error in the comment section, the better it is. ;)
But... light DOES have mass. It just doesn't have rest mass, but since when can light be at rest? Therefore, saying light has no mass is a LIE. :)
Its mass is exactly the energy level of the photon divided by the speed of light squared. The energy is the frequency times planck's constant. So... not... much... but it still has mass in every possible form it can take, since a light photon at rest doesn't even exist. It would also mean green light is heavier than red light. Higher frequency of light means more energy, which means more mass. :)
Dangit... a photon has no REST MASS. Saying it has no 'mass' is straight up wrong. A photon can never be at rest. It is confusing, but realize the fact that photons move, they have energy, and therefore they have relativistic mass, the only mass that actually exists. Anything with REST MASS cannot travel at the speed of light, as it would require an infinite amount of energy. Rest mass is not actually a real thing, it is a virtual concept since nothing can ever be fully at rest. IF something could be cooled to absolute zero so it had zero momentum, that would be its rest mass. Thermodynamics forbids this entirely. But if you could force a photon to be at rest, it would no longer exist. Think of light as a sound wave for a second. If the wave doesn't move, it cannot express its frequency(energy level). This is why it has no rest mass. This is why it can travel at the speed of light. It's relativistic mass(the actual mass of photons) is derived by its energy level(the frequency) divided by the speed, the speed of light. A very tiny value, but it has mass, the only mass anything actually has, relativistic mass.
I don't know what you mean by they don't exist. Of course they exist. I think you mean the concept of a photon being a solid object doesn't exist in reality, or that a photon at rest does not exist, which I already stated. Photons are just packets of electromagnetic energy. Any and all types of energy gains mass through relativity.
@Hand Solo
Photon have mass. Its easy to prove by using simple logic. Photons are energy. Energy = mass.
Mass of the photon is smaller than 1 x 10^-18 eV. Thats it. Our current technology dont have enough resolution to detect this mass because its super tiny but its there. So now we say that mass is smaller than this value.
In 100 years technology will improve and people in XXII century will be able to detect it.
Another thing. Nobody knows what is really happening when you travel at the speed of light. Because no one so far can travel that fast.
We have models, theoretical models but theory is one thing and practice is another.
"The more massive something is the less willing it is to change how it's moving."
This explains why it gets harder and harder to workout out.
Ah ah ah
This make sense, because when you go to work out for your first time you build muscle very quick and you can feel the change very quick. But after working out for 2-3 years straight you have to start really increasing what your doing to start seeing more and more change
This is the funniest thing I’ve heard all day
Is this a joke Americans? Lol.
As an american I could pretend be offended, but I don't really care about America that much anymore.
Once you start working out it's harder to stop haha
Currently blitzing through “light has no mass” videos; determined to get this in my head today. This was a good one, cheers.
This one might also help: czcams.com/video/XkPudRiWspc/video.html
I think the reason it might be confusing is because we think of photons as little balls moving thru space, but really they're waves of pure energy that travel in discrete packets and for this reason they have properties of both particles and waves. Also the faster you move the more time contracts and the faster time passes on the outside. Since, photons travel at the speed of light they experience no time, from their relative perspective they are absorbed instantly after being created. I think that's a lot more trippy to think about than photons not having/being mass. Also mass itself is just like a really complicated arrangement of energy, photons are just pure energy, "not arranged into mass". So its not that they don't 'have' mass, but rather mass is just one possible arrangement of energy.
@@gabrielmalek7575 interesting perspective, did you get this notion of mass in à spefici arrengment of energy in à physic class or a lesson?
That's why light is the fastest thing around I guess
@@gabrielmalek7575 what's a photon then? How can we talk about it as a little particle? It's not a particle it's a wave, but then it's not a wave it's a particle lol. I can't get an understanding lol
This is how I think of it, based on what I've read and learnt: mass is energy in a box. A photon doesn't have mass, but if you put it in a mirrored box where it bounces around endlessly, then the photon adds to the mass of the set-up...
a similar thought experiment leads quite naturally to the mass-energy equivalence: Take a box with a light source on one side. Switch it on; the light has momentum and thus shifts the box backwards a little. When the light hits the opposite wall the momenta cancel and the box is again resting. Since nothing else was interacting, the centre of mass must remain motionless throughout, resulting in a relativistic mass being transported within the box eual to the energy the other wall absorbed in the process. Sadly, this approach does not yield the full energy-momentum-relation.
Nick lucid. Please make a video on this photon in a box having Mass comment. Can light create Mass????It's making my head for a loop. PLEASE make a video🙏
@@westonriner7264 Yes it can create mass, it was explained in the video how mass and energy are interchangeable through special relativity. It's presented in the stress energy Tensor and an example of energy in a box is given as a kugelblitz. The inverted formula shows that energy and mass are interchangeable and as was explained in the previous comment since a beam of light in a box is constantly canceling its momentum while bouncing inside the box then by default it remains at rest within a closed area of space. You can see it noted in the equation on the video. Visualizing this is difficult but as it was explained in the video suppose you were to reverse the fusion and put those millions of sedans worth of energy back into the sun and reverse fusion, you'd be increasing its mass.
Here's the thing that gets my brain cranking gears when it comes to mass/energy, the idea that energy can be transferred through space via gravitational waves. The bending of spacetime transfers energy and as shown via gravitational wave astronomy it's also restricted by the speed of light despite the bending not being made of photons. Also that despite black holes not letting anything escape their event horizons they still lose an extremely large amount of mass during their collisions via gravitational waves.
I've sort of learned to deal with this in the same way I've learned to deal with the fact that lifting a brick and dropping it on my toes is painful because of the potential energy I gave the brick relative to my toes. Sorry if this made no sense, I really am not a very good communicator when it comes to this and I'm not sure I fully grasp the depth of it myself.
Never stand between two mirrors. Never cackle. Do what you must do. Never lie, but you don't always have to be honest.
@@Plasmon19 Electromagnetic waves is one of the fundamental forms of energy. but electromagnetic waves don’t curve space time, do they? The way I understand it is The only time electromagnetic waves bend space time is when they wrapped up together to make a particle. Then that particle bend space-time a.k.a. has mass. What is the fundamental property that gives something mass aka the capability to bend space-time????
I want you to know that you are amazing. In less than 5 minuets, you did a better job at explaining why light has no mass than 4 of my professors and 2 high school science teachers ever did.
Iight can never be at rest relative to you. So light will always have 0 rest mass relative to you.
Nick Lucid, You have an incredible talent to make science easy, fun and interesting. Thank you and keep them coming!!
Same by me!
Having science in a fun way is mentioned by...
Science = Awesome
😉
germain drouet yeah
Neil on This Grass Tyson would learn a thing or 2 watching you. He's smart, but his enunciation and ability to transmit his thoughts is cringe at best.
Most amazing science channel
Don't forget he's crazy
how can this channel not have 100,000+ subs? The work you put in is nuts!
We need to start sharing more :P
because everyone is busy commenting this same comment each video and not sharing!
Yes, please share :-) Preferably with bigger science CZcams channels. All it takes is one shout from someone with a larger audience and we can take crazy science to the masses! (pun intended)
MusicReviewFication I agree, I love his videos. Subscribed within the speed of light!
+hardino0311 any speed within the speed of light could mean anything lol
This channel is freaking amazing, this video alone made my conception of mass do a 360° turn. Keep doing what you do and thank you for your great work.
Thanks! But I feel like I did better when I came back to the topic here: czcams.com/video/XkPudRiWspc/video.html
You mean a 180
@@jayde4872 nope. It make him be satisfied with the answer but then doubt himself again
You see the exact same thing when you do a 360 degree turn aliensjvwbwjs whatever
@@aaravkokkain4315 yes not what hes talking about. It make him be satisfied with the answer but then doubt himself again
Brilliantly put. "Mass is just the energy contained in an object when it's not moving". Great video!
Light has no mass because it isn't Catholic.
Norman Morgan good one bible basher
" I am the light". (Source: God).
If you look at certain depictions of Jesus the sun is used as kind of a halo around his head.
Norman Morgan . Neutrinos go to Mass . Ha ha .
Norman Morgan sir I dont think so because light shows the dual nature .
1. Wave nature of light
2. And Particle nature of light.
So if we could assume that wave does not have mass but particles have mass.
3:09 These twins create some good content! His brother asks the questions and the other brother answers them! Genius!!!
no he didn't answer anything
Time displacement twins. They are the same person, in different locations in time...
Clones, they are clones.
This is one of the best science videos I've ever seen for someone with enough background to put the pieces together fast enough...but more I think it is about the way a physicist thinks. It captures beautifully the constant debate of cause/effect vs definition, the almost glib first thoughts vs the mathematical models that follow, and the manipulation of mathematics as a tool, with respect, but a loose swing of the arm.
I am so excited that I found you! What great videos!! You have a amazing way of explaining things in a really fun and funny way that keeps me smiling while learning. I have learned more through you than all my school years. And I’m 46yrs old! Bravo!! Thanks for your hard work in making all these informative videos.
"It's OK to be a little crazy". I'm glad he mentioned that, because up to that point I was getting a bit worried.
Why does light doesnt have mass?
Because it doesnt matter 😂
oooh 69! don't break the cycle
@Phoenix That's heavy man...XD
@Phoenix But gravity is not a force, or so I'm told. .
Guess, it's immaterial (in the vacuum of space).
Lol
How do you not have more subscribers? Your videos are by far the most informative and you are able to explain things in a way I can understand. Good luck and keep making videos!
Thank you so much! I couldn't find any other explanations that made so much sense. The extra parts of E = mc^2 made all of the mass/energy/light questions I had disappear! I'm making a video for the Breakthrough Junior Challenge this year and this was part of my research so very helpful and important!
that was truly informative to me.
Yay!
Same thing i was gonna say
you have cleared one of my doubt, thanks and subbed!! :)
I wasn't expecting to find Nebuch here
Most of his videos have had that effect on me...barely found him
I learned one very important thing from this video
I need to go back to class!
Lol!
"Light is the exhaust of the sun"
Pure gold. I'll go outside, soak in some exhaust stuff and feel healthy
You literally make science as fun as never before 😀😁
This channel is fantastic and needs more exposure. You have such a fantastic style of teaching.
Thanks! You can help with exposure by sharing the video on social media (especially with educational CZcams channels with larger audiences).
Congrats for 10k Subs. I have been posting your videos in social media. I sincerely hope it helps such a nice channel. Keep Going !!!
Your work is truly great. Just slow down the tempo a bit - mainly in editing, and you will probably appeal to a much larger audience. It's all interesting, but let the hard facts sink in for at least a couple of seconds sometimes. Thumbs up as always!
Yes. It's too fast. But one can always replay...
The problem today is that many people don't have patience. Especially the patience to replay.
You’re videos are genuinely so interesting to watch! Cant wait till more people discover how awesome your channel is
you must be on drugs
"You are videos..."? "Cant..."?? 🤦♀️
Keep up the fun science learning and please distinguish things more in details!
I love this channel!
Learning science in a fun way makes it awesome.
Think, why do normal science classes feels like so boring or takes so much time to get over?
Ans. : Cause its not fun!
So if we replace that with a fun way than we might actually like it and take terms like General Relativity easy!
So, that's why I love this channel!
😉😉😉
Amazing videos! I just found your page a few weeks ago and am absolutely loving it
How dare you make physics interesting! 😊😊😊
Great video! Thanks for sharing! 😆
infotainment ftw!
I absolutely love these videos. They are so user friendly and informative. Thank you.
Glad you like them :-)
Absolutely fantastic approach to learning. You follow the questioning and failure to understand that most people go through to really help connect the dots.
This is the most incredibly mind blowing video there ever was or will be!
Watch some pbs spacetime...no offense, These videos are just as amazing!
I just found the channel. You make a great job here! Im subscribing.
Susbcribed!! U deserve it for ur efforts.
no he doesn't
understood!!! thanks for making such wonderful vids. I think you should have at least a million subs
just discovered this channel your vids are awesome
Thanks! 🤓
This Channel needs way more subs!! Really good content
no it's trash
My dear nick I saw one of your videos on Sunday night 3-11-17 it’s now Tuesday 5-11-17 and I’ve just seen the last one in your series I am hooked like I’ve never been hooked
on any thing before, your character your your presentation your humour your questioning most of all your passion to teach people like me oh by the way I’m not very well educated you lose me on most of your topics but I get the just of what you’r teaching me I’m sorry nick but one video a week or a month just is not enough especially a four minute video you’ve got to work on that I guess what I’m trying to say say is thank you nick if you were my teacher when I was at school I would be made up and educated I am now 57 years of age once again my friend thank you and don’t stop making them cheers John
Glad you found the channel :-)
This wasn't so bad. I think more complicated is transferring momentum from light to objects (light sail). Why most of light energy is converted to heat and only small percentage to momentum? Do you get more momentum transfer when the object is dark or reflective? Is there a way to control the ratio and have ligh transfer more momentum and less heat? Do light source experience recoil?
Your videos are just so great! Makes me remember why I once loved physics so much and also, that love is slowly coming back to life!
It will take me more watches to comprehend this
Especially because it's hard to get passed all of the unnecessary yelling
@@bicboi1930 And the unnecessary negativity in the comments.
@@Triairius it's called constructive criticism
@@bicboi1930 There's a fine line between negativity and constructive criticism. In this case, it's not very constructive, since you're telling someone other than the person you're criticizing. Additionally, the word choice does not create a tone of trying to help, and it comes across more as negativity, whether you intended it that way or not.
^. Answer to his question. Yes? Hint his question was not a yes /no question. Just one I have to understand first
I'm laughing and I'm exploding my head and I get three per cent of what you say but I just love you man!
you get exactly nothing because there are no explanations
# metoo
:)
So do I 🤣🤣🤣🤣
I very nearly snorted tea out of my nose on seeing the dramatic hamster lol :D
When I was in the Navy many years ago, I was placed into the Nuclear Propulsion Engineering Program, which was in Orlando back then. We were taught that a photon had "instantaneous" mass, which I never really understood.
A Higgs Bosun walks into a church.
The priest says "you don't belong here; you're not a person."
The Higgs Bosun replies, "without me, you can't have mass."
The priest looks thoughtful and says "the gravity of your argument adds weight to it." ;)
your clever joke amuses me
Higgs BosOn
What is a "bosun"?
@@jojolafrite90 A hindu boson.
E=MC2 joins the chat
To all Science Asylum team: thank you for your work. For me and all non experts in math, you rock.
the end was nice - the complete formula makes it easier to understand
Totally subscribed!
Great channel! Funny and informative. However, I have a correction. At 2:53 you bring up the Crookes Radiometer and imply it rotates because of the momentum of light. This is not the case. You said you "removed the air to avoid any complicated thermodynamics," but thermodynamics is exactly what causes it to spin. There's a small amount of molecules left within the bulb (it's only a partial vacuum) which allows differential heating from the black and white sides to have maximum effect and spin the "blades". The loss of momentum of the light is an unimaginably incredibly small contribution to the rotation. There's a reason solar sails have to be so large and light (excuse the pun). I love your channel and hope it grows!
You're not the first person to mention this. My Crooke's radiometer is custom (it's not one you can just buy). I have plans of putting out a video on Radiometers soon. In hindsight, using a custom device just to make a point was misleading. I apologize.
That's awesome! How did you order such a thing? I apologize for assuming. I didn't know that was possible to just use the momentum of light. Do you need a lot of light to get it spinning?
You need A TON of light, a NEAR PERFECT vacuum, and an EXTREMELY LOW friction environment... and lots and lots of patience. It's not easy and you can't order one (you need fancy equipment). It also doesn't spin as fast as it does in this video (I sped it up, which makes it even more misleading). Like I said, I have serious regrets about even including it. It's just that the radiometer gets used in intro physics classes a lot as an example of radiation pressure, so I forced it. I should have talked about solar sails or stellar equilibrium or something. I will be correcting this error with a full video soon.
How fast did it actually end up spinning and how long did it take?
Do you know Einstein actually did a paper on the Radiometer effect?. From my reading of his paper on it, he seems a little perplexed on just how why it works. My view on the radiometer effect is that is a very poor means of examining this perplexing problem of interpreting E = mc^2 or m = E/c^2 as wrote that equation in his Sept '05 paper.
Watched one video.. instantly subscribed. Your detail is amazing
what detail? are you dense?
@@Mr.Caligos Well, for one thing, mentioning that e=mc^2 is only half the story is new to most people, I would think.
@@Mr.Caligos Boi, why you don't get constructive and use your channel and explain stuff to the masses (no pun intended :D)
thanks 4 sharing, I've been learning from ur videos,
This video has answered one of my most confusing doubts about light. Keep it up Nick!!
Finally! I have been told by many people that “matter” and “energy” are the same. That relativistic mass is a thing, when Einstein himself discarded that theory.
This channel is awesome.
TSA, thank you for sharing an amazing video yet again. I feel lighter 😉😉
Me too.
Pardon me if I am missing something... but light speed, according to Harvard can be slowed down, even stopped by other experiments. Please correct me if I'm wrong.
not slowing but taking a longer path.
which takes longer so slowing without slowing lol
1:42 - hilariously placed.
brilliant content mate cheers
I love the way you explain all those things keeep going.
congratulations! you just won a subscriber!
Love your videos buddy!
Thanks! 🤓
Another good presentation. Thanks.
DIDN'T KNOW THAT PART OF RELATIVISTIC ENERGY EQUATION. GOOD DISCUSSION AND THANKS.
Great explanation! Dealing with energy and momentum is a better way. Their reciprocals, time and space.
Always had this question but never bothered to look into it thanks 👑
One of your best vids, I get blown away every time I see this video!!
Really? Huh... I consider it one of my worst. Definitely in the bottom 5.
Well, I am amazed how is it one of the worst
I've recommended this video at school too🙂
Yes, please do a vid on the difference between relativistic mass and rest mass.
And keep up the fantastic work!
Yes, would love to hear your explanation of relativistic vs rest mass
Well, you're in luck! I made that video last summer :-) czcams.com/video/XkPudRiWspc/video.html
What a beautiful explanation 😄
@SIR NICK LUCID
KEEP MAKING THE VIDEOS LIKE THIS.
THESE ARE WAY MORE EDUCATIONAL AND ENTERTAINING TOO.
HOPE FOR YOUR WELLNESS.
LOT OF HONORS TO YOU.
amazing channel... wanna see it grow bigger n bigger!
QUESTION:
I read somewhere some1 asking If a warp drive could escape a black hole when it has gone past the event horizon?
I didn't answer it on the original thread bcoz couldn't find the original thread again.
But I think, if the black hole is supermassive then the spacecraft would get past beyond event horizon without spegettifying, and should be able to escape given the energy it needs to expand and contract space itself faster than the blackhole can bend (since the expansion and contraction of space is not bound by the speed of light).
BUT, FOR THAT THE SPACECRAFT HAS TO EXPERIENCE TIME INSIDE THE BLACKHOLE, FOR WHICH IT SHOULD SOMEHOW BE ABLE TO ISOLATE THE LOCAL SPACETIME BUBBLE IN WHICH IT IS CONTAINED.
ANY THOUGHTS ? lol I guess I went completely wrong
Agreed! (Y) but consider putting warp drive in the scene since it does not move through space rather compressing and expanding it.
First, while warp drives are technically a solution to general relativity, it requires a mass distribution that currently seems impossible.
Second, an event horizon is what you get when events are physically removed from our spacetime. If your ship represents some of those events, I suspect you still wouldn't be able to get out of a black hole even with a warp drive.
***** Thanks for the reply Nick..😊 But I'm 99% satisfied with you you answer. But I know why.. the topic itself is not really satisfying...
just thinking as well, considering the effects of time dilation, as you go past the event horizon you see the future of the universe play out and even witness the death of the universe. the black hole would have evaporated due to hawking radiation long before you could even think of attempting to get out of it.
Lacerations just read my comment once again no offence
Mass is just E that has “condensed” upon cooling like dew on your garden :-) Great stuff- thanks!
Thank you again! 再次谢谢！
I specifically asked this question into Google to find your channel. I think this helps. It makes sense sometimes
I love it how he talks to him split self.
wow your teaching method is outstanding . Great job
Cool video....great description of light and mass
Thanks! I went into more detail here: czcams.com/video/XkPudRiWspc/video.html
Very useful video thanks
I love the way he scratches his non existent goatie beard😆
I dont mind letting go of the concept of mass at all since mass is energy....right?! Lol. Ps. I forgot how much i like your videos. Nice job.
terrible job
thank you so much for your help
His expressions are hilarious😂😂😂😂...Enjoyed coming here
i love his EVEN nerdier alter ego
Hey Nick. I noticed you said in the video that light must always travel at the speed of light. However, I've read about how a group of scientists stored light in a crystal and kept it still for 1 minute. I'm really confused as why was that possible. You reckon you could do a video about it somewhere in the future? Best wishes.
I have plans...
It is still travelling at the speed of light (see: refractive index on wikipedia). There's a whole complicated shpiel about how the electromagnetic wave interferes with the em field of the material, which sets off a delayed "echo" wave. The light wave is a superposition of both the original and echo waves, with typically the same frequency but at a shorter wavelength. This leads to a slowing of the wave's phase velocity (which would be the speed of propagation I think?)
I probably got it wrong, looking forward to watching a good video about it.
without mentioning *actual* speed, the 'speed of your car' is 'the speed of your car' :P :D
the speed of light **does** change, that is how rainbows and lenses work!! :)
erm wavelength is the reciprocal of frequency, one cannot change without the other..
as the entry says, 'the refractive index of water is 1.333, meaning that light travels 1.333 times faster in a vacuum than it does in water.'
'phase velocity' is the rate at witch it changes phase, see wiki.. :)
No, but light's velocity can be changed by reflection, refraction, diffraction, etc.
5:19 I don't know for the stars but for galaxies a few years after the Big Bang
There were some quantum fluctuations which caused differences in energy and matter densities which attracted the other smaller dust clouds closer to them forming galaxies. They were stabilized by dark matter and they spin I guess because the dust clouds differed in density by a small amount, both were attracted making them spin like two neutron stars
And yes it collapses into stars by creating its own gravity
Nailed it. (Almost flubbed it with mass-to-light conversion, but you saved it with a pop-up caption "Almost...". I presume that refers to the solar wind, which is ions.)
Yeah, just had to acknowledge I was simplifying things a bit. Solar wind is ions. There are also lots of neutrinos coming out of the Sun.
I appreciate your explanation, maybe a little more detailed however.
Peace.
I agree that I definitely need to come back to this.
@@ScienceAsylum up
I always thought the p was for the Latin word pmomentum.
Nice video! you are super!!
Very cool! ✌
Thank you! Screw relativistic mass.
2:45 I'm making that my cover photo 😂😂😂
HAHAHA
I really appreciate how you explain these (to me) incredibly hard to fathom ideas. I wondered if a photon's kinetic energy affords it any mass? I apologise if this question sounds a bit daft.
The laughs per minute in this one was off the charts hahaha
Holy Relativistic Jesus, you pronounced my name correctly! Bien joué, Monsieur Lucide!
You're welcome! Names are important.
To me it was very strange because the only people who ever say my full name correctly are people I know. So even though I know you as Science Asylum Guy Nick Lucid, some part of my brain was trying to process the evidence that we must have gone to high school together or something.
light might have mass that's why it's speed is limited,we might find a more distinctive particle which travels faster than light!!then mass will take a different meaning
I don't think so. I'm pretty sure photons don't have mass because they don't interact with the Higgs field. Therefore they travel through space at the maximum possible speed. The reasons get a bit technical for me to try and explain, but the PBS Spacetime video "The Speed of Light Isn't About Light" does a good job of explaining it.
Light is electromagnetic wave and wave have propagation speed.If you want to understand more search for the wave equations.
Set a scale outside on a clear day at high noon & trying weighing Sunlight.
If you can weigh Light, then it has mass.
I guarantee that you cannot weight light.
Yes if you practice you can hump faster than that speed.
Superb !!!
This in an amazing video. Congratulations
Really? I feel like I did better with this one: czcams.com/video/XkPudRiWspc/video.html
I currently have physics in school and i just lectured my teacher about gravity and centrifugal force... Thank you :)
Btw love your channel;)
Awesome!
If I were your teacher, I would throw you out. Jeez.. Imagine having a few of those every year.
Ronald de Rooij - on the other hand, if he was my teacher, that would _really_ rock!
:) any teacher worth his salt would be very proud of you!!:) :)
I know a few that say the students who 'get it' make it worth all the work!!! :D
the rest mass of a photon is relativistic-ally small. It is there though
No, any mass at all would diverge at the speed of light.
it can also be mentioned that the concept of acceleration doesn't apply to light , when you tun on a light bulb , the light comes to you at the speed of light, I doesn't go 1km, 2km...300,00km per second it always "travels" at the speed of light
Thank u for answering all the questions which I was frightened to ask lest I sound silly.
You're welcome! If you want to understand "mass" a little better, then check out my follow-up video: czcams.com/video/XkPudRiWspc/video.html
2:31 Light ALWAYS moves in straight lines?
I thought this was NEVER so, as gravity always distorts light's path?
This is getting more confusing all the time.
Even around gravity it travels in "straight lines" ...it's just that gravity changes what straight lines look like.
Ok, thank you :)
So light isn't bending but just looks like it is?
Mike Young When it comes to warped space time, straight lines can make full circles. For example, a satellite orbiting earth can be moving in a straight line, although it doesn't seem like it. The reason for this is that it is still moving in a straight line relative to the new shape of space. So, light which is bent by gravity is still moving in a straight line locally (on a very small scale) and the light simply follows the path of the bent spacetime.
You can watch PBS Spacetime's video "Is Gravity an illusion" here on CZcams and the other videos of that series to learn about it. Einstein's Relativity is absolutely insane.
Frans Hartman A simple way to demonstrate it is to draw a line on piece paper and then crumble the paper. Line is still straight relative to the paper.
This was fully informative buttt5t No bro I am not satisfied with this answer. Plz give more detailed video .
Mass is kind of an illusion.
Energy is what causes any kind of matter to exert gravity (aka curve space time)
Things also have inertia. Which is a bit more difficult to explain.
This is a crappy example, but okay. If you created a massless, hollow sphere, that is perfectly reflective inwards...and you filled it with photons, bouncing around randomly, it would gain the effect of inertia (even if the sphere is at rest...the photons bouncing around inside will never be at rest). But the average vector speed of those photons would be zero.
The more light you insert, the greater it's inertia. You would experience it to have "mass".
If you push on the sphere (try to accelerate it), light heading in the opposite direction of the applied force, will hit a part of the sphere moving towards it and gain energy. That photon's frequency will increase. (it will be blue-shifted). Where is it getting that energy? From your push on the sphere. It kind of absorbs your hand's energy, making it feel as if that massless sphere has mass.
Photons heading away from the applied force on the sphere, will hit a section of the sphere that is moving away. Thus those photons would be red-shifted (it's frequency will decrease...aka have less energy...via the doppler effect.). Those photons will lose energy to push the sphere forward.
So even if you stopped pushing the sphere (stop accelerating it), it would continue to move. If this is happening in space, the would continue at a constant speed.
Also, trying to accelerate the sphere further would require more and more energy, because photons heading in the same direction as the sphere would take longer to reach the other side to release energy. But, those photons would return faster.
You'd need an infinite amount of energy to accelerate sphere to the same speed as the photons bouncing inside it. But the sphere's total inertia (momentum) would increase infinitely instead.
Increasing the total energy of the photons inside that sphere causes the effect.
In an atom, there are subatomic particles moving around very fast. Contained by fields and forces.
A proton is kind of like that sphere except it has quarks whizzing about, held close together by gluons.
Tyler Durden this doesn't sound right. Why would blueshifting or redshifting light oppose a resistance on the sphere? Also wouldn't this "Doppler effect" (I know you're just making an analogy here) depend on the observer? You pushing would see it one way, but someone seeing the sphere moving towards them would see the opposite effect. As a whole the nature of inertia is quite mysterious, it just seems to be a property of things like electric charge, and the way we measure this inertia is through mass (or momentum).
A recent albeit untested theory tries to explain inertia through Unruh radiation: it's kind of similar to your example but what is actually "pushing" or resisting acceleration are virtual particles generated by an event horizon at the end of your light cone. Check PBS for a more on depth look.
Also worth mentioning that the mass of quarks and elementary particles has a totally different nature altogether: it's generated by the Higgs field, through a "drag" mechanism.
@@FunkyDexter Inertia is just an expression of conservation of energy. There is nothing really mysterious about it. You put in energy to get a thing moving, and if you want to stop it, you have to take out the same amount of energy. This doesnt change for another observer - you will both agree that the velocity of the object changed.
Excellent...getting crazy