Relativistic Momentum and Common Sense - Why Physics Theories are Counterintuitive
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- Опубликовано: 12 июл 2024
- Momentum in Classical Mechanics looks different to Momentum in Special Relativity. But why is that?
Hey everyone, I'm back with another video! This time we're using Relativistic Momentum, and Classical Momentum, as examples to talk about why certain tricky to understand theories (e.g. Relativity and Quantum Mechanics) happen to be the best descriptors we have right now of the universe.
Firstly, let's start with the basic idea that classical physics is generally considered "intuitive" to most people. The objects described by this branch of physics end up behaving like our day-to-day experiences, and our expectations, tell us they should. But classical physics famously breaks down when considering objects moving at large velocities. Anything that moves at a considerable fraction of the speed of light needs a relativistic description. And special relativity really is mind-bending, introducing ideas that don't make intuitive sense to most people, such as the constancy of the speed of light, time dilation, length contraction, etc.
But here's the thing: before the advent of relativity, humans were not used to very fast-moving objects. So we did not have a good grasp of how objects should behave at those speeds, or even the fact that the speed of these objects made any difference.
Interestingly, when we consider the expression for (special) relativistic momentum, we know that it's a good descriptor of the motion of objects moving at all speeds. And when we consider the motion of objects at speeds that we are used to in day-to-day life, we find that the special relativistic momentum expression actually reduces to the classical expression. In other words, at low velocities, classical and relativistic momentum looks the same! This is why classical physics derived the equation that p = mv (momentum = mass x velocity), rather than p = mv/sqrt(1-(v/c)^2), where c is the speed of light, taken to be a constant in relativity.
This kind of logic is used as a little test for many complicated theories by the way. If any theory is a complicated and counterintuitive one, we can ask the question. "does our theory reduce down to classical physics under the right conditions?". This is because in these specific conditions, classical physics is indeed a good description of the universe. So our weird new theory agreeing with this is only a good thing. If the two theories disagree, then this is not a huge problem - we need to try and work out why. When we apply this logic to quantum physics, a principle known as the Correspondence Principle pops up. In the limit of large quantum numbers, quantum systems must look like classical systems. In simplified terms, quantum mechanics describes very very small systems excellently. And this behaviour, when extended to much larger systems, must agree with the behaviour that we happen to observe - distinctly classical behaviour, which is why we came up with classical mechanics in the first place.
I also wanted to use a nice little analogy to represent our understanding of the universe from a classical perspective, and how subsequent mind-bending. "weird" theories encompassed classical physics and yet described even more of the universe. So I put in some trains!
Thanks for watching this video! If you enjoyed it, please do hit the thumbs up button and feel free to subscribe. Check out my second channel here: / @_parthmusic
Follow me on Instagram @parthvlogs. I'll see you soon!
Nice video! Also thank you for not defining a "relativistic mass". Drives me crazy when I see that.
Thank you my man :) haha gamma.m all the way
Oh hey andrew, you here too. Did you managed to get out of papa flamy's basement.
@@ParthGChannel yeah you should definitely make a dedicated video on misconceptions about relativistic mass... Many people here on RUclips use it as a so called "reason" as to why speed of light is the highest possible speed...
LOL don't forget, people have been erasing history for millennia my friend.
Relativistic mass is pedagogically unhelpful. Nobody is insisting on erasing anything.
Hey there !! Can you please come up with a video briefing about the STRING THEORY , I tried learning about it from various resources but couldn't understand...LoL
So happy I found you man! It takes someone who knows a lot about a subject to explain it in such a simple way. Trying to explain something to my friends takes me a while because I assume they know certain things. Now I just ask them to watch your videos! I wish you all the best!
Reading “Project Hail Mary” and had to pause to brush up on Relativistic Mechanics and came across your excellent discussion and helpful example. I love that there is a platform and audience for this type of content!
Thank you man , please keep the videos coming , lol I'm passing physics because of you, not only that ,for the first time , I'm actually understanding it
Waits every Tuesday for your video. They are always great
Thanks Aryan!
Love this. Insightful video Parth! Love the content
Ohh...my favorite bhaiya ( big brother)
Again a rocking video and on a very interesting topic....
After watching this now I can surely apply common sense while studying relativity... Thnx a lot.....pls make even more videos like this🙏
The analogy is actually a good one. Thanks
P.s. You're doing a great job. Keep it up 🤙🏾
Love your videos. Please keep them coming.
*Loved the analogy*
Great video as always
Parth G : Why Physics theories are Counterintuitive ?
Me : WTF is Counterintuitive ? 🤔🤔
LOL perhaps I should have used a better word there, sorry about that.
Counterintuitive = going against intuition, or our beliefs about how things "should" behave, in this particular instance :)
@@ParthGChannel oh tqsm 🤩 ... I was joking too
You are very sympathic and competent too.. Thank you for your work Path, I am on board :-)
Hey, nice video and analogy :). It helped put things into perspective.
Loved this video, was often curious of that sqrt(1 - v^2/c^2) because it seems to pop up in a few places, so thanks.
Wondering if you could do a video on the version of e=mc^2 that also includes the objects speed?
Hey Parth! Your videos are so cool and easy to grasp! Thanx for making these.
Just like me, many will appreciate if you would kindly make a video on Bose Einstein Condensate 🙏🙏🙏
I love these videos. Keep them coming.
Lol....good to know you read our comments. This analogy is spot on. Am having debates with some flat earthers. They keep giving 'facts' based on their reality, just as you have explained, "Train from work to office, not knowing how office to city operates". some would even argue city is cgi..lol.
Please make a video on General Relativity and its equation sir. Loved this Special Relativity video. Excellent job sir. I am a 12 year old boy from India and I totally love your videos and you are my role model. I am just another Physics aspirant.
Thx for da laix.
Mashallah, mashallah! I pray that you study well and become a very good scientist inshallah, study well my brother.
A 12 year boy watching these videos. Fantastic.
I genuinely want to thank you for this video :-)
Man you should make videos for graduate students too(like with using calculus and stuff) students will surely appreciate that.
BTW Really good work man.
You are very creative. Thanks for your clear explanation.
awesome video! I could not wrap my head around relativistic momentum
@Parth G Excellent analogy with the subset. Nice1
really dig this kind of video production
Thank you for making this video!
Keep doing what you do; it's great.
great video as always! hey I would like it if you'd consider making a video about time because it's hard for me to think of time as a dimension.
Hey parth! This video was awesome! I was wondering, could you do a video explaining how certain physics formulas came into being? I've always been curious about how physicists derived these formulas, and how they knew that they are correct. Like, how do we know the Force=mass x acceleration? How do we the know the gravitational potential energy of an object is equal to mgh? You get the idea, right?
Really hope you consider making a video/series on this stuff! Thanks!
Viradeus force is the derivative of momentum. which is p=mv. however momentum is just a definition created by newton to describe an objects motion. it gives us a way of comparing different moving bodies through laws of conservation and such. potential energy is also just another definition that allows us to compare the relative energies of different objects, also allowing us to complete laws of conservation of energy
Great explaination man! Keep it up 🙂
That Analogy was the best..
it just briefed the whole video
Please make a video covering Hawking's black hole mechanics math!!!
Sure! I'll add it to my list :)
Relativist's Toolkit: The Mathematics of Black-Hole Mechanics is a great book on black-hole math.
Trust me, I really need a good math way to understand them. And I am pretty sure, most of your viewers want that instead of just only simple explanation. 🙏🏻
Even though your name implies that you're a manchild, but you're right on this. The math is very important for a concrete understanding in my opinion.
@@user-lc6jq1hi1r
Your subjective opinions aren't held to be universal. Anyways, who asked?
I really liked the train analogy u made
great vid
thanks !
Great train analogy! 🚃
very well made video, enjoyed and learned a lot.😁😁
Your videos makes my to think and imagine in a brod way.
J John Paul broad*
Nice video i love those videos.🙂
Pleas if possible do a video about gravitationnal time dialation😁
Really good !!!
parth g i really like your videos i understan physics better than my professors at the school .....special relatvity is the hardest subject of physics displine ...but when i hear you i undesrstAND BETTER HAVE A GOOD SUMMER AND ALSO KISSES FROM CYPRUS WHICH IS A SMALL COUNTRY LIKE AN ISLAND IN THE EUROPE IN THE MIDDLE EAST OF THE Earth
Great video ♥! As a fellow RUclipsr, I am contantly searching for fresh ideas! Excellent Job!
Now I enjoy physics much more than i did before coz of u
Thanks Abhishek! :)
Your videos are epic!
Do a vid on general relativity and how it ties in with schwartzchild solution pleaseee
Very very very very good
Nice video. please make a video about interference of light. thanks🙏🙏🙏
Nice video ❤️❤️❤️
I have read lots of times in my books that Einstein's General Relativity tried to unify Gravity and Electromagnetism but was unsuccessful.
So, I read a book on relativity, but was unable to understand that why it is unsuccessful? 😅
Your video on this will help me and other people like me.
I would have loved this 2 weeks ago
so does this equation mean that it's impossible for any matter to move at the speed of light since the limit of its momentum as v approaches c is infinity?
Hi Parth
Just wondering if you could make videos on the concept of simple machines.
If you make a video on relativistic mass will be very helpful 😊😊
Awesome vid
Thanks :D
Parth.. kindly make video on navier stoke's equation...
Want to hear it from u dude...
Parth squad❤
Please make a video on thermodynamics
Hi Parth,
Thx to your videos. Very educational indeed.I have a question to you.. According to the equivalence principle,we know that acceleration and gravity are exactly the same or have the same effect. That is locally,in a small refgion of space. We know also that time is dilated NON-RECIPROCALLY in accelerated frames. Also,light bends in non-inertial frames. So,that should imply that locally in the fame,the spacetime curvature must be non-zero. There should be local spacetime curvature. I know,the Riemannian tensor is 0.. What do you think?
GENERAL RELATIVITY PLAYLIST FTW please :)
Thanks. Nice clear informative video.
Could it be that it be that relativity gives some additional insite?
I once saw something like this ;
E=m*c^2
=> E=(m0/ (1-v^2/c^2)^.5) *c^2
=> E=m0*c^2 + .5*m0*v^2 binomial expansion approximation for v
Hey Parth please make videos on basics of quantum mechanics.
Hi Parth
What would be a properties of a true void
A void where even fabric of space and time is not present.
Please reply
Well, a "true void" wouldn't have any properties because if it had properties it would be something and not nothing.
Plus, it doesn't really make any sense to think about nothing because we couldnt know what it'd look like.
Oh thanks for answering 😊
Nice bro
Please complete the Maxwell's equation playlist and if possible do videos explaining both integral and differential forms...
Videos talking about 4th Dimension Tesseract , although geometrically and conceptually correct ,you think violates the einstein 4D spacetime (max speed all directions is c, ds agreed by all relative moovers,.. ), or could be possible? As they move one 4D space object on time, they talk really in a 5D spacetime environment.
Can you make a video explain Kepler's Law of Planetary Motion for those with basic mathematical understanding.
Please do special and then general relativity too, with the maths if possible.
and if the speed of light is really a constant from all inertial frames.
I watched first video from your channel, wooho are you a Britisher your accent 😍😍😍😍
Awesome video as always!
Love ur hair style
What program do you use to edit your videos
I am self learner about relativity. Thanks for video. I am trying to understand geodesic. Can you please point to go websites for that? I couldn’t understand straight path on a curved surface.
Can you do one on relativistic mass?! Apparently relativistic mass increase was binned a while back for being unhelpful and confusing and we should speak of relativistic energy instead. An argument against mass increase is that to reach c you would gain infinite mass which would require infinite energy. That said, within your own reference frame you are not moving at all so in the same way you would not regard your length reducing or time slowing down, you would not measure your mass increasing and so you would not need infinite energy, as far as you are concerned. Could you also do the difference between gravitational mass, inertial mass, relativistic mass, transverse and longitudinal mass! There are lots of things I'd like to ask for as your explanations are really good!
So the energy of a moving body is also relative to the observer/frame of reference ? That is puzzling me... How does conservation of energy principle mix into that ?
Energy is conserved in every frame, it is not conserved between frames. This is equally true in special relativity, as it is in old-school Galilean relativity.
Which one has more gravity : Rest mass or relativistic mass? If relativistic mass, then how?
Please make a video on quantum field theory ❣️
I made it
At what speed or mass would you switch from classical to relativistic?
It's more like a "sliding scale" than a switch. The faster the object is moving, the less accurate classical momentum becomes. At that point, it's just a matter of the level of precision to which you are working, that will determine whether you need to consider relativistic momentum or not
This means there's always a common sense experience out there that can explain/model any phenomenon however bizarre it's , but waiting tobe discovered.
For me special relativity is a generalization of Newtonian mechanics. Am i correct or not??
I want to study astronomy but no university in the country where I live has this subject. How can I get a scholarship in the US or Canada to study there ?
Hard ro say. What country are you from if you do not mind me asking?
@@alexandertownsend3291 Bangladesh
Thanks parth g ( sorry i use a relative name to me 😁) about explaining until my brain get it :)
What is the exact temperature of fire 🔥
The red light in the background kinda looks like that black hole image :)
How about working of Sly wheel..... In simple terms?
Gotta love the Gedanken train...
Parth pleeease pleeease pleeease ampere's Maxwell's equations explanation as the final Maxwell video. I beg you
You and your hair are gorgeous, I love you man
Parth, I felt that this video was quite simple, like pretty much anyone can look at that 1-v^2/c^2 term and see what it reduces to for small v, didn't gain any valuable insight. Perhaps, a more interesting example would have been with General Relativity and Mercury's orbit.
I think he's getting there, but people have to explained why the universe has no explaining to do to them and that there is more to be discovered
Make video on quantum well
Plz brother use Hindi thus we and you #Grow.....btw you are very good teacher
statistics and entropy
Bro i am too parth g
Soo😅
Plzzz take my suggestion or just consider it as a request
Make a video on
"QUANTUM TELEPORTATION"
And what about light itself? Why does it have momentum?
Fourth!!!
I should say it......... U are damn cool
To path g: PLEASE PLEASE PLEASE GO SEARCH FOR RAYMONDO SWARTZ FROM SOUTH AFRICA!!!! he is a friend of mine and you guys look exactly the same!!!!! (well when your hair was short!!!) lmao
Nah not only physics it's literally the case with everything I study computer science and the most absurd and counterintuitive algorithms are the fastest ones lmao
Are you from India
The formulas: E=γm0·c², m=m0γ, p=m0γ·v are all wrong‼️
They all contradict Einstein's 1905 paper: "Does the inertia of a body depend on its energy content?" where Einstein finds that energy loss in terms of 'diminished mass' (transfer) is: L=∆E(rest)≈∆m·c².
He was right about the approximation for v 0/0~∆m(β=v/c→1)
=> You can use L'Hopital's rule wrt β.
Eventually, it can be shown that:
0=∆m(v→c), which simply means that a body doesn't emit energy or mass when traveling at c.
second
Hi :D
@@ParthGChannel hey parth
awesome video, i had one question.
what all new things did you learn at cambridge in your first year after a levels,
or was it just a revision of all topics?
Relativity is 100% intuitive. Spend a couple of minutes analyzing "Motion" to determine what exactly it is, and to also determine what it is that is required to make motion possible. Bingo, you will independently discover the Special Relativity(SR) phenomena, and you will also independently derive the SR mathematical equations, including the Lorentz transformation equations. No prior physics education is required. Just use common sense. If you passed grade 9, then you too can do it. The less you know, the easier it is to do, since you are not thrown of course by old theories.
Honestly, if you can figure out special relativity and derive the respective equations within a few minutes then you must be the greatest genius on earth.
3:25 Isn't that stemmed from Lorentz's transformation
Obviously
*anti gravity wheel.... 😊