Special Theory of Relativity

What is the Special Theory of Relativity? What were the motivations of Einstein to lay down his postulates?In this video, I do a brief summary of the history of Galilean invariance, Maxwell's Equations and how Albert Einstein connected all the dots to present his two posthulates.
The Special Theory of Relativity or STR is a ground breaking theory of Physics. It makes certain predictions about the nature of space and time that have far reaching consequences. To name a few: Length contraction, Time Dilation, Relativity of Simultaneity, Relativistic Mass, the famous E=MC^2 and so on
But how did all this come about?
I discuss all this in this video lecture.
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PLAYLIST ON Special Theory of Relativity
• Special Theory of Rela...
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1. History of Special Relativity ► • History of Special Rel...
2. Michelson Morley Experiment ► • Michelson Morley Exper...
3. Special Theory of Relativity ► • Special Theory of Rela...
4. Time Dilation (Thought Exp) ► • What is Time Dilation?...
5. Length Contraction (Thought Exp) ► • What is Length Contrac...
6. Lorentz Transormations ► • Derive Lorentz Transfo...
7. Relativity of Simultaneity ► • Relativity of Simultan...
8. Can you prove E=MC² ► • Can you PROVE the most...
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9. Special Theory of Relativity ► • Special Theory of Rela...
10. Length Contraction ► • Length Contraction (Sp...
11. Length Contraction of Inclined Rod ► • Length Contraction (& ...
12. Time Dilation ► • The Mind Bending Predi...
13. Muon Decay Experiment ► • The Mind-Blowing Proof...
14. Relativistic Velocity Transformations ► • Derivation of Relativi...
15. Speed of light in moving medium ► • Speed of Light in a mo...
16. Relativistic Doppler Effect ► • What is Relativistic D...
17. Relativistic Mass? ► • What is Relativistic m...
18. Relativistic Kinetic Energy ► • Relativistic Kinetic E...
19. Relativistic Force ► • Relativistic Force
20. Relativistic Energy & Momentum ► • Relativistic Energy an...
21. Magnetism arises from Relativity ► • The Hidden Connection ...
22. GATE Physics question ► • GATE Physics: Problem ...
23. TIFR Physics question ► • TIFR Physics: Problem ...
24. Question on Volume contraction ► • Volume Contraction in ...
25. JEST Physics question ► • JEST Physics: Solving ...
26. NET Physics question ► • CSIR-NET Physics Probl...
27. Spacetime Invariant Interval ► • SPACETIME Interval & i...
28. Minkowski Spacetime ► • Minkowski SPACETIME, H...
29. Eucledian Space & Minkowski Spacetime ► • 5 Main Differences b/w...
30. Spacetime Diagrams ► • Time Dilation, Length ...
31. Four Vectors in Relativity ► • What are FOUR VECTORS ...
32. Doppler Effect using 4-vectors ► • How to use 4 VECTORS t...
33. Compton Effect using 4-vectors ► • How to prove Compton e...
34. Particle Decay using 4-vectors ► • Particle Decay in Rela...
35. (SHORTS) Does Light experience time ► • Does light photon expe...
36. (SHORTS) Light for moving observer ► • What is the speed of L...
37. (SHORTS) Nothing can travel faster than light ► • Why nothing can travel...
38. (SHORTS) What is farther away ► • What is farther away, ...

[@FortheLoveofPhysics]

Time Dilation (Thought Experiment) ► kzbin.info/www/bejne/onPMcnhqgd2sbsk

[@prernabhardwaj486]

Thank you so much sir... For sharing your knowledge with us... This helps us to think beyond textbooks and the essence of physics. ❤❤🙂🙂

[@markomph]

I've watched many of your videos.Your work is grand!! Thank you!!

[@mostafaismail43]

I commend you for a great overview of a very tough subject.

[@jayasharma4208]

Good speaker

[@36-chilakalaprajitreddy9]

Superb sir, I am studying in 7th grade still I understood

[@rockgaming1440]

Then say what are maxwells equations?

[@abdullahshah3847]

Then tell me ...if we don't take the speed of light as a constant then what will happen. 😅

[@ericfunke]

Every time is watch one of your videos it adds some new aspect for me. A new way of looking at it. Thank you very much!

[@caltechharvard]

Wonderful. Thank you. I wish every curious mind viewed your videos. So enlightening.

[@saichaitanya7060]

sir please make a video on general relativity

[@brotherstech3901]

Beautifully explained as always!

[@ericfunke]

Thanks!

[@jeromehurst9297]

Many thanks for the video! I just noticed that there is a minus sign missing in the Faraday law

[@ugursoydan8187]

Can you make a video of derivation of relativistic mass? thank you

[@ponnamthirupathi8007]

Great teaching sir

[@FortheLoveofPhysics]

1. History of Special Relativity - Galilean Invariance & Maxwell's Equations : kzbin.info/www/bejne/hmichqVugbuWr5o 2. History of Special Relativity (Part 2) - Michelson Morley Experiment : kzbin.info/www/bejne/fIKqeIaEfrygadE

[@36-chilakalaprajitreddy9]

Sir, can you make video on general relativity and EINSTINE FIELD EQUATION

[@36-chilakalaprajitreddy9]

Please

[@michaelbrowne4525]

great speaker...keep it up bro

[@SymphonyKol_androidLover]

Really well made video bro keep it up.

[@FortheLoveofPhysics]

Thanks man :)

[@kingsleyibe-r8c]

Thank you for your great work. how can i collaborate with you for my postgraduate study

[@زينالعابدينماجد-خ1خ]

Thank you

[@AdhiNarayananYR]

Great video bro.

[@منوعات-ت6ف]

Is the length of stick is same with Newton ? Does newtons laws denies length contraction?

[@new-knowledge8040]

Start with an "Absolute" 4D environment. Let's call it, Space-Time. Now let us set any and all mass that is present within this 4D environment, into constant "Absolute" motion. The magnitude of this absolute motion, will be identical to the magnitude of motion of which light has as it moves across just space. Thus we have absolute ongoing motion that is taking place within an absolute environment. Now if you create a simple geometric representation of these absolutes, and do so by combining motion vectors and length scalars, you will soon see the cause behind Special Relativity(SR), and within mere minutes you can use this geometry to derive all of the SR mathematical equations, including the Lorentz Transformation equations. Thus, "Absolutes" do have value.

[@FortheLoveofPhysics]

+NEWKNOWLEDGE I agree with you. Absolutes do have value. However, what I was talking about in this video was the Newtonian idea of absolute distances and absolute time (separately). In relativity, space and time are not separately absolute (as in Newtonian Mech), but there are other quantities that are invariant/absolute if u want to call it. For eg the Space-Time Interval is invariant under Lorentz transformations in Minkowski space time. I have not talked about any of that in this video since I am trying to build these ideas as they came about historically from the perspective of a student who is only familiar with Classical physics. Ideas on four vectors and minkowski space come later.

[@new-knowledge8040]

Yes. I was specifically pointing out that absolutes should not be tossed out the window, which unfortunately many a folk do after misinterpreting videos such as yours. Here is another example. I have "Absolutely" no school physics education. But I found that If you know nothing about Galilean Transformations, Newton's Laws, and things like Maxwell''s Equations, then by a big surprise it turns out to be much much easier to discover Special Relativity(SR), and do so all by yourself, and also independently derive all of the SR equations, along with the Lorentz Transformation equations. All you have to do is analyze "MOTION". Check my YT videos if you have some spare time.

[@FortheLoveofPhysics]

+NEWKNOWLEDGE I don't think I agree with your characterization. I did not toss absolutes out of the window. I only made the statement that length and time are not absolute in relativity in the same manner it is in newtonian physics, which is very much true. They are not. You are talking about other absolutes i.e space-time interval. I don't think there is any room for misinterpretation.

[@new-knowledge8040]

I was not referring to you concerning the "Toss absolutes", but to others who as I have said are "misinterpreting videos such as yours.". As a matter of fact, I find your videos the best that I have seen yet.

[@FortheLoveofPhysics]

NEWKNOWLEDGE Okay. Thank you

[@williamwalker39]

The 2 premises of Special Relativity are just Galilean Relativity! Einstein's theory of Special Relativity is based on 2 premises 1) Galilean Relativity: the laws of physics are the same in all inertial frames of reference 2) the speed of light is the same in all inertial frames of reference. Taking the second derivative with respect to time of the Galilean Transformation yields acceleration is the same all frames. Since Force is proportional to acceleration, then Force is the same in all frames. Since Electric and Magnetic fields are proportional to Force, then Electric and Magnetic fields are the same in all frames. And since light is made of Electric and Magnetic fields, then light must be the same in all frames. So the 2nd premise is already included in the 1st premise. This is because the speed of light c is a law of physics, and according to the 1st premise it must be the same in all inertial frames of reference. Another way of stating the 1st postulate, is that there is no experiment that can be done to determine the speed of an inertial moving body. So the 2nd postulate must be included in the 1st postulate, otherwise one could do an experiment based on the speed of light to determine the velocity of a moving inertial observer (like the Michelson Morley experiment). The 1st postulate predicts the Michelson Morley experimental outcome! So why was the Michelson Morley experiment even done? And why were they given the Nobel prize for the experiment? Probably, and rightly so, for developing the Michelson interferometer, which has had a huge impact on the sensitivity of measurement sensors. So if the 2 premises of Special Relativity are just the premise of Galilean Relativity, then according to logic, it is impossible to get different transformations (Lorentz transformations) than one gets for Galilean Relativity (Galilean transformations). Consequently Galilean Relativity must be the correct theory of Relativity. So if the effects of Relativity are observed in experiments, then the effects of Relativity must be an optical illusion.

[@kimsahl8555]

Well, the laws of the nature is not equal about a system at rest vs a system in motion.

[@shivamaryajha1783]

How do postulates of str imply that galilean transformations are wrong? Pls Answer asap...

[@FortheLoveofPhysics]

1st posthulate claims that all physical laws (including Maxwell's laws) are invariant under a transformation from one inertial frame of reference to another. This isn't true for Galilean transformation of Maxwell's equations. I have proved it in my first video on history of str. You can check that.. kzbin.info/www/bejne/hmichqVugbuWr5o 2) STR puts speed of light as a constant in all inertial frames. Galilean transformation cannot account for that.

[@alipillai7752]

Very lovable

[@Motivation-h3e]

❤️❤️❤️

[@fabriziosantin6063]

NIce videos, but please, beware of the idea of "relativistic mass". There's only one mass, rest mass.

[@zaibkhan7039]

Sir can you speak urdu.their are some difficulties in understanding English quickly

[@adrianferent3584]

“Einstein’s Special Relativity and Einstein’s General Relativity are old and wrong theories” Adrian Ferent “Special Relativity is wrong at Quantum level, time contraction not time dilation” Adrian Ferent

[@williamwalker39]

Relativity is just an optical illusion, and because all of modern physics is based on Relativity, modern physics is fundamentally wrong and needs to be rethought. Relativity has a simple built in logical fallacy, and no theory based on a logical fallacy can be true, no matter how many experiments seem to prove it, or how many people say it is true. Below is a very simple logical argument highlighting the logical fallacy, using the same terminology Einstein used to derive Relativity. According to Relativity, observers on a moving train and on a stationary train platform will disagree on the size of the ""Train"" and the passage of time on the ""Train"". This is a complete logical contradiction if the size and the passage of time of the train are real. If the size of the train is real, then the ""Train"" can not be both contracted and not contracted. The same goes for the observed passage of time on the ""Train"". If these effects are observed, then the only possible conclusion is that it is an optical illusion. Things that are real must appear to be same from all frames of reference. If not, then by definition it is an illusion. Again the argument is very simple and it is the argument Einstein used to derive Relativity, and no acceleration is used in the argument. A train with length (L) traveling at constant velocity (v) relative a stationary observer on a station platform. According to Relativity, the stationary observer will see the train contracted (L/r, where r is the Relativistic gamma), whereas an observer on the train will see it not contracted (L). So the train is both contracted (L/r) and not contracted (L) depending on the observer. This is a complete contradiction (L not equal L/r) and can not be true if length is real. The same argument applies to passage of time on the Train, where both observers will disagree on the passage of time. If time is real, it can not be both dilated and not dilated (T not equal rT). If space and time are observed to be both large and small simultaneously for one inertial reference frame, such as the ""Train"", then it must be an optical illusion. This argument is only the tip of the iceberg. There is much more evidence including both theoretical and experimental, so please keep reading. Hi my name is Dr William Walker and I am a PhD physicist and have been investigating this topic for 30 years. It has been known since the late 1700s by Simone LaPlace that nearfield Gravity is instantaneous by analyzing the stability of the orbits of the planets about the sun. This is actually predicted by General Relativity by analyzing the propagating fields generated by an oscillating mass. In addition, General Relativity predicts that in the farfield Gravity propagates at the speed of light. The farfield speed of gravity was recently confirmed by LIGO. Recently it has been shown that light behaves in the same way by using Maxwell's equations to analyze the propagating fields generated my an oscillating charge. For more information search: William Walker Superluminal. This was experimentally confirmed by measuring radio waves propagating between 2 antennas and separating the antennas from the nearfield to the farfield, which occurs about 1 wavelength from the source. This behavior of gravity and light occurs not only for the phase and group speed, but also the information speed. This instantaneous nature of light and gravity near the source has been kept from the public and is not commonly known. The reason is that it shows that both Special Relativity and General Relativity are wrong! It can be easily shown that Instantaneous nearfield light yields Galilean Relativity and farfield light yields Einstein Relativity. This is because in the nearfield, gamma=1since c= infinity, and in the farfield, gamma= the Relativistic gamma since c= farfield speed of light. Since time and space are real, they can not depend on the frequency of light used. This is because c=wavelength x frequency, and 1 wavelength = c/frequency defines the nearfield from the farfield. Consequently Relativity is an optical illusion. Objects moving near the speed of light appear to contract in length and time appears to slow down, but it is just what you see using farfield light. Using nearfield light you will see that the object has not contracted and time has not changed. For more information: Search William Walker Relativity. Since General Relativity is based on Special Relativity, General Relativity must also be an optical illusion. Spacetime is flat and gravity must be a propagating field. Researchers have shown that in the weak field limit, which is what we only observe, General Relativity reduces to Gravitoelectromagnetism, which shows gravity can be modeled as 4 Maxwell equations similar in form to those for electromagnetic fields, yielding Electric and Magnetic components of gravity. This theory explains all gravitational effects as well as the instantaneous nearfield and speed of light farfield propagating fields. So gravity is a propagating field that can finally be quantized enabling the unification of gravity and quantum mechanics. The current interpretation of quantum mechanics makes no sense, involving particles that are not real until measured, and in a fuzzy superposition of states. On the other hand, the Pilot Wave interpretation of Quantum Mechanics makes makes much more sense, which says particles are always real with real positions and velocities. The particles also interact with an energetic quantum field that permeates all of space, forming a pilot wave that guides the particle. This simpler deterministic explanation explains all known quantum phenomena. The only problem is that the Pilot Wave is known to interact instantaneously with all other particles, and this is completely incompatible with Relativity, but is compatible with Galilean Relativity. But because of the evidence presented here, this is no longer a problem, and elevates the Pilot Interpretation to our best explanation of Quantum Mechanics. *KZbin presentation of above argument: kzbin.info/www/bejne/qZazlX1tq7iErLM *Paper it is based on: William D. Walker and Dag Stranneby, A New Interpretation of Relativity, 2023: vixra.org/abs/2309.0145