POSTULATES of Special Relativity and Inertial Frames
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- เผยแพร่เมื่อ 23 ก.ค. 2022
- This video is about the very core of special relativity because I am talking about the postulates of special relativity in a more detailed manner but I also make a clear definition of an inertial frame of reference so we are on the same track when deriving complicated phenomena in special relativity.
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First: I enjoy watching your videos, it feels like a good addition to the stuff I already watch (dialect, spacetime, etc you know them all..)
It seems to me, the time when there arises a 'paradox' or a conflict of theories is always when a real process is being abstracted to a kind of thought experiment, or shortened to a concept, a description of the actual reality.
Yes, the grenade explosion may kill the person, even if separated in distance. But it doesn't do that by magic, there's a pressure wave, or maybe shrapnel, that is actually covering the real spacetime distance between grenade and person before the person will die.
So in a frame of reference that is going at enough of a relative speed and appropriate direction in order to see the person die first and the grenade to explode second, what happens in between? Does the shrapnel fly back to the grenade after killing the person? Wouldn't the grenade kind of have to explode in reverse?
In our understanding of single direction time, relativity may reach its limits at this thought. Simultaneity being relative and all, you explained the concept for example with the ladder paradox.
I'm thinking that relativity is not the end of the story at this point. Our experience and expectations of entropy are one thing, but when you think the physical reality through, there are unanswered questions
Thank you for that excellent explanation. So, if I understand correctly, the disconnect between relativity and quantum theory is that paired particles violate the fist postulate?
Hi, the quantum theory and special relativity can be reconciled together it is called quantum field theory. The problem is to reconcile it with general relativity as such theory has inremovable infinities (it can't be renormalized). Another issue is that quantum theory is linear whereas general relativity is non-linear theory.
Nice video
Thanks alot
my pleasure!
Time is absolute in relativity (the length along a world-line, Δτ), it's the Newtonian world-time that is not absolute, Δt.
Nice video, thanks.
I have a question about simultaneity: suppose two events A and B are simultaneous in one frame F while they are not simultaneous in another frame F_1. This means that in the frame F_1 event A occurs before event B (or vice versa)
If event A occurs earlier in frame F_1, then this means that in frame F_1 event B has no choice. (event B must necessarily happen because we know that event B happens in frame F)
My question is:
IN THIS CASE IT IS HOW PREDICT THE FUTURE ?
This seems strange to me, surely causality is not violated but it is strange that an event is bound to happen.
Event B may very well be represented by a man committing a mortal sin.
In frame F_1 that man is about to be sentenced to Hell and has no chance to change his mind.
I think Lorentz transformations are correct (and I'm not a religious fanatic) but Free Will is the Free Will.
Perhaps the two events A and B are truly simultaneous in frame F (and may or may not happen), but in the other frames the time difference between the two events A and B is only apparent.
And in my opinion it is not nice to know that some events in the frame of the Earth must necessarily happen, just because these events have already happened in other frames.
I obviously understand that my consideration is PURELY PHILOSOPHICAL ... :)
Hi Massimiliano. First of all, I just want to say I wasn't trying to explain the relativity of simultaneity in this video so the animations here were just for some intuition but in reality, you need a relative motion the next video is gonna be about the relativity of simultaneity actually.
Anyway, about your question. The problem is that even though the observer in frame F sees two events happening simultaneously, there is no way he can send this information to another observer who doesn't see this simultaneously in time because there is not a causal connection between the observer F_1 and F. But even if he had that information, there is no way he could influence those events because he is also causally disconnected to them.
About your example of a man committing a mortal sin.
committing a mortal sin is an experiment on its own and if someone does that then it must happen in every reference frame.
If you want to talk about causality you must have two events that are separated by some distance and then you can talk about the relativity of simultaneity.
If you have two men committing a mortal sin then the question is whether the action of one could influence the decision of the other.
If you somehow managed to send information faster than light, then you run into a problems with causality and that is the singularity of special relativity. Special relativity forbids any faster than light traveling and if there was something that is traveling faster than light then we need a better theory.
@@lukasrafajpps " The problem is that even though the observer in frame F sees two events happening simultaneously, there is no way he can send this information to another observer who doesn't see this simultaneously in time because there is not a causal connection between the observer F_1 and F. But even if he had that information, there is no way he could influence those events because he is also causally disconnected to them."
Yes, this is true.
" Special relativity forbids any faster than light traveling and if there was something that is traveling faster than light then we need a better theory."
I am satisfied with Special Relativity, the second postulate is beautiful as it is ... :)
I always find this so facinating how many weird phenomena we got just from this one postulate :) and even more interesting is the fact that every phenomena is a direct sonsequence of this postulate derived by pure logic so as long as this postulate holds special relativity must hold :)
Next video about relativity of simultaneity is gonna demonstrate that.
@@massimilianodellaguzzo8571 You surely give pretty hard questions to answer 😀
@@rene6393 I think Lukas is very good, so it's a pleasure for me to ask him these questions.
I think you are both correct and bold You should visit his museum in Bern. Go show and God Speed as God doesn't roll (play) dice. Language definitions of words especially in language analysis philosophy is the most important area we have to know what we're saying and we have to know what we're talking about.... You can find a paper in Einstein's Museum the hero with Bertrand Russell who you should read and they wrote a paper together against nuclear weapons. I have an undergraduate degree in philosophy a science Master's and doctorate in law but I've also self-taught myself data science etc so it's very important that you remember the basis of all learning is indeed philosophy what is a PhD called?
If the rocket was traveling at 50% the speed of light and turned on his light beam, he would measure his light beam as moving away from him at 100% the speed of light. My question is since time dialation is only 15% at that speed it doesn't make sense to me. If time dialatiin was 50% at that speed then it would make sense that he measures light at 100% the speed of light.
Well, this is just a math problem. SR isn't linear in this nature. You can look at the velocity addition formula in SR that has been derived purely on the postulates of SR and it all adds up nicely.
concratulations you now relise that you exist within a programmed vertual reality
Not trying to be disrespectful but physics/science is not descriptions…
We might have different descriptions for the same thing in physics. For example Newtonian mechanics, Lagrangian mechanics, Hamiltonian mechanics but it is just a word game should I call it different description of the same thing or different theories for the same thing? I honestly don't know which should be correct.
@@lukasrafajpps thank you for the response 🍻
@@lukasrafajpps Isn't it fair to say that Newtonian, Lagrangian and Hamiltonian Mechanics are each a mathematical description' of their own particular model of mechanics in Physics? The descriptive language of Physics/Science is Mathematics one could say, hence 'descriptions' are a fundamental part of Physics/Science.
Physic: objects that exist and the mechanisms.
What is a object
What is space
What is exist.
First three words we need defined in any presentation, other wise as you say it’s religion.
A frame in what?
Space/time…
In this case I would have to start with the whole oxford dictionary but that is available for everyone.
@@lukasrafajpps In physic we wanna explain a mechanism to a phenomenon. This is why the three words are so Important. With these three words we can class all words of the dictionary into two Categories one being nouns objects which I’ll have shape and everything else being concepts they must be defined.
So when I bring up a subject like wave what is it that’s waving a wave is a concept not an object something must do the waving. Another big problem with a lot of assumptions is reifying concepts saying a energy is the something space-time is a something
I don’t intend to offend but I do love these conversations of physics and physics are objects that exist because if we don’t have something to talk about then what are we talking about.
I’m open to continue the conversation I have two kids and a wife so my time is limited and I’ll try to respond as wholeheartedly as I can
But this can easily go out of hand because when we are using a language then one might the definition of other words as well and we can go indefinitely therefore I want to define just words that are not used in everyday conversations like inertial frame of reference.
It can also go very philosofical for example the question what is exist? it is just a philosofical question and there we can argue about the proper definition but for special relativity I don't need any deep definition of these words because it is a simple theory.
The definition of space might be important more but in special relativity, space is something where you can measure distances.
Object is just a thing of arbitrary shape that exist and its shape is depicted in the animation.
spacetime and energy on the other hand is kinda nontrivial and it needs to be defined. I wasn't talking about spacetime yet but I am going to but esentially you can measure not only distances but also time.
Enargy is very nontrivial because the definition lies in Emmy Noether's theorem. Energy is a quantity that is conserved under a continuous time transformation symmetry and its mathematical definition is through Lagrangian where you require that time shift in lagrangian leads to the same equations of motion.
yes and waves can be thought of as a periodic oscilation of a field for example light is a periodic oscilation of electromagnetic field