Oral Exam: Physics: Principle of relativity

[Eivind]

So for my oral exam I have to make a 15min presentation about the principle of relativity. What points do you think it's important to include seeing as I only have 15 minutes?

So far, I'm planning to talk about:
- Referance systems
- How time and length gets effected by moving with ~speed of light[Lorentzfactor]
- How the formulas for force, etc etc works in the special priciple of relativity.
- The general priciple of relativity(time, gravitational forces and bending of light)

Note: All terms are directly translated from norwegian, if something sounds funny, let me know. Also, this needs to be done by the 10th of june.

[IlPrincipeBrutto]

Who is your target audience, and what is the purpose of the talk ?

Edit: silly me, I can see from the title it's an exam. And it's also in the very first line of your post. me = silly squared, which chimes nicely with the subject :-)

Given that I made a fool of myself, allow me to be a pedant too: the author spoke about the Theory of Relativity, not the Principle.

Also, the gravitational forces come into play in the General Theory of Relativity, but not in the Special one. Does your talk need to be about both ?

IPB

[Eivind]

It is indeed the theory of relativity. And I have to talk about both, but the main focus is on the special theory. My teacher said that I'd simply have to mention a few words about what defines the general theory instead of going in-depth on it.

Also, I didn't mean to imply that gravitational forces come into play in the special theory either. I'm not too shabby on the subject, but I'm fairly uncertain on how to present everything, as well as what to include.

New idea for the presentation:
− Lengthening of time
− Contraction of length
− The twin paradox(one twin stays on earth, the other travels in a space rocket travelling near the speed of light)
− Events that happen at the same time, but different referance systems = different experiences of the event.[no idea what the english term for this is]
− Momentum of fast electrons

EDIT: My audience is just my teacher and an examinator who's just there to double-check that everything follows standard procedure, as well as assisting in setting the grade. So basically, two adults who know more about physics than I'm able to imagine.

[IlPrincipeBrutto]

Have you thought about presenting the theory in an historical context ? you could show first what was the state of the knowledge at the time, and how it was not in accord with some experimental evidence (ether, Michelson-Morley).
Then you introduce the Special Theory, and show how it solved the problems and represented a natural evolutionary step from newtonian mechanics.

In this way, Einstein's work is set into context, and its importance can be appreciated fully.

From there, is a short step to the generalisation of the General Theory, if you need to include that too.

IPB

[Eivind]

Have you thought about presenting the theory in an historical context ? you could show first what was the state of the knowledge at the time, and how it was not in accord with some experimental evidence (ether, Michelson-Morley).
Then you introduce the Special Theory, and show how it solved the problems and represented a natural evolutionary step from newtonian mechanics.

In this way, Einstein's work is set into context, and its importance can be appreciated fully.

From there, is a short step to the generalisation of the General Theory, if you need to include that too.

IPB
That sounds like a pretty good idea! I'll ask my teacher if she'd prefer a more fact based or an historical based presentation, or a mix of the both.
Either way, I'll probably be able to use some of your ideas. Thanks a lot, IPB!

[IlPrincipeBrutto]

Thanks a lot, IPB!

You are welcome.

IPB

[NolanPower]

The principle that light always travels at the speed of light in any reference frame.

[Gary Gibson]

The principle that light always travels at the speed of light in any reference frame.

Which is why lengths have to contract, mass has to increase and times have to dilate as speed increases. The effect happens at lower velocities, but gets more pronounced as you approach light speed.

How fast do I have to go relative to you fuckers to get into the 100 kg class?

[pwn]

Perhaps you could show this video, "the complexity of fluid dynamics in slow motion." (http://www.youtube.com/watch?v=dp6lWVDvlTY)

[dmd]

I think you should discuss the following effect, which must be relativistic in nature:

No matter how early I get up in the morning, I am still 10 minutes late getting to work.

[Patrick]

You absolutely MUST talk about the invariance in the speed of light. Special relativity is nothing but that. Sprinkle in whatever ever you want around it, but if you can derive the gamma factor from a diagram then you'll get a perfect score. General relativity is the hardest thing I ever learned. I mean, it's really fucking hard. My best advice is not to get too fancy in terms of what you think you know about it and just discuss the idea of a curved manifold giving the equations of gravity. If you'd like to delve a little bit, talk about how GR explains black holes (infinite curvature past the Schwarzschild radius).

[Eivind]

I think you should discuss the following effect, which must be relativistic in nature:

No matter how early I get up in the morning, I am still 10 minutes late getting to work.
I'll start the presentation off with this quote, seeing as someone who is pretty much failing the class is going to go right before me, I have to lighten the mood a little.

Or, I'll start off by saying "this was a RELATIVELY easy subject....." or some crappy pun like that.



You absolutely MUST talk about the invariance in the speed of light. Special relativity is nothing but that. Sprinkle in whatever ever you want around it, but if you can derive the gamma factor from a diagram then you'll get a perfect score. General relativity is the hardest thing I ever learned. I mean, it's really fucking hard. My best advice is not to get too fancy in terms of what you think you know about it and just discuss the idea of a curved manifold giving the equations of gravity. If you'd like to delve a little bit, talk about how GR explains black holes (infinite curvature past the Schwarzschild radius).
Good thing I don't have to say much about the general theory then, but I'll be sure to touch the subject very lightly and avoid using difficult terms. As long as I get the main idea(accelerated referance systems are the same as gravitational fields, the laws of physics have the same form in all referance systems)) from the course I'm taking.

And when you mean derive the gamma factor from a diagram, do you mean using geometrical figures?

[Jamie J. Skibicki]

Gravity waves and the problem with instaneous force at a distance is part of general relativety, right? It's been a while and I really didn't get into it much, I prefered mechanics and math.

[msingh]

A lot of guys are suggesting talking about lorentz transform, and I agree, but where does gamma come from? The origin is in the work of Poincare who derived an invariant transformation of Maxwell's Field Equations. So if i were you, i'd follow that tack of thought. Then it's an identity to show the speed of light is the same in inertial reference frames.

[msingh]

The principle that light always travels at the speed of light in any reference frame.

Not any reference frame, in all inertial or non-accelerating ones..

[imnotbncre8ive]

I haven't studied general relativity, so I can only comment on special relativity. But if this presentation is meant to be a very introductory one, then I think IPB's suggestion of a historical approach is a good one. Then perhaps derive a few of the kinematic implications (since they're the simplest): time dilation, loss of simultaneity, length contraction, invariant interval. Good luck.


Not any reference frame, in all noninertial or non-accelerating ones..

I think you mean inertial frames?