B Layman's Question about Special Relativity

[phinds]

I just can't understand how different frames of reference can disagree on how much time has passed.

Although it will likely NOT be clear on first reading it, it will be very easily clear once you get into this stuff, that this is EXACTLY analogous to having one driver go from DC straight to NY and register one distance and another go by way of Chicago and the have a different odometer reading and they disagree on how many miles it takes to drive from DC to NY. It's an ANALOGY, so you have to ignore the fact that they can look at a map and see that the straight-line distance is not what either of them got but is something they can agree on. The analogy is just about their odometer readings, which are analogous to the clock readings on two different travelers at relativistic velocities. Different paths through space-time, from one event to another, can take different amounts of time.

 

[jbriggs444]

I'm mentally tapped out. It seems that I've turned my scenario into a version of the twin paradox and now we've moved into general relativity.

This is still pure special relativity.

 

[Grinkle]

This is still pure special relativity.

The post I referred him to may not be pure SR or it may be.

IMO, understanding the demarcation line between SR and GR is not required to understand the resolution to the twin paradox. Also IMO, understanding that demarcation is harder than understanding the resolution to the twin paradox.

 

[Nugatory]

IMO, understanding the demarcation line between SR and GR is not required to understand the resolution to the twin paradox. Also IMO, understanding that demarcation is harder than understanding the resolution to the twin paradox.

The easiest way of saying it: if there's a gravitating mass involved you need GR. Otherwise SR works just fine.

As a historical note, the twin paradox is introduced and explained as part of Einstein's first paper on SR, the 1905 "On the electrodynamics of moving bodies"

 

[Herman Trivilino]

Likewise, if I am driving down the highway at 50 mphs and a car in the opposite lane passes me and goes 60mph in the other direction, then by my measure, the other car is moving 110mph.

This is true, but be aware that if all you do is 50 plus 60 you're using an approximation. An extremely good approximation but nevertheless an approximation. The higher the speeds the poorer the approximation.

So your question is about why a low speed approximation won't work at high speeds.

 

[Aufbauwerk 2045]

I think it's excellent that you are interested, in spite of being a "layman" as you put it. Einstein wrote a famous book just for people like you. (Actually he was co-author. The book is the result of a collaboration with Leopold Infeld.)

https://www.amazon.com/dp/0671201565/?tag=pfamazon01-20

 

[Aufbauwerk 2045]

The two big theories to come out of 20th century physics are relativity and quantum theory. In addition to The Evolution of Physics by Einstein and Infeld, I strongly recommend this book by Gamow, since it is a great introduction to the development of quantum theory. Between these two books, you get a very good introduction to the physics breakthroughs of the early 20th century.

https://www.amazon.com/dp/048624895X/?tag=pfamazon01-20

 

[Peter Mole]

I think it's excellent that you are interested, in spite of being a "layman" as you put it. Einstein wrote a famous book just for people like you. (Actually he was co-author. The book is the result of a collaboration with Leopold Infeld.)

https://www.amazon.com/dp/0671201565/?tag=pfamazon01-20

Thanks, I've read a few and I'll check this one out when I get a chance. I don't know that I'm as interested in the other one you mentioned but I'll keep it in mind.

I've read all the comments here and I may check back from time to time, but I think I'm going back to my documentaries/lectures for a while.

Thanks to everyone not only for the information but for your patience in explaining (and re-explaining). :)

 

[PeroK]

I am in the same position as you. I am an engineer with training but I have NEVER seen an understandable explanation of special relativity. I think that most people (and perhaps all who attend this site) know the actual physics but have no real understanding of it and hence cannot give a layman's explanation.

Try, for example:

https://www.goodreads.com/book/show/6453378-special-relativity

 

[PeterDonis]

Moderator's note: Off topic posts deleted. The thread has run its course and is now closed.