The Big Bang & A Couple of Paradoxes

What is the Big Bang Theory?

The point from which it all began. An explosion some 14 billion years ago that gave birth to the universe. 

Not unlike Charles Darwin looking over his collection of specimens and finding himself unable to deny that species weren't entities fixed in space and time, so too is it the case with the Big Bang. Yes, both have gaps to fill. But they also present us with observations warranting continued investigation, as the applications and extrapolations of both theories have very tangible effects on our present day world.

Observations supporting the proposed Big Bang model:

1.) The expanding universe: In the 1920’s Edwin Hubble observed that most galaxies were moving away from our own. That light was taking longer to reach us than it would in a non-expanding universe.


2.) The detection in 1965 by Arno Penzias and Robert Wilson who, using a radio receiver, picked up the signal of cosmic microwave background radiation. In essence, photon shrapnel left over from a very big and hot explosion.


3.) That the predicted proportion of elements generated from such an explosion have been observed in slow-burning stars and primitive gas clouds in our galaxy.
(Source for above: Joanne Baker's, 50 physics ideas you really need to know; pages 180-183.)




What is Einstein’s Theory of Special Relativity?

Well, all I can say is that I'll give it my best shot. 

And for anyone wondering about the practical application of this theory, think GPS.

Okay so Relativity. How about we start with a question:

Have you ever been seated on a train, opposite another train, and then that train suddenly pulls out and you get the sense you’re moving?

Yes?

Well, that's relativity.

Done.

Though unfortunately not quite. Perhaps I should elaborate.



Consider the following 5 points:

Event B is simultaneous with A in the green reference frame, but it
occurs before A in the blue frame, and occurs after A in the red frame.

1) If you have two objects, and nothing else, then it would be impossible to tell which object is moving and which object is standing still.

2) The speed of light is a constant and appears the same to all observers.

3) Nothing can travel faster than the speed of light.

4) If the speed of light does not change and yet we observe a change, then well, something must be changing right? Or else we would view things as they were instead of how they appear relative to our position.

5) So, if speed = distance/time, and if, in the case of the speed of light we know the value is a constant (c), then Einstein proposed that what in fact is changing or ‘distorting’ is both distance and time: that as we approach the speed of light, these values compensate by shrinking and slowing respectively in order to keep the value of the speed of light constant.
(Source  for above, 50 physics ideas you really need to know; by Joanne Baker; page 160-163)




MinutePhysics via YouTube


And how does this relate to E=mc² ?




MinutePhysics via YouTube



Nothing complicated about that, right? 

So, just what is the Grandfather Paradox anyway?


Think Marty McFly's dilemma in the Back to the Future films.

Or, more accurately, the grandfather paradox can be described as follows:

• The time traveler goes back in time and kills his grandfather before his grandfather meets his grandmother. And as a result, the time traveler is never born. But, if he was never born then he couldn't have traveled through time to kill his grandfather in the first place. And if his grandfather was never killed, he would have met his grandmother and the traveler would be born after all, and so on.  (Source: Wikipedia) 

Check out the link: Time Travel Simulation Resolves “Grandfather Paradox” 

Two theories are discussed involving photons being transported back in time to kill themselves. One is based on probabilities. Apparently, with 50:50 odds of killing gramps, it becomes less of a paradox statistically. And in the other, each time the photon tries to deliberately kill itself, quantum fluctuation prevents it from happening.





And since we are on the topic of paradoxes ...

Marian and Vivian Brown, identical twins

"In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more.

This result appears puzzling because each twin sees the other twin as moving, and so, each should paradoxically find the other to have aged more slowly.

However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey, and so there is no symmetry between the space-time paths of the two twins. Therefore the twin paradox is not a paradox in the sense of a logical contradiction."(Source: Wikipedia)

Update / Related:

8 Ways You Can See Einstein's Theory of Relativity in Real Life / LiveScience / November 26, 2014
What if you traveled faster than the speed of light / How Stuff Works

Einstein's Theory of General Relativity / Space.com / April 10, 2015.

Relativity's Long Strong of Successful Predictions / discovermagazine.com / April 2015






References:

http://physicscentral.com/explore/writers/will.cfm
https://www.youtube.com/watch?v=ev9zrt__lec
https://www.youtube.com/watch?v=-Ip5BAEfZuA&feature=em-share_video_user
http://en.wikipedia.org/wiki/Grandfather_paradox
http://en.wikipedia.org/wiki/Twin_paradox
http://www.santafenewmexican.com/news/local_news/grab-your-flux-capacitor-scientist-talks-time-travel/article_457d7d51-4cb2-529a-bc4a-5f01be30154f.html
Baker, Joanne; (2007) 50 physics ideas you really need to know. Quercus Publishing: pages 160-163 & 180-183

Juan, Dr. Stephen; (2004) The Odd Body. HarperCollins Publishing: page 165-166.

Photo/Image Credit:

"History of the Universe" by Yinweichen - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:History_of_the_Universe.svg#mediaviewer/File:History_of_the_Universe.svg

"Relativity of Simultaneity" by created the original PNG file; Acdx converted it to SVG. - Derivative work of en:Image:Relativity_of_simultaneity_(color).png. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Relativity_of_Simultaneity.svg#mediaviewer/File:Relativity_of_Simultaneity.svg

"Marian and Vivian Brown" by Christopher Michel - https://www.flickr.com/photos/cmichel67/14146231281/. Licensed under Creative Commons Attribution 2.0 via Wikimedia Commons http://commons.wikimedia.org/wiki/File:Marian_and_Vivian_Brown.jpg#mediaviewer/File:Marian_and_Vivian_Brown.jpg