Chapter 9

Squeezing and Stretching Reality
(Special Relativity)

“Light in empty space is always propagated
with a determinate speed V, 
which is independent of the
state of the emitting body.”
~ Albert Einstein

Author’s note:
The speed of light, which Einstein calls “V” in the above quote, is
represented these days with a lowercase “c” — as in the formula E=mc2.
This lowercase “c” stands for “celeritas” which is the Latin word for “speed.”

Your Reality Depends on Your Velocity
Relative to the Object You Are Observing

From ancient times up through the scientific revolution (from Euclid to Newton), most scientists and philosophers considered space to be a fixed background across which objects moved. The movement of (and changes to) objects could be tracked by the universal nature of time. If one second ticks by for me, that same second ticks by for you. And that very same second ticks by everywhere in the universe, instantly.

Now, obviously, at our human scale of existence, the ideas of space as a fixed background and of time as being universal work quite well. Good enough for daily life. But when the relative velocity between the observer and the subject being observed gets close to the speed of light, the real world is no longer fixed and universal. Time gets stretched. Time in your frame of reference runs differently than time in the frame of reference of the subject being observed. Also, the subject’s space gets squeezed in its direction of travel. That sounds ridiculous, but experimental results bear it out.

You and I will never notice these effects — unless you work at a particle accelerator, observe light a little too closely (as in the Michelson-Morley experiment), study cosmic ray muon decay, or start flying atomic clocks around the world. So for everyday life, Newtonian physics works just fine. But it’s not how the universe really works. Not when there is a large or long-term relative velocity between you and what you are observing. Especially if that velocity approaches the speed of light.

So check out this chapter for the story of how “relativity” unfolded from Galileo to Einstein. And why is time a location? And is the speed of light peculiar to light, or is it some fundamental attribute of our universe?

I could not figure out any you-can-do-this-at-home activity for this chapter. Most of us do not have a particle accelerator or a muon detector sitting around the house.

However! There’s a great brain-teaser related to special relativity, called “The Twins Paradox.” I invite you to watch the two videos by very talented folks that I’ve linked below to explore this apparent paradox in special relativity:


The Twins Paradox

TED-Ed presentation by Amber Stuver:
https://www.youtube.com/watch?v=h8GqaAp3cGs

Henry Reich at the Minute Physics channel:
https://www.youtube.com/watch?v=0iJZ_QGMLD0


Here are the links from the text in Chapter 9:

53. Biography “Albert Einstein – Wikipedia.” 
https://en.wikipedia.org/wiki/Albert_Einstein

54. Deeper Dive “Einstein’s Theory of Special Relativity | Space.” 30 Mar. 2017,
https://www.space.com/36273-theory-special-relativity.html

55. Biography “Bernhard Riemann | | Britannica.” 
https://www.britannica.com/biography/Bernhard-Riemann

56. Biography “Hermann Minkowski | German mathematician – Encyclopedia ….” 8 Jan. 2022, 
https://www.britannica.com/biography/Hermann-Minkowski

57. Deeper Dive “Annus Mirabilis papers – Wikipedia.” 
https://en.wikipedia.org/wiki/Annus_Mirabilis_papers

58. Deeper Dive “Fission vs. Fusion – What’s the Difference?” 30 Jan. 2013,
https://nuclear.duke-energy.com/2013/01/30/fission-vs-fusion-whats-the-difference

59. Great Video “What Is Brownian Motion? | Properties of Matter YouTube.” 30 May. 2013, 
https://www.youtube.com/watch?v=4m5JnJBq2AU
Warning: Starts with ads.

60. Deeper Dive/Physics-Speak “Galilean invariance – Wikipedia.” 
https://en.wikipedia.org/wiki/Galilean_invariance

61. Deeper Dive/Physics-Speak “Inertial frame of reference – Wikipedia.”
https://en.wikipedia.org/wiki/Inertial_frame_of_reference

62. Deeper Dive “Galileo’s ship – Wikipedia.” 
https://en.wikipedia.org/wiki/Galileo%27s_ship

63. Deeper Dive/Physics-Speak “Relativity : the Special and General Theory by Albert Einstein.” 7 Jan. 2022,
http://www.gutenberg.org/ebooks/5001

64. Great Video “We are all moving at the speed of light – YouTube.” 20 May. 2019,
https://www.youtube.com/watch?v=k73psdcmzEY
Warning: Starts with ads.

65. Deeper Dive “Does light experience time? – Phys.org.” 8 May. 2014,
https://phys.org/news/2014-05-does-light-experience-time.html

66.  “Impossible Muons – YouTube.” 13 Nov. 2018,
https://www.youtube.com/watch?v=rVzDP8SMhPo
Warning: Starts with ads.

67. Deeper Dive “De Sitter double star experiment – Wikipedia.”
https://en.wikipedia.org/wiki/De_Sitter_double_star_experiment

68. Deeper Dive/Physics-Speak “Kennedy–Thorndike experiment – Wikipedia.”
https://en.wikipedia.org/wiki/Kennedy%E2%80%93Thorndike_experiment

69. Deeper Dive “Hafele–Keating experiment – Wikipedia.”
https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment

70. Great Video “Are warp drives science now? – YouTube.” 15 Jan. 2022,
https://www.youtube.com/watch?v=YdVIBlyiyBA