100 Years Later, Einstein’s Theory Tested by Satellites

SCIENCE

It’s a total fluke. No one was thinking about making the most precise test yet of general relativity when the European Space Agency sent a pair of satellites into orbit last year. But a botched launch put them in perfect position to test Einstein’s century-old theory. (Guardian)

Use our resources to learn a little about the man behind general relativity.

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit, including today’s 5-Question Quick Quiz on general relativity.

This illustration shows the off-kilter orbital paths of the Galileo 5 and Galileo 6 satellites. (The green orbital path is the ideal one, being followed by the first four Galileos as we speak.) The slightly elliptical orbit puts the new satellites in an unintentionally perfect position to do the world’s most precise tests of Einstein’s general theory of relativity. Illustration courtesy European Space Agency

This illustration shows the off-kilter orbital paths of the Galileo 5 and Galileo 6 satellites. (The green orbital path is the ideal one, being followed by the first four Galileos as we speak.) The slightly elliptical orbit puts the new satellites in an unintentionally perfect position to do the world’s most precise tests of Einstein’s general theory of relativity.
Illustration courtesy European Space Agency

Discussion Ideas

  • According to the Guardian, the newest tests of general relativity started out as “a total fluke,” because the satellites were launched for an entirely different purpose. What were Galileo 5 and Galileo 6 supposed to do?

 

The grid here is spacetime, and it’s being warped by the gravitational field of Earth. Illustration courtesy NASA

The grid here is spacetime, and it’s being warped by the gravitational field of Earth.
Illustration courtesy NASA

  • The Galileo satellites will be testing general relativity, a theory that was published 100 years ago by rock-star physicist Albert Einstein. What is general relativity? Read this anniversary article from NASA for some help.
    • General relativity is nothing less than the “current description of gravitation in modern physics”—that is, everything you ever wanted to know about gravity but didn’t know to ask. Key takeaways:

 

 

What spacetime is it? Galileo’s passive hydrogen maser atomic clocks (like this one) are so accurate they will lose only one second every three million years. Illustration courtesy European Space Agency

What spacetime is it? Galileo’s passive hydrogen maser atomic clocks (like this one) are so accurate they will lose only one second every three million years.
Illustration courtesy European Space Agency

 

These are Einstein’s field equations for general relativity. Good luck! Image courtesy Wikimedia, great featured article on general relativity here.

These are Einstein’s field equations for general relativity. Good luck!
Image courtesy Wikimedia, great featured article on general relativity here.

  • Is E=MC² part of general relativity or gravitational time dilation?
    • No. Einstein’s field equations, a set of 10 equations which mathematically describe gravitation as a result of spacetime being curved by matter and energy, are the most famous equations used to explain general relativity.
    • E=MC², the mass-energy equivalence, is the most famous equation used to explain the special theory of relativity. Einstein formulated the special theory years before the general theory, and first introduced the idea of spacetime there. (Let Einstein tell you about E=MC² here.) The special theory is special because it only applies where gravity has little impact on the curvature of spacetime. According to the good folks at the Max Planck Institute for Gravitational Physics, “the prime example of a situation governed by special relativity is a region far, far away in the depths of space, far away from all stars and planets (and their gravitational influence).”

 

  • Curious about the general theory of relativity? You could do worse than listen to these lectures.

 

TEACHERS’ TOOLKIT

Guardian: Satellite launch accident provides unexpected test of Einstein’s theory

ESA: Galileo Satellites Set for Year-Long Einstein Experiment

Nat Geo: General Relativity Quick Quiz

Nat Geo: Happy Birthday, Albert Einstein

NASA: 100 Years of General Relativity

Einstein Online: General Relativity

Science Questions with Surprising Answers: Does time go faster at the top of a building compared to the bottom? (spoiler alert: yes)

StarTalk: Neil deGrasse Tyson Explains How Gravity Affects Time

(extra credit!) Stanford University: Einstein’s General Theory of Relativity video lecture series

One response to “100 Years Later, Einstein’s Theory Tested by Satellites

  1. Pingback: This Week in Geographic History, March 13 – 19 | Nat Geo Education Blog·

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