The Doppler Effect

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Have you ever heard the ice cream truck?

When I was little, I remember hearing the ice cream truck all the time. Just the sound of the opening notes of “Pop Goes the Weasel” were enough to propel me to the door, where I’d beg my parents to let me go out.

Of course, I didn’t always make it out front in time. But one day, my dad found a way to solve that problem—by actually getting in the car and chasing the ice cream truck.

I remember us driving around the neighborhood, following that white truck around. A few times, it slowed and stopped, but when we stopped too, it kept going again. It took a while for the driver to realize we were following him!

Eventually, we caught it, and had a good laugh over it. But the moral of the story is…have you ever noticed that you can tell if something is moving toward you or away from you, just by if it’s getting louder or quieter?

The same trick works for stars…sort of. Continue reading

Einstein: General Relativity


Albert Einstein may have been the genius among physicists, but like all others before his time, he stood on the shoulders of giants.

Einstein did not propose that the sun was the center of the solar system; that idea was already widely accepted when he came around. He didn’t discover elliptical orbits; that distinction belongs with Johannes Kepler.

But Kepler never could figure out why planets orbit the sun in ellipses instead of circles. Even Isaac Newton, who at last identified gravity as the reason we stick to Earth’s surface, couldn’t explain what gravity was—only how it worked.

Einstein provided that explanation with his general theory of relativity. Continue reading

Einstein: Special Relativity


Albert Einstein’s name literally sends shivers down my spine.

This is the man who discovered physics as we know it. This is the man who filled in the gaps where even Newton’s laws of motion went wrong and expanded our understanding of the universe.

This man was a genius in every right—even if his social skills were somewhat lacking.

By the way…I can’t help but notice this is my first post with actual photographs of the scientist in question, instead of portraits. We’re moving along, people…

So. To the point. Einstein is famous for taking revolutionary and widely accepted laws of physics—those that Newton figured out—and showing where there were some holes in the math. But Einstein wasn’t just an annoying critic.

He took it all a step further…and showed us how physics really works.

He came up with the idea of relativity. Continue reading

Newton’s Laws of Motion


It’s said that Sir Isaac Newton was sitting under an apple tree when an apple fell on his head, and that’s when all his discoveries began.

Personally, I doubt that story—just as I doubt that Galileo Galilei ever dropped iron and wooden balls off the Leaning Tower of Pisa. His goal would have been to show that both objects hit the ground at the same time. Unfortunately, wind resistance would have gotten in the way.

Regardless of how Newton discovered gravity, his scientific achievements are monumental. In fact, we recognize him today as one of the greatest scientists to ever live, second only to the famous Albert Einstein.

Newton’s revelation that gravity draws objects toward Earth changed the course of modern science. But what exactly did he find out? Continue reading

Galileo and Motion

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Before Galileo’s time, Aristotle was the god of gravity.

Seriously. Before Galileo came along, the question of how gravity worked was answered with another question: “What would Aristotle say?” Obviously, this method was faulty, since Aristotle was actually wrong about most scientific things he wrote about.

But Galileo began a tradition that would persist into the modern day. He’s credited for having performed the first true science experiments when he observed falling objects.

You could, of course, call Tycho Brahe’s night sky observations and Kepler’s correct application of mathematics to the heavens true science, but neither of them really performed experimental science. That distinction lies with Galileo.

Wait a second…so I thought Isaac Newton was the guy who discovered gravity? Continue reading