The Theory of Relativity in less than 10 minutes

Gabrielle Birchak/ May 16, 2025/ Modern History/ 0 comments

PODCAST TRANSCRIPTS

It’s Flash­cards Fri­day at Math! Sci­ence! His­to­ry! and since we’re doing a short pod­cast, I couldn’t think of a bet­ter top­ic to do than a Flash­card about Albert Einstein’s The­o­ry of Relativity.

I’m Gabrielle Bir­chak. I have a back­ground in math, sci­ence, and jour­nal­ism. By the time you’re done lis­ten­ing to this brief pod­cast, you will know more about this ground­break­ing the­o­ry that changed how we think about space, time, and the uni­verse. And don’t wor­ry, by the end of this episode, you won’t need a physics degree to under­stand it. We are tak­ing the scenic route in a fic­tion­al elec­tric vehi­cle I like to call the Ein­stein-EV.

So, buck­le up, plug in, and let’s take a dri­ve through space and time.

Before we hit the road, let’s set the scene.

It’s the ear­ly 1900s. Albert Ein­stein is a young patent clerk in Switzer­land, not yet the wild-haired glob­al icon of genius we all know. But even then, he’s already full of deep ques­tions that keep him up at night.

Ein­stein is obsessed with one thing: light. He’s not the only one. The late 1800s and ear­ly 1900s were a gold­en age of sci­en­tif­ic dis­cov­ery. James Clerk Maxwell had shown that light was an elec­tro­mag­net­ic wave that could trav­el through space with­out a medi­um. That baf­fled a lot of people.

Back then, sci­en­tists thought that waves need­ed a medi­um to trav­el through, like sound needs air or water needs, well, water. So, what did light trav­el through?

They called it the luminif­er­ous ether, a kind of invis­i­ble, weight­less sub­stance fill­ing all of space. But no one could find it.

Ein­stein wasn’t sat­is­fied with these expla­na­tions. And that brings us to our first stop in the Einstein-EV.

IMAGINING THE IMPOSSIBLE, THE TRAIN OF THOUGHT

Ein­stein once said that his great­est skill was not being smarter than oth­ers. It was being will­ing to think dif­fer­ent­ly. I don’t know judg­ing by my last pod­cast, maybe his great­est skill was manip­u­lat­ing women to get what he want­ed. Be sure to check that one out. It’s all about his first wife, Mil­e­va Mar­ic. But no doubt, he was a bril­liant man.

One of his ear­li­est thought exper­i­ments involved a train. Imag­ine you’re stand­ing at a train sta­tion, and a train is speed­ing by. On that train, a per­son stands exact­ly in the mid­dle of a car. At the exact moment, two bolts of light­ning strike the front and back of the train.

To the per­son on the train, the light­ning strikes appear to hap­pen simul­ta­ne­ous­ly. But to you, stand­ing on the plat­form, it looks like the light­ning hits the front of the train before the back. Why? Because the train is mov­ing forward.

If some­thing as basic as whether two things hap­pen simul­ta­ne­ous­ly depends on how you’re mov­ing, what does that say about time itself?

Let’s switch gears and hop into our imag­i­nary elec­tric vehi­cle, the Ein­stein-EV. It’s sleek, silent, and just like real elec­tric vehi­cles, it moves pret­ty fast. But ours is spe­cial. It comes equipped with a light-speed dashboard.

Now imag­ine two peo­ple in two sep­a­rate Ein­stein-EVs. One is parked, and the oth­er is zoom­ing down the high­way at near­ly the speed of light. Both dri­vers turn on their head­lights at the exact same moment.

Here’s where it gets wild: even though one vehi­cle is mov­ing, both dri­vers mea­sure the speed of light com­ing from their head­lights as pre­cise­ly the same, 186,000 miles per sec­ond. That’s the cos­mic speed limit.

But wait. If you’re mov­ing toward the light source, shouldn’t it look like the light is approach­ing you faster?

This para­dox is at the heart of spe­cial rel­a­tiv­i­ty, Einstein’s 1905 the­o­ry that rewrote the rules of physics.

THE CORE OF SPECIAL RELATIVITY

Spe­cial rel­a­tiv­i­ty is built on two sim­ple ideas:

1. The laws of physics are the same for every­one, no mat­ter how fast they’re mov­ing, so long as they’re not accelerating.
2. The speed of light is con­stant for all observers, no mat­ter how fast they move.

To make these two ideas fit togeth­er, space and time can’t be rigid. They must be flexible.

If the speed of light doesn’t change, then time must.

Yes, you heard that right: time slows down the faster you go.

This is called time dila­tion. If you were to dri­ve the Ein­stein-EV near the speed of light and then return to Earth, you’d have aged less than the peo­ple who stayed behind.

This isn’t just sci­ence fic­tion. We’ve test­ed it. GPS satel­lites orbit­ing Earth tick at slight­ly dif­fer­ent rates than clocks on the ground because of relativity.

And it’s not just time that’s stretchy. Dis­tances con­tract when you’re mov­ing fast, an effect called length con­trac­tion. To you, the road gets short­er as you speed up.

This might sound like a glitch in the Matrix, but it’s very real.

BUT WHAT ABOUT GRAVITY?

Okay, so we’ve got spe­cial rel­a­tiv­i­ty down. But that only works when objects move in straight lines at con­stant speeds, with no speed­ing up, no slow­ing down, and no gravity.

But grav­i­ty exists. It pulls apples to the ground, keeps the Moon in orbit, and holds galax­ies togeth­er. So what gives?

This both­ered Ein­stein. And for the next ten years, he worked on a new the­o­ry, a big­ger one, called gen­er­al rel­a­tiv­i­ty.

And here’s where he had anoth­er flash of insight.

FALLING FREELY, THE ELEVATOR EXPERIMENT

Pic­ture your­self inside a win­dow­less ele­va­tor float­ing in deep space. Sud­den­ly, you feel your­self pressed to the floor.

How do you know whether the ele­va­tor is sit­ting on Earth or being pulled upward through space?

Ein­stein real­ized you can’t tell the difference.

This led to what he called the equiv­a­lence prin­ci­ple, that being in a grav­i­ta­tion­al field is indis­tin­guish­able from being in an accel­er­at­ing frame of reference.

This was a game-changer.

Ein­stein now imag­ined that grav­i­ty wasn’t a force like New­ton thought. Instead, he pro­posed that mas­sive objects, like stars and plan­ets, bend space and time around them like a bowl­ing ball bends a trampoline.

And if you put a small­er ball on the tram­po­line, it rolls toward the big­ger ball, not because it’s being “pulled,” but because it’s fol­low­ing the curve.

In oth­er words, grav­i­ty is geom­e­try.

BACK IN THE EINSTEIN-EV, TURNING THE CURVE

Let’s get back into our Ein­stein-EV for a moment.

You’re dri­ving on what looks like a straight road. But unbe­knownst to you, the road is on a giant curved sur­face, like a planet.

Even if you’re not steer­ing, your car will slow­ly start to veer. Not because you turned the wheel but because the path itself is bent.

That’s what grav­i­ty does to space. And that’s what gen­er­al rel­a­tiv­i­ty explains.

PROOF IN THE STARS

So, how did we know Ein­stein was right?

In 1919, British astronomer Arthur Edding­ton observed a total solar eclipse. Dur­ing the eclipse, he looked at how stars appeared near the Sun. Accord­ing to New­ton, their light should pass by the Sun in a straight line.

How­ev­er, accord­ing to Ein­stein, the Sun’s mass would bend space­time and curve the light, just like our tram­po­line analogy.

Eddington’s team found that the stars’ posi­tions had shift­ed, just as Ein­stein predicted.

The result? Ein­stein became a glob­al super­star. For the first time, a sci­en­tif­ic the­o­ry had shown that space itself could be warped.

WHY THIS STILL MATTERS TODAY

So you might be won­der­ing, okay, cool sto­ry, but what does this mean for me?

It means a lot.

• GPS wouldn’t work with­out rel­a­tiv­i­ty. Satel­lites expe­ri­ence time dila­tion (spe­cial rel­a­tiv­i­ty) and grav­i­ty-based time warp­ing (gen­er­al rel­a­tiv­i­ty). Your loca­tion would be off by miles if we didn’t adjust for that.
• Black holes? Pre­dict­ed by gen­er­al relativity.
• Grav­i­ta­tion­al waves? First observed in 2015, rip­ples in space­time were caused by col­lid­ing black holes, exact­ly as Ein­stein had predicted.
• Time trav­el the­o­ries? Based on relativity.

And yes, even your cell phone’s clock owes a lit­tle nod to Einstein.

EINSTEIN’S THOUGHT PROCESS, HOW HE GOT THERE

Let’s pull over for a sec­ond and reflect on how Ein­stein even devel­oped these ideas.

1. He asked sim­ple ques­tions, What hap­pens if I ride along­side a beam of light?
2. He trust­ed thought exper­i­ments over labs. His mind was his laboratory.
3. He looked for beau­ty and con­sis­ten­cy. Ein­stein believed the laws of nature should be ele­gant and universal.
4. He chal­lenged author­i­ty. Just because New­ton said space and time were absolute didn’t mean it was true.
5. He embraced imag­i­na­tion. In fact, one of his most famous quotes is: “Imag­i­na­tion is more impor­tant than knowledge.”

So, here we are, back in our dri­ve­way, the Ein­stein-EV pow­ered down.

You might not be dri­ving near the speed of light any­time soon. But every time you use GPS, mar­vel at a solar eclipse, or think about the vast­ness of the cos­mos, you’re touch­ing the edges of a the­o­ry that for­ev­er changed how we see the universe.

Einstein’s the­o­ry of rel­a­tiv­i­ty showed us that space and time are not fixed. They’re dynam­ic, bend­able, and deeply connected.

And per­haps most impor­tant­ly, it reminds us that the uni­verse still has room for curios­i­ty, imag­i­na­tion, and wonder.

Thanks for tak­ing this jour­ney through the the­o­ry of rel­a­tiv­i­ty with me on Math! Sci­ence! His­to­ry! Until next time, carpe diem!