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What Einstein Missed: Where Relativity And Road Trips Meet


Yes, it was Albert Einstein who unified space and time together into a single, coherent whole. As a physicist I can say that was a pretty impressive feat, but as parent — slogging across interstate whateveron the last weekend of the summer — I have to ask: What's the big deal?

Anyone stuck in vacation traffic with kids in tow can tell you that Space and Time have always been unified but not in the wiggly, abstract sense my buddy Al Einstein was talking about.

No, if you're like me, you have already experienced the way the two can merge into one giant, sweaty, chewing-gum wad of boredom and rest stops that is the principle of Highway Holiday Relativity. Here's how it works.

As the first scent of autumn rises like a ghost in the morning and the desperate desire for just one more trip to the lake burns away our good sense, it's a good time to review the basic equation of Highway Relativity. It pretty simple and it goes like this...

Time = Space = Your foot. As in, your foot on the gas pedal.

Now you may think you hate physics but I think you know exactly what I'm talking about. Lets review.

Deep into that 380 mile drive from your house to your cousin's place on Lake Arewethereyetyou pass under one of those big green interstate placards. It tells you there are 250 miles to MiddleofnowhereFalls the last big city before you turn north to the lake. You're hungry, hot, tired and need to go to the bathroom. This is when the Highway Relativity calculation begins.

The time you have left in the sweaty car equals the distance you still have to cover divided by the speed at which you are traveling.

Now you could ask someone in the car with a calculator enabled cell phone to divide the 250 miles you still have to cover by your current speed of 65 mph. But after the whole morning in the car everyone has already been bored into a coma. So instead you round everything off and arrive at about 4 hours. Yes, it's true. You still have 4 interminable more hours left behind the wheel.

But the principle Highway Relativity still has so much more to give. How much less time would it take to cover the same space if you just inched your speed up to 70 mph? And why be stingy? How about 75 mph? 78? 80 even?

Einstein's theory of relativity had no ethics attached to it but Highway Relativity is not so agnostic about human affairs. Yes, more space will be covered in less time if your foot simply got heavier on the gas pedal. But your family's safety and that $200 speeding ticket drag at your wheels and your conscience.

And there, right there, is where the ethics of Highway Relativity and physics of Einstein's relativity finally meet: Einstein taught us that time does not flow at the same rate for everyone. Highway relativity teaches us the same. For your cousins at the Lake time is flowing as gently and freely as the breeze running off the water. But for you, time just hangs in the air like the hot sun beating through the windows.

Oh look, there's road construction up ahead...

You can keep up with more of what Adam Frank is thinking on Facebook.

Copyright 2020 NPR. To see more, visit https://www.npr.org.

Adam Frank was a contributor to the NPR blog 13.7: Cosmos & Culture. A professor at the University of Rochester, Frank is a theoretical/computational astrophysicist and currently heads a research group developing supercomputer code to study the formation and death of stars. Frank's research has also explored the evolution of newly born planets and the structure of clouds in the interstellar medium. Recently, he has begun work in the fields of astrobiology and network theory/data science. Frank also holds a joint appointment at the Laboratory for Laser Energetics, a Department of Energy fusion lab.