For light, time doesn’t exist.

Wikipedia-SunBehindCloud

From the perspective of a ray of sunlight hitting your eye, it reaches you at the same instant it was born on the sun.

We see it taking 8 minutes to reach us, but relativity means that from the photon’s “point of view,” zero seconds have passed.

Einstein figured out that time isn’t the same for everybody.  As something (like a spacecraft) speeds up, time slows down for it.  At the actual speed of light, time doesn’t pass at all.

So if you actually reached the speed of light, you would experience no time at all until you reached your destination.

(Small problem: It’s not possible for anything that has any weight at all to reach light speed.  Light can travel at that speed because it has no mass.)

Still, it means that (at least in a sense) light is always teleporting, reaching its destination in the same moment it departed. All the light you’ve ever seen has done this.

Space movies often have people traveling faster than light.  They gloss over the fact that being able to do that would also necessarily mean being able to move backward in time.

Why a goldfish appreciates art more than you do

The link: The Perfect Yellow, and more

The Story:

There are colors we can’t see.  All around us, every day we’re missing out on something that certain other members of the animal kingdom take for granted.

Just like dogs can hear sounds outside our range of hearing, animals like birds and the boring old goldfish can see colors beyond what’s visible to us.

In terms of the full spectrum of light, we’re practically blind.  The light that’s visible to us is a tiny part of what’s out there.

Electromagnetic radiation

From ultraviolet to visible light to radio waves, they’re all different kinds of the same thing.

Some of the birds you see outside might look drab, but actually have brilliant colors in the part of the spectrum beyond what we can see.  They’re seeing something we can’t even imagine.

The NPR show RadioLab has an awesome story on this unseen rainbow.

Key points are:

  • An American scientist, Jay Neitz, has succeeded in giving the ability to see the color red to an animal formerly unable to see it.
  • He’s working on ways to bring color to colorblind people.
  • Neitz also says it might be possible to give people the ability to perceive colors beyond the normal human range.
  • But there may already be such people in the world.  There are some rare women (normal-looking mutants called tetrachromats) who were born with extra color receptors in their eyes, enabling them at least in principle to see extra color.

The Internet has allowed the discovery of such people to happen.  Before, it was much harder for researchers to connect with the small percentage of the population with this genetic variation.  British neuroscientist Gabriele Jordan has been searching for such people for two decades.  If you think you might be one, and ever plan to be in England, you can contact her.

Megan Arquette is a blogger and possible tetrachromat who was featured on a Japanese science show earlier this year.

Another is an Australian artist named Concetta Antico, whose genetics Jay Neitz is studying.

Study of tetrachromacy is still in its infancy.  Someday within our lifetimes, it may be possible for ordinary people to see what’s been right in front of us all along.  The limits of our perceptions represent a clear and definable limit to the human imagination. You can’t imagine what a bird sees any more than a congenitally blind person can imagine the color blue.

But we’re beginning to push those limits.

What’s Einstein doing under your nose?

Public Domain art from NASA

There’s more than 2 dozen of these machines zipping around the Earth like a giant diagram of an atom, moving so fast it bends space and time.  (image source)

The link: Every day, people rely on Einstein’s time-warp equations without even thinking about it.

The story:

I’m Jay Knitig.  (It’s pronounced “Kinetic.”)  I’m a student at Wichita State University.

What I’m doing here is exploring the awesomeness of everyday life.  Our world is full of amazing things we usually don’t think about or even notice.

The wonders of science are right under your nose.  For example: Albert Einstein’s theory of relativity is abstract and hard to understand, but without realizing it you probably use it in everyday life.  It says that time and space aren’t the same for everyone: Time passes slower the faster you go, and things get smaller.

They don’t just seem smaller and slower, they actually are smaller and slower in your frame of reference.  It’s true for you but something else is true for them.  If one person is traveling at nearly light-speed and another isn’t, they could disagree about which of two events happened first, and both be right.  That’s relativity.

If you have a smartphone, it probably has GPS.  Even if you don’t, a lot of the trucks that deliver stuff to the stores you shop at use it.  GPS relies on a “constellation” of satellites that constantly zoom around the Earth at about two and a half miles per second triangulating with other satellites and your device on the ground.  At that speed (still a tiny fraction of light speed), time has actually slowed down a little for the satellites.

The GPS system people use every day employs Einstein’s time-bending equations to make up the difference.  Without Einstein’s equations, GPS couldn’t work.

Everyday life is full of awesome mind-boggling things just like that.  There are crazy, wonderful things all around us.

You have Einstein right under your nose.