Hitting the Books: Why we can't 'beam ourselves up' Star Trek-style – Engadget

Gene Roddenberry was a man ahead of his time, accurately predicting the development of fantastical gadgets like flip phones, tablet computers, Bluetooth and bionic eyes — even tractor beams. But one technology Roddenberry called for in the 1960s has yet to make it off the screen: teleportation. It’s not only that “we just don’t have enough power,” as Scotty would say, we also lack the fundamental knowledge base to make it a reality. For now, at least. In their latest book, Frequently Asked Questions about the Universe, Jorge Cham and Daniel Whiteson delve into this and a host of other quandaries facing humanity — from whether there’s an afterlife, why aliens haven’t made contact with us yet, or if our observable existence is actually a computer simulation. 
Excerpted from Frequently Asked Questions about the Universe by Jorge Cham and Daniel Whiteson. Copyright © 2021 by Jorge Cham and Daniel Whiteson. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
If your dream of teleportation is to be here in one moment, and then be in a totally different place the next moment, then we are sad to tell you right off the bat that this is impossible. Unfortunately, physics has some pretty hard rules about anything happening instantaneously. Anything that happens (an effect) has to have a cause, which in turn requires the transmission of information. Think about it: in order for two things to be causally related to each other (like you disappearing here and you appearing somewhere else), they have to somehow talk to each other. And in this universe, everything, including information, has a speed limit.
Information has to travel through space just like everything else, and the fastest anything can travel in this universe is the speed of light. Really, the speed of light should have been called the “speed of information” or “the universe’s speed limit.” It’s baked into relativity and the very idea of cause and effect, which are at the heart of physics.
Even gravity can’t move faster than light. The Earth doesn’t feel gravity from where the Sun is right now; it feels gravity from where the Sun was eight minutes ago. That’s how long it takes information to travel the ninety-three million miles between here and there. If the Sun disappeared (teleporting off for its own vacation), the Earth would continue in its normal orbit for eight minutes before realizing that the Sun was gone.
So the idea that you can disappear in one place and reappear in another place instantly is pretty much out of the question. Something has to happen in between, and that something can’t move faster than light.
Fortunately, most of us aren’t such sticklers when it comes to the definition of “teleportation.” Most of us will take “almost instantly” or “in the blink of an eye” or even “as fast as the laws of physics will allow” for our teleportation needs. If that’s the case, then there are two options for making a teleportation machine work:
1. Your teleportation machine could transmit you to your destination at the speed of light.
2. Your teleportation machine could somehow shorten the distance between where you are and where you want to go.
Option #2 is what you might call the “portal” type of teleportation. In movies, it would be the kind of teleportation that opens up a doorway, usually through a wormhole or some kind of extradimensional subspace, that you step through to find yourself somewhere else. Wormholes are theoretical tunnels that connect points in space that are far away, and physicists have definitely proposed the existence of multiple dimensions beyond the three we are familiar with.
Sadly, both of these concepts are still very much theoretical. We haven’t actually seen a wormhole, nor do we have any idea how to open one or control where it leads. And extra dimensions aren’t really something you can move into. They only represent extra ways in which your particles might be able to wiggle.
Much more interesting to talk about is Option #1, which, as it turns out, might actually be something we can do in the near future.
If we can’t appear in other places instantly, or take shortcuts through space, can we at least get there as fast as possible? The top speed of the universe, three hundred million meters per second, is plenty fast to cut your commute down to a fraction of a second and make trips to the stars take years instead of decades or millennia. Speed-of-light teleportation would still be awesome.
To do that, you might imagine a machine that somehow takes your body and then pushes it at the speed of light to your destination. Unfortunately, there’s a big problem with this idea, and it’s that you’re too heavy. The truth is that you’re too massive to ever travel at the speed of light. First, it would take an enormous amount of time and energy just to accelerate all the particles in your body (whether assembled or broken up somehow) to speeds that are close to the speed of light. And second, you would never get to the speed of light. It doesn’t matter how much you’ve been dieting or working on your CrossFit; nothing that has any mass can ever travel at the speed of light.
Particles like electrons and quarks, the building blocks of your atoms, have mass. That means that it takes energy to get them moving, a lot of energy to get them moving fast, and infinite energy to reach the speed of light. They can travel at very high speeds, but they can never achieve light speed.
That means that you, and the molecules and particles that make up who you are right now, would never actually be able to teleport. Not instantaneously, and not at the speed of light. Transporting your body somewhere that quickly is never going to happen. It’s just not possible to move all the particles in your body fast enough.
But does that mean teleportation is impossible? Not quite!
There is one way it can still happen, and that’s if we relax what “you” means. What if we didn’t transport you, your molecules or your particles? What if we just transmitted the idea of you?
One possible way to achieve speed-of-light teleportation is to scan you and send you as a beam of photons. Photons don’t have any mass, which means they can go as fast as the universe will allow. In fact, photons can only travel at the speed of light (there’s no such thing as a slow-moving photon).*
Here’s a basic recipe for speed-of-light teleportation:
Step #1: Scan your body and record where all your molecules and particles are.
Step #2: Transmit this information to your destination via a beam of photons.
Step #3: Receive this information and rebuild your body using new particles.
Is this possible? Humans have made incredible progress in both scanning and 3D printing technologies. These days, magnetic resonance imaging (MRI) can scan your body down to a resolution of 0.1 millimeters, which is about the size of a brain cell. And scientists have used 3D printers to print increasingly more complicated clusters of living cells (known as “organoids”) for testing cancer drugs. We’ve even made machines (using scanning tunneling microscopes) that can grab and move individual atoms. So it’s not hard to imagine that one day we might be able to scan and then print whole bodies.
The real limitation, though, might not be technological but philosophical. After all, if someone made a copy of you, would it actually be you?
Remember, there’s nothing particularly special about the particles that make up your body right now. All particles of a given type are the same. Every electron is perfectly identical to every other electron, and the same is true for quarks. Particles don’t come out of the universe factory with personalities or any sort of distinguishing features. The only difference between any two electrons or any two quarks is where each of them is and what other particles they’re hanging out with.*
But how much would a copy of you still be you? Well, it depends on two things. The first is the resolution of the technology that scans and prints you. Can it read and print your cells? Your molecules? Your atoms, or even your individual particles?
The even bigger question is how much your “you-ness” depends on the tiny details. What level of detail does it take for the copy to still be considered you? It turns out that this is an open question, and the answer might depend on how quantum your sense of self is.
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