Most of the cells in your body are constantly replacing themselves over time, naturally. But, if this happened all in one go, would the reassembled “you” still be you or a clone? As Kaku himself muses: “If you … zap [Captain Kirk] across the room, you’ve now seen Captain Kirk die, you’ve seen his atoms fall apart but here is this other Captain Kirk on the other side of the room, who has the same bad jokes, the same character [and memories] as the original … so who is this imposter? It raises the question: are we nothing but information?”
And there’s a catch.
In 1993, a panel of scientists showed that perfect teleportation was technically possible but in order to work the original thing being copied would have to be destroyed. That’s because in order to measure the exact quantum state of any particle, how it is on its smallest scale, scientists have to disrupt it. To see where it is, you need to bounce a particle of light, known as a photon, off it, but doing so changes its momentum in an unpredictable way, losing all previous measurements about how fast it was travelling. “So you’ve disrupted its quantum state just by measuring it,” Buchler says.
Some imagine we may be able to take a less accurate scan of the body and still recreate someone faithfully, with all the mysterious emotions and chemistry that make them who they are. “Our brains might not be as sensitive to these [quantum mechanical processes], they might not factor in,” Buchler says. “No one knows because no one knows how consciousness works yet.”
Still, the amount of data required to read someone even down to just their atoms is difficult to comprehend. Humans are made up of 37.2 trillion cells, more than there are stars in the sky, and there are trillions more atoms within them. In 1995, physicist Lawrence Krauss calculated that if you stacked up the pile of hard drives needed to store the data of just one human being it would reach light years into space and take longer than the entire life of the universe so far (roughly 13 billion years) to upload anywhere. Imagine the dramatic tension then for the Enterprise crew. It would literally be faster to walk.
Krauss didn’t expect computer storage and transfer speeds to be up to the task until at least the 23rd century, and Buchler admits, even with today’s advances in computing, capturing all of a living organism in data may never be possible. “Even if someone offered me a $20 trillion grant to build a teleporter for an amoeba, I wouldn’t know where to start,” he says.
So teleporting is definitely out?
Light travels faster than anything else in the universe because, unlike everything else, it has no mass to slow it down. It’s so fast, the trip seems instantaneous to a photon. Now, as interstellar ambitions ramp up, breaking (or at least approaching) this universal speed limit has become the focus of serious study. The US military’s research arm launched a project alongside NASA in 2011 with the goal of journeying between the stars next century.
So far, to increase speed, scientists have focused on harnessing nuclear fusion, the intense reaction that fuels the stars themselves. Inside a star, atoms of hydrogen are crushed under enormous weight until they fuse and release energy. A nuclear fusion reaction aboard a spaceship could be trapped and directed from the vehicle’s engine by a powerful magnetic field. Scientists imagine hitting pellets of nuclear fuel, mixed with hydrogen-3 scooped from the gas clouds of Jupiter and Saturn, with lasers until they fuse, releasing energy. A cruder form of this approach is nuclear fission, where small-scale nuclear warheads can be dropped behind a ship and detonated, throwing the vehicle forward at tremendous speed.
Physicist Erik Lentz says such technologies have promise but are difficult to test safely. Instead, he’s watching the new line of beam propulsion ships as likely first contenders for interstellar travel. These designs imagine a future starship as, essentially, a modern sailing ship, with vast sails that can catch a beam of energy shot from the Earth – another laser, perhaps – propelling the craft at a significant fraction of the speed of light.
An international philanthropic effort called Breakthrough Starshot plans to push a fleet of tiny, lightweight spaceships on a laser beam over to Proxima Centauri at roughly one-fifth the speed of light. That would cut the physical journey from 6000 years to 20 or 30. Researchers at ANU say they have worked out the most efficient formation of the lasers to propel the ships – but the project will still require about 100 gigawatts of power (that’s 100 times the capacity of the world’s largest battery today).
As well as energy use, all these options have another problem – how do you avoid hitting things on the way? At such speeds, even a tiny speck of space debris could become a missile. And, in the case of beam propulsion, Lentz wonders: “How do you slow down? These missions are really fly-bys, trying to capture as much information as they can as they whiz by Proxima Centauri at very high speeds. But what happens when we want to send people?”
“Take us to warp, Mr Sulu”: Star Trek ships also come with a handy Warp speed function,Credit:Fair Use
How could dark matter and warp drives help?
When you’re trying to cross inhumanly vast distances, perhaps it would just be easier to move space itself. Einstein’s seminal theory of general relativity told us nothing can travel faster than light, but it also ruled that time and space really are part of the same fabric of the universe: spacetime. And energy and mass can distort it. So big hefty objects such as planets, stars and black holes curve spacetime around them – this is what we feel as gravity.
In 1994, the physicist Miguel Alcubierre showed that it was theoretically possible within Einstein’s laws to compress spacetime in front of a ship while expanding it behind, thereby moving space itself around a small area in a “warp drive” or bubble. The problem is that moving space in such a way requires not only a staggering amount of energy but, according to Alcubierre, an entirely different form of it – negative energy or dark energy, the mysterious force that scientists believe is speeding up the expansion of the universe. “No one has found what dark matter is yet,” Lentz says. “Everything we see and feel, you and I, our atoms, all have positive mass, positive energy, when we measure it.”
Einstein also theorised that it might be possible to fold spacetime, creating a tunnel or shortcut between two distant locations, possibly even two different times, known as a wormhole. While these phenomena are already beloved staples of sci-fi, from Stargate to Dr Who, scientists are yet to find one in real life, and if they did it’s thought that negative energy would again be needed to hold it open long enough for a ship to safely travel through.
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Lentz has spent much of his own career hunting for dark matter but in 2020, while in pandemic lockdowns, he decided to consider again: would a warp drive really need this kind of negative energy to work? “That’s when I found another loophole,” he says. By adjusting the geometric design of Alcubierre’s warp bubble (which traditionally is shaped like a wave, cresting up as spacetime expands behind the ship), Lentz calculates you could create the bubble from normal energy alone – he imagines using a super-dense plasma hot enough to generate powerful magnetic fields. “Inside the bubble, you’d still have that flat, safe harbour for the ship to rest, about 100 metres wide,” he says. “But all around it’d be rough seas rather than one nice wave.”
Lentz’s design would still require an “astronomical amount of energy in the literal sense” but if it holds true in theoretical models he says that’s a problem for engineering to whittle down “from the mass of the sun to the gram scale”. “The point would be it’s possible.”
So does a warp drive solve his collision concerns? Strangely, Lentz says, it actually throws up another altogether. As the warp bubble moves spacetime, cosmic debris would accumulate along its front, like bugs on a windshield. By the time you pull up at Proxima Centauri, Lentz says, all that built-up radiation would be cast off the front of the bubble in a potentially world-destroying beam of energy. “We think it’d be high intensity, short duration, so we’d need to design a better windshield that doesn’t let things build up. Again geometry could help us.”
Even more concerning, he says, is the event horizon that would form around a ship travelling faster than light, as time itself seemed to fall away. “Around you, the universe would disappear, you wouldn’t be able to see out or communicate, even with the plasma [forging the warp bubble], so how would you slow down?”
He imagines you could set up stations all the way along the proposed route, with devices ready to slow down or control the bubble from the outside. But that would make relying on warp to take us out of the solar system a bit like driving along a highway that hasn’t been built yet. We’d have to put in the hard yards first.
So does that mean we’ll be living in space? Or other planets?
Suppose we don’t have the engineering breakthroughs needed for high-speed travel (or to make humans zoom through the years frozen, ageless, in cryogenic storage). In that case, sci-fi authors imagine sprawling, self-sustaining ships, big enough to support a population of humans for the centuries needed to make an interstellar voyage. Scientists are thinking along the same lines, and have already done a lot of modelling on how they would work.
They might be steered by artificial intelligence and numbers onboard would likely run to the thousands, enough so that if disaster wiped out a chunk there would still be enough people to fill all the skilled roles needed. Such ships could become like cities, even planets, of their own, with inhabitants tending crops under UV lights, and entire civilisations rising and falling; long after Earth has disappeared from view.
Something in this picture, of traversing the vast oceans of space in search of new worlds, seems intrinsically human to ANU astrophysicist Brad Tucker, whether you grew up watching Star Trek or not. In Interstellar, filmmaker Christopher Nolan imagines humans searching the galaxy for a another home after disease and the climate crisis make the Earth unliveable. But, as Tucker notes, even an earth in climatic upheaval beats most options nearby. “There is almost nothing we could do to the earth that would make it as inhospitable as Mars,” agrees Swinburne astrophysicist Alan Duffy.
Still, Elon Musk, the billionaire entrepreneur behind SpaceX, argues that as humanity is totally reliant on Earth, it also needs a back-up plan. And he sees Mars as the obvious answer. Venus and Mercury appear uninhabitable; and Jupiter and Saturn’s moons are too far away to colonise.
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“[Mars] is still quite extreme, but compared to the moon it’s … more like Earth,” says Professor Akbar Rhamdhani, who is working on ways of extracting metals from Mars’ red soil at Swinburne University. “On Mars, we have [some] atmosphere, unlike the moon. It contains CO2 [which can be converted into oxygen or plant fertiliser]. On Earth, we make metals using carbon – and there is carbon on Mars.”
There is also ice, which means not just water but the means to produce a methane rocket fuel when combined with carbon dioxide.
To get enough people to go, Musk envisages the cost of one-way transit would need to fall to around $US200,000.
But Duffy says radiation will be the biggest hurdle. Beyond Earth’s protective atmosphere and magnetic field, space is filled with cosmic radiation: high-energy particles spewed from our sun, exploding stars and black holes. NASA estimates a one-year round trip would expose an astronaut to about 600mSv (millisievert) of radiation, minimum, while staying on the surface increases the dose. A single chest X-ray is 0.3mSv. To keep your Mars colonisers from dying of cancer, you’d need some form of shield.
And how would we go actually living there? As Duffy notes, the psychological state of our pioneers is likely to come under strain so long in the extremes of space. But two experiments on opposite sides of the world offer clues.
In Arizona in the 1980s, a wealthy Texan – influenced by a group of hippies who believed they were watching the downfall of Western civilisation – built a huge closed habitat complete with rain forest, mangroves, and coral reef, plus about 3800 species of plant and animal. Biosphere 2 was supposed to prove we could build a circular habitat, where everything needed for human life was constantly recycled. Instead, it proved just how challenging and fragile life on another planet would be. In the experiment, microbes in Biosphere 2’s soil grew too large, taking too much oxygen from the air and leaving the people inside with altitude sickness. Crops failed to grow. Hummingbirds and bees died while cockroaches and mites thrived, attacking plants.
However, incubating in the frozen wastes of Siberia was an experiment that has enjoyed much less publicity – but was much more hopeful for humanity’s chances of settling other planets (and giving our pioneers an easier time of it than Matt Damon in The Martian).
BIOS-3 is a sprawling underground bunker in Siberia created in 1965 by Sergei Korolyov, the father of Soviet space exploration. Designed specifically to test closed environments for life on the moon or Mars, it housed volunteers in one wing while in the others grains and vegetables grew under UV-lights. The plants cleaned the air and recycled the water to boot. Water vapour from an astronaut’s breath could be condensed and recycled while their solid waste could be used to fertilise plants. Volunteers stayed happy and healthy, and the system perfectly stable during the six-month test. “Not only did the crew remain healthy but the quality of air, water and vegetables did not deteriorate during the period of closure,“ wrote the Soviet scientists behind the project. In the event it was ever set up on another planet, meat could be supplied from Earth via resupply missions, they noted; the Soviets never considered going vegetarian, as “Siberians must have their meat”.
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Designs for living on the red planet continue to advance. Australian firm Hassell, for instance, was shortlisted for a NASA-run competition in 2018 to design a liveable Mars habitat: they went for a shell-like structure built of layers of Martian soil, which could be heated up and turned into a substance similar to concrete. The hard shell would protect the crew from meteorites and other Martian dangers (yes, meteorite hits are common on the crater-pocked planet, with its atmosphere just 1 per cent the thickness of Earth’s). Inside the shells, modular inflatable pods would provide space for astronauts and experiments.
Of course, by the time we are thinking seriously about making the red planet our second home, Maku says others revolutions, in synthetic biology and genetic engineering, on Earth may allow us to terraform or transform the planet, beyond just enclosed habitats, to better suit our needs.
And life on Mars will change us too, he says. For one, the gravity is less than a third that of Earth. Just imagine what ballet dancers and figure skaters, our top athletes, even Star Trek’s champion fencer Mr Sulu, could do with that.
Also in this sci-fi explainer series …
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