Warp Drives: Breaking the speed of light

Elon Musk and his company SpaceX have been working hard to take humans beyond the confines of Earth. He dreams of even starting a colony on Mars sometime in the future. But what about beyond the Solar System? What if we were to travel to Proxima Centauri, the nearest star to us?

Proxima is around 4.35 light-years away. Our fastest spacecraft, Parker Solar Probe, can only travel at around 450,000 mph. Parker will take a whopping 6,633 years to get there.

This particular problem of distance is what Warp Drives aim to solve for us. Warp drives began as a fictional device that helped space crafts travel faster than light. It was made popular by the entertainment series “Star Trek”. Now, Warp Drives are also an active area of research in Physics.

Warp drives in Physics
What we want to do is travel faster than light. But Einstein’s general theory of relativity has made it clear that it is impossible for matter to travel faster than light. Light is made of particles called photons and they do not have any mass. Compared to photons, the matter has mass. To travel at light speeds we will need to supply infinite kinetic energy, thus making it impossible.

But then how will we travel to what lies beyond the Solar System? That question was answered by a Mexican theoretical physicist Miguel Alcubierre. He found that it was possible to travel at light speeds without physically traveling at light speed.

He proposed a device (a warp drive) that could compress the space in front of a spacecraft while expanding the space behind. The device will form a bubble around the spacecraft and curve the space-time to take the craft from point A to point B.

In this approach, instead of increasing the speed, we are reducing the distance we have to travel by folding space. This approach came within the limits of Einstein’s relativity and was a big breakthrough for warp drives.

But the problem was that the device needed Negative mass or a ring of Negative Energy Density to work. We are yet to observe Negative Energy in reality. And to create negative energy density, the drive would need huge amounts of mass to create an imbalance between particles and antiparticles. For a space warp bubble of 100 meters long, according to Miguel, we would have needed mass equal to the entire universe.

This particular roadblock was solved when Chris Van Den Broeck showed that by expanding the volume inside the bubble while keeping the surface area constant, we can bring down the amount of mass, about to the mass of the sun.
Current Developments
As of now, two interesting approaches have come around bringing the idea of warp drives a bit more closer to reality.

Two researchers Alexy Bobrick and Gianni Martire have created a way to modify space-time without the use of negative energy. Though their way shows it is possible to travel with a bubble, it cannot travel faster than light speed.

Another scientist Erik Lens has used a different geometric approach to solving General Relativity, to propose a solution without the use of negative energy. His solution allows a spacecraft with a bubble to travel faster than light.

So can we start the journey soon?
Not at all. These are all mathematical models with no experimental proof. But these are still fascinating developments. The new discoveries are a sign that we are making progress even though it is slower than we expected. But now that we do have a more concrete model, things might just speed up. Who knows by the end of the millennia the spacecraft fitted with warp drives might already be on their voyage to the endless open space.

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