Will ESA's newly launched probe prove Einstein's last prediction was right?

It was one of the most important implications of Einstein’s theories. And now the European Space Agency is going to see if we can find gravitational waves.

How do you detect gravitational waves? For one, it’s very difficult to prove anything about them in experiments in Earth’s gravitational pull. Even in free-fall in space, you need instruments of unprecedented accuracy to measure any variation in gravitational effects at all.

Wait, there can be waves in gravity?

Yeah! Well, it's more accurate to imagine them as ripples, really. They radiate out from really extreme interstellar phenomena, like spiralling black holes or neutron stars about to merge.

So about that Pathfinder probe...

Remember how you need some really sensitive, laser-powered equipment to detect gravitational waves? This happens to be exactly what ESA launched into space today, with the LISA Pathfinder craft. This probe is set to travel toward the Sun until it reaches the first Lagrangian point between Earth and its star.

Here, thanks to the gravitational pulls of both the Earth and the Sun, LISA Pathfinder is able to achieve a stable orbit around the Sun. This is paramount to the gravitational experiment. 

Two cubes and lasers power the experiment

In order to find evidence of Einstein’s predicted gravitational waves, Pathfinder carries an experimental setup consisting of two cubes, offset from each other by exactly 38 centimetres, with an ultra-accurate laser measurement system in between. This system is accurate up to “a billionth of a millimetre,” and may be able to show variations in the gravitational field in the space between the two cubes.

This is already hugely exciting, and if LISA ends up confirming Einstein’s predictions, then this would be huge for the astrophysics world. What’s even more thrilling however, is that if the experiment is successful, it will open the way for more extensive observatories to be launched into orbit.