NASA/JPL
Detecting that same thing in space.
On Tuesday, at a press conference at the European Space Astronomy Center, scientists announced that they're one step closer to building a giant detector in space called the Laser Interferometer Space Antenna (LISA) that will be able to detect ripples in the fabric of spacetime called gravitational waves.
You've probably heard of the Earth-based Laser Interferometer Gravitational-Wave Observatory (LIGO), which changed history when it first detected these gravitational waves in September. While LIGO can spot what's produced by stars exploding and black holes colliding, LISA will be able to detect gravitational waves that are made when entire galaxies collide. And this would help us better understand how galaxies form and evolve.
Studying the universe in gravity could allow us to see as far back in time as the big bang, NASA scientist Charles Dunn told Business Insider. "It's like opening a new window," Oliver Jennrich, ESA deputy project scientist, told Business Insider. "All of a sudden we learn about things we had no clue existed."
The mission is a collaboration between many institutions, including the European Space Agency (ESA) and NASA.
A soundtrack to the universe
Gravity is currently the least understood force in physics. But thanks to that monumental September discovery we know that extreme events in the universe can create gravitational waves.
When you toss a pebble into a pond, it creates ripples on the surface that spread out, getting fainter as they get further from where the pebble smacked into the water. Gravitational waves do something similar to the fabric of space and time.
It's these waves, or ripples, that scientists are now trying to spot in space. Doing so would let us listen, in a sense, to that 99.6% of the universe that we can never see.
It's more or less like you're walking in a jungle and you can't hear the sound.
"Without sound you wouldn't detect all the life in the jungle," Stefano Vitale, LTP Principal Investigator, told Business Insider. "When you turn on the sound you can recognize the sources - objects you can't see because they're hidden in the jungle. Looking at a gravitational wave is ... like adding the soundtrack to the universe because you see things you cannot see with light."
Free Fallin'
LIGO has made huge strides in helping to detect smaller events of objects close to the mass of our sun. But what about the really big stuff, like the collision of supermassive black holes millions of times the mass of our sun at the center of galaxies?
This is where LISA comes in. To detect things like these, whatever detection system scientists are using must be free from seismic noise from things like Earth moving around, trucks driving, and people walking by.
In that vein, LISA will use a series of tiny 4.6-centimeter gold-platinum cubes, launched into space to get them into a state of near perfect free fall and influenced by nothing other than the sheer force of gravity.
So far, their results have been far better than expected.
"In some peoples minds, what we were trying to do was impossible," Paul McNamara, ESA's LISA Pathfinder project scientist, told Business Insider. "But straight out of the box, on day one, it worked. Not only have we achieved it, we achieved way beyond what asked for."
LISA will be comprised of a triangle of three spacecrafts millions of miles apart. Each of them will house two of the tiny gold-platinum cubes, whose distance will be measured by how long it takes for a laser beam to get from one spacecraft to another.
As a gravitational wave passes through, the geometry of the triangle will change - one arm will get shorter and another will get longer - by about the size of the nucleus of an atom. And this miniscule change is what the scientists will be measuring.
"These events emit more gravitational waves than all the stars and galaxies and everything in the universe combined," McNamara said. "When these two big objects smash together it shakes the entire universe. And we'll be able to measure that."