Everybody loves Einstein. They know he was eccentric, socially conscious, a deep thinker and charmingly witty. Fewer people know what Einstein actually discovered in his scientific career. They assume it’s beyond them or too full of math for them to be able to follow. Einstein felt discouraged about this, which is why he published the book Relativity: The Special and the General Theory in 1916. It’s written for the lay person and it explains everything without using math. Princeton University Press has come out with a 100th anniversary edition. We highly recommend it.
A key idea in the General Theory of Relativity is that space and time go together to form a kind of fabric. Objects within space-time shape the fabric according to their mass. This also means that if a massive object explodes, or two massive objects collide, they should send out waves in the fabric of space-time, like the waves we see on the surface of a pond when we toss a rock into it.
One of the reasons Einstein is so revered is that his theories make predictions that are confirmed far into the future. It took 100 years for scientists to detect the gravitational waves that Einstein predicted. They managed it in 2015 using the Laser Interferometer Gravitational-Wave Observatory (LIGO for short). The research team from MIT and CalTech won the Nobel Prize for this achievement in 2016.
The National Science Foundation funds LIGO. It’s an expensive project, involving 1,300 scientists around the world, but it’s s been a major success. It has now detected what seem to be 18 mergers of black holes and 4 binary neutron star mergers. Readers will be familiar with black holes, if only from science fiction. They are a region in space-time where the gravity is so strong that nothing, not even light, can escape. They typically form from the gravitational collapse of heavy stars.
Neutron stars are similar in that they also result from the collapse of a star. They form after a super nova, and are the collapsed cores of giant stars. Their radius is in the range of 10 km, but their mass is greater than that of the sun. They consist almost entirely of neutrons, the neutrally charged particles found in the nucleus of atoms. Neutron stars are also unimaginably dense. A teaspoon of the material from a neutron star would weigh 100 million tons.
LIGO is “making waves” (pun intended) again this week. Along with its sister project in Europe called Virgo, the team has detected something even more fascinating. They believe they may have seen a neutron star collide with a black hole and get gobbled up in the process. This is the first time anyone has seen such an event. The event was detected on April 26, and took place 1.2 billion light years from earth. Assuming they’re right, this means that LIGO and Virgo have observed all three types of black hole and neutron star collision in the universe. They’ve pulled this off in their first three years of operation.
Scientists can tell whether a collision involves black holes or neutron stars because neutron stars emit light when they collide and back holes don’t. Once scientists detect gravitation waves from a collision, astronomers will see a new flash of light in their telescopes in the days that follow. Although the signal from this event is weak, both LIGO facilities detected it, as did the Virgo facility in Italy. That made it easier to pinpoint the location.
Contemplating these massive events in the universe can make us feel small and insignificant. There’s no reason for that, because in our own way we are part of them. Our bodies contain the same neutrons that make up a neutron star. The supernova that generated that neutron star sent out particles of the chemical elements that we consist of along with everything around us. We have a massive black hole at the center of our galaxy. Without it, the Milky Way would never have formed, and neither would the sun or the earth. In which case, we wouldn’t be here.
This false sense of alienation comes from the fact that we don’t have stories to tell us our place in the world anymore. Every culture has a cosmology story and a creation story. In our modern era, science has shown us that our stories aren’t true. We can’t leave it there, though.
We need to learn the new cosmology as best we can. Publishers release lots of books like Einstein’s that are aimed at the average reader. Along with learning about the universe, we need to learn to find the meaning in its story and tell it to one another, including our children. We also need to keep up with science as it fills the gaps in our new story.
There is always more to learn if we dare to know.