How gravitational waves open a new chapter in science

THIS year’s Nobel Prize in physics goes to three physicists who made immense contributions to the detection of gravitational waves. The announcement of this prize comes just a month after scientists announce the fourth time gravitational waves were detected, this time by three detectors instead of just the two used to obtain the first detection.

These back-to-back announcements have the scientific world excited. Why? Because as a milestone, the detection of gravitational waves is on the same level as understanding the role of DNA to life on Earth, or the realization that atoms combined in specific ways make everything up. Better yet, it is at par with the moment Galileo first used the telescope to study the heavens. With the detection of gravitational waves, a new chapter in science begins.

In 1915, Einstein published a theory that improved upon his previous work. This product of a decade of work is one of the greatest products of any human mind, the general theory of relativity. This theory incorporated gravity into Einstein’s original theory on space and time.

Einstein’s theories have many interesting consequences. First, it showed that space and time are inseparable part of the fabric of the universe called space-time. Second, it showed that gravity is a consequence of the way massive objects warp or create “dips” in space-time. Third, it predicted that dips in space-time can ripple outward similar to the way dipping something on the surface of a pond creates ripples that radiate out. This last consequence predicted the existence of gravitational waves.

For years, scientists have labored to detect these ripples in space-time. The first hints that they really exist came from observations of the dance between two massive stars.

In 1974, Joseph Taylor and Russell Hulse measured the tempo of the tango between two special kinds of stars, one a neutron star and another a pulsar (which is an even more special kind of neutron star).

Taylor and Hulse found that the stars are spiraling into each other, which means they are losing gravitational energy. Since energy is neither lost nor created, this indicated that the neutron star and pulsar are making ripples in space-time time like kids making ripples in a pond as they run around each other.

The work of Taylor and Hulse showed that gravitational waves existed, and it won them the 1993 Nobel Prize in physics.

Scientists, however, were not contented in the indirect detection of gravitational waves. They wanted to measure these space-time ripples directly.

There are two big reasons to go after direct detection.

First, directly detecting gravitational waves will allow scientists to study the details of the way space-time oscillates in gravitational waves. This can give clues on whether Einstein’s theory needs revision, and if it does, what kinds of revisions it needs. 

Second, the direct detection of gravitational waves will open up a new window into the universe.

Ever since the dawn of astronomy, observers have been content learning about the universe by studying the light coming from stars, nebulae, distant galaxies, quasars, and other distant objects.

This window into the universe widened when we realized that visible light is just one of many different kinds of electromagnetic waves. There are also microwaves such as the afterglow of the universe’s violent birth. There are radio waves broadcasted by neutron stars. There are gamma rays produced by exploding supernova.

By studying the different kinds of electromagnetic waves that reach us, scientists pieced together the birth of the universe, some of the steps in the formation of new planets, the formation of the atoms that make us up, and so much more.

However, merely looking does not give you the complete experience of a movie. To get that you must also listen. The detection of gravitational waves does something like giving us an entirely new sense through which to understand the universe. By using gravitational waves, it is as if we are now “listening” to the universe in addition to watching it.

It turns out the universe is filled with the violent reverberations of dark, massive monsters; the first gravitational waves we detected came from the violent collision between black holes. It is hard to “see” such collisions because black holes do not produce light. However, their motion creates ripples in space-time that we can now detect.

In the future, scientists are hoping to detect even more space-time ripples coming from the violent explosion of dying stars, the collision between neutron stars, and many other phenomena currently unknown and unimaginable to scientists.

The ultimate prize is to detect the ripples from the very birth of our universe. By trying to detect such space-time wrinkles that are the remnants of our universe’s birth, we learn more about how we all got here.

Pecier Decierdo is the resident physicist and astronomer of The Mind Museum.

Topics: Sound of Science , Pecier Decierdo , gravitational waves
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