Why should we bother looking for Gravitational Waves?

26/4/2019 mid sem Holiday is almost up. I Better get started on that ASTR 800 (Advanced Topics in Astrophysics) paper.

Break is over, better get started on that term paper.

So I want to talk about Gravitational Waves, more so the importance of finding gravitational waves.

Why do we need to find these elusive ripples of propagating space time called Gravitational Waves?

For a long time Gravitational Waves seemed to be secluded within the realm of theoretical physics. The idea was born out of the mind of Einstein while the experimentalists in the room which included Richard Feynman and Joe Weber could only dream of detecting them. Some of those early  experimentalists although daring in the quest for gravitational waves are no longer with us, were not able to make it to witness the progress we have made today.

But the first Ligo Gravitational Wave observation happened in 2016 and we can now pinpoint their origins to Supermassive Black Hole Binaries (SMBHB) and Neutron Star Binaries (NSB). Wherever there are really dense astronomical objects orbiting each other in an inspriling cosmic death dance. That is where the origin of gravitational waves can be pinpointed to.

In-fact these events are responsible for the formation of heavier elements in the Universe like Gold and Platinum. So you are essentially buying for your spouse a briproduct of the most violent collisions in the Universe.... just like my relationships.

But why do Astronomers have a vested interest in detecting these gravitational waves?

Well that is an interesting question actually. I mean are not observations in the EM domain enough to learn us all we can about the Universe that we live in and the Cosmos from which we spring?

Well, I can tell you that the answer to that is No. Because of something called Multi Messenger Astronomy.

We live in the age of Mutli-Messenger Astronomy (MMA) which is this idea that we can acquire much more information about the universe by looking at signals that reach us in different ways. Here are the 4 ways that information about the Universe can reach us.

• EM - Light. The classic Medium of Discovery. From Planets to Pulsars this is how its been done since back in the day.
• Gravitational Waves - Ripples of Propagating space time. These can tell us about the merging of really dense objects in the Universe. Black Holes and Netutron Stars
• Neutrinos - Elusive Tiny Particles travelling at the speed of light.
• Cosmic Rays - High Energy Particles. Can tell us about  Gamma Ray bursts

Some of things out there may be detectable by the many different media, others in singularly different ones. but there is a wealth of information that can be conveyed by analyzing the same cosmological phenomena in the different messenger media.

One example is how the Gravitational Waves detected by LIGO are quickly followed up by observations by Radio Telescopes. etc.

But what really convinced me about MMA  surrounds some discoveries that happened around the time of my birth (1992). That is the discovery of PSR B 1257 + 12 and the planets that surround it. Draugr, Poltergeist and Phobetor.

I wonder if it will have an atmosphere. Not that we really need one if we ever get to explore it. I figure we'll carry our own atmosphere with us.

These 3 planets orbit the husk of a star that went supernova a long time ago. That star is survived today as a pulsar that periodically emits beams of electromagnetic radiation  The planets were discovered by measuring the variation in Doppler shift of pulsation Period.

This planet marks the discovery of an extrasolar planet via means of Pulsar Timing.  One of the worlds was discovered to be twice the size of the moon at 0.02 Earth Mass, the smallest planet ever to be discovered. In all the planets discovered by the Kepler mission in the modern age. Pulsar Timing in 1992 (the year that I was born) revealed to us a world in a category of its own. A tiny little speck orbiting a Pulsar.

That remarkable discovery was made via an indirect observation by studying subtle changes in the propagation of light. we didn't see the planet optically but implied its existence by looking at the effect it had on the pulsar signal, thus confirming its existence.

Now extend that to Gravitational Waves and the information they carry, and the things we might come to learn of when we detect Grav Waves. What new wonders undreamt of in our own time would will we discover by studying gravitational waves? 

Lets find out...