Posted in Space & All Things Science

Gravitational Waves: What Next?

I’ve recently been writing an assignment on gravitational waves, so I thought I might share some of what I have learned with you!

Gravitational Waves are a big thing in physics. Einstein predicted them in 1916, but nobody was quite sure about their existence till 2016. Einstein – in his Theory of General Relativity – combined space and time and described bodies acting on this space-time plane to attempt to describe Gravity.

I’m going to use a trampoline as an example. If you stand in the middle of the trampoline, it curves under your weight beneath where you stand. This is the same for planets, stars and other astronomical objects, curving space-time. Now imagine you are jumping on the trampoline (not large jumps, but little bounces). If you think about the material of the trampoline as you bounce, you would be right in thinking that your bounces would create little ripples in the trampoline. Similar to when you throw a pebble into water, these waves radiate outwards from you, and depend on how heavy you are and how energetic you are. These ripples are gravitational waves.

To summarise, gravitational waves are created by massive objects and energetic processes in our Universe. They are ripples in space-time and gravitational waves travel at the speed of light.

So, if Einstein predicted them in 1916, why was it such big news in 2016? To put it briefly, nobody believed Einstein. Scientists need evidence to support a theory and despite being a brilliant theory (which turned out to be true in the future), Einstein couldn’t prove his theory was correct.

Many people tried to detect gravitational waves. In 1974, we did find proof that gravitational waves were acting on a binary pulsar system (see http://www.astro.cornell.edu/academics/courses/astro201/psr1913.htm – a brilliant source and an extensive explanation of the Hulse-Taylor pulsar system). It was in 2016 that Physicists directly observed a gravitational wave. LIGO detected a wave of 35 – 250 Hz signal (Read Observation of Gravitational Waves from a Binary Black Hole Merger for more info)  that couldn’t be explained by any activity here on Earth, but did match a prediction of gravitational wave emissions from a binary black hole system. A year later, LIGO and other interferometer observatories have detected many signals of gravitational waves. (Future post explaining Interferometers to come!) The evidence is stacking up, therefore scientists are becoming less sceptical of General Relativity and Gravitational Waves.

So, what next? In the immediate future, we are still using interferometers to find new signals and collect more and more data. However, our observations of gravitational waves from Earth’s surface remains limited. There is so much noise and activity on the surface that weaker signals cannot be detected. We can’t exactly ask the human population to sit still and remain quiet whilst we measure gravitational waves! So, Scientists hope to develop space interferometers to detect those weaker signals (such as emissions from single pulsars). Also, we hope to use a collection of pulsars (known as Pulsar Timing Arrays) to observe gravitational waves acting on objects. We can’t see the effect a gravitational wave has on Earth, so we must look out at others.

You might be wondering why gravitational waves are so exciting for Physicists. Well, it might come as a shock to say that we don’t really understand Gravity. It’s a force that governs everything we know and, many people would think, the easiest to understand . You only have to jump up and down to experience Gravity. However, Scientists wouldn’t agree. In this picture of the Universe they are trying to build, Gravity doesn’t fit in. So Scientists hope that by investigating General Relativity and Gravitational Waves, we’ll get closer to understanding and explaining Gravity.

Advertisements
Posted in Random Ideas!, Space & All Things Science

Inspiring Humans – Piers Sellers

We all have people we look up to, follow by example and live in awe of. I’d like to share a few famous faces (and some less so) who I am inspired by. I’d love to know who you’re inspired by – leave them in the comments below!

I’ll be honest – I only found out about Piers Seller after watching Leonardo Di Caprio’s documentary, Before The Flood, in a Geography lesson about Climate Change a couple of months ago. The documentary itself was good, apart from the carbon footprint Di Caprio clocked up shooting a documentary about reducing your carbon footprint to save the Earth!

Anyway, Piers was interviewed by Di Caprio about NASA’s stance on Global Warming. Watch the interview with Leonardo. Watch any of his talks. Because what Piers says is more powerful than anything I could write.

That particular interview rings emotional bells for me because a) I’m an environmentalist at heart and b) because I’m human. And any human can see the selflessness and beautiful kindness that is demonstrated by a dying man whose only wish is to save our dying planet. Despite the fact that he will never see the changed planet he’s fought so hard to save.

Piers died on 23rd December 2016 from Pancreatic Cancer. I think we all have a lot to learn from the veteran astronaut of three missions and six spacewalks who spent his final days fighting to save the world that we take for granted.

Posted in Space & All Things Science

A Little Green Man

Astronomy has existed for as long as humans have existed; from Chinese Astronomers in 1054 observing a supernova brighter than the Sun (the now Crab Nebula exploding) to sailors charting the heaven’s constellations and using the stars to navigate (not forgetting the greats – Galileo, Copernicus, Newton). However, much of astronomy has developed thanks to the advancement of electromagnetic telescopes. Jodrell Bank – A radio telescope in Cheshire!

These telescopes have vastly shaped the universe we see for the last 50 years. Picture this: It’s 1967 and Jocelyn Bell Burnell is conducting research on high energy galaxies (or quasars). She picks up a regular repeating signal – a pulse – in the distant universe. With no real explanation, she names it LGM1, Little Green Man 1.

Funnily enough, she believed an alien civilisation were disrupting her PhD. (you can imagine how annoying it would be for an alien civilisation to interrupt you whilst you were doing homework… he he!) Unbeknown to her, Bell had just discovered a star, the size of a city, rotating up to 700 times a second. She had discovered…

…a pulsar!

It’s quite a nice theory to understand: the mechanisms behind a pulsar. After a star more massive than our Sun (between 10 and 30 times bigger) has fused everything it can*, it explodes in a supernova and leaves behind an extremely dense condensed ball of matter. Previously, protons, neutrons and electrons all existed within the star, happily in their own personal space (due to forces of repulsion and attraction). When forced into close proximity, the empty space that makes up 99.9999…% of an atom is squeezed out and electrons are forced into the nucleus. They then combine with protons to produce neutrons (sort of like beta decay, but in reverse!)

This is how a neutron star is formed. It’s just a sphere of pure compacted neutrons, but it’s 40 billion times denser than lead!

But what makes a neutron star a pulsar? First, the neutron star must have a companion. Before the supernova, pulsars exist as part of a binary star system (two stars ‘stuck’ together due to gravity holding them in orbit around each other). However, pulsars are very rare because it’s one thing having a companion, but another thing entirely keeping them (quite relatable to real life, wouldn’t you agree?). The supernova is so powerful an explosion that the force of gravity between the two stars must be strong enough so the companion doesn’t blow away.

The companion is essential because they provide fuel for the pulsar. Yes, you could say the pulsar eats its friend (Please can I note, DO NOT EAT YOUR FRIEND – it’s not a good move and they might not want to be your friend anymore 🙂 In a physicsy sense, the neutron star has such an intense magnetic field that it rips electrons from the companion’s surface.

*Here’s the tricky bit!*

The electrons travel away from the companion’s poles and towards the pulsar’s poles. As it moves away, the electron is accelerated to very high speeds; so fast, that the electrons emit an electromagnetic wave (often X-Rays). All that is left to add is that as the pulsar rotates, the poles where E.M waves are emitted move relative to us (Earth). Therefore,

the region of E.M wave emission pulses because it travels across our line of vision.

Let me just repeat this again (it’s crucial). We see a pulse as the area of E.M waves crosses our line of vision here on Earth.

And that’s it! When you understand the science of pulsars, you can see why Bell thought she’d stumbled across a beacon from alien civilisations. A pulsar acts just like a lighthouse!

*Coming Soon – Why Does the Sun Shine?

Posted in Space & All Things Science

My Top 10 Sun Facts

After recently visiting Kielder Observatory whilst on holiday, I’ve renewed my interest for our nearest star, The Sun. So here’s a quick ‘Top Ten’ facts I know about the Sun:

1)The Sun is 1,400,000 kilometers wide. That is 100 times larger than the diameter of our own planet, Earth…

2)  …This means that Earth can fit inside the Sun over a million times!

3) The Sun releases 400 million million million million Watts of power each second (the equivalent of the power used by the USA per year x 1,000,000) though the process of Nuclear Fusion*!

4) The energy released from the Sun’s core takes an estimated  20,000 years to travel to its surface…

5) …and takes a further 8.4 seconds to travel 150,000,000 kilometers to reach us, Earth!

6) The temperature of the Sun’s centre is 10,000,000,000 degrees Celsius, the same temperatures that scientists estimate we experienced only a second after the Big Bang!

7) The Sun was created 9 billion years after the Big Bang, only 0.72 billion years before the Earth was created!

8) The Sun’s core is actually 150 times denser than water, surprisingly!

9) The Sun is currently a Main Sequence Star, meaning the Sun is in it’s ‘middle-aged’ stage of its life!

10) Through the process of nuclear fusion, the Sun is creating elements from The Periodic Table of Elements up to Lead (everything ‘heavier’ can be created in a supernova, the death of a star)!

*See ‘Why Does The Sun Shine?’ to understand Nuclear Fusion. Coming Soon!