Multiverse

A prevailing theory in astrophysics is that of a multiverse. There are a bunch of different theories about this but they all revolve around the same basic premise. A multiverse is the idea of our universe being but one of a number of universes. You see this in science fiction a lot.

Quantum mechanics speculates in the ‘Many-Worlds’ interpretation that for every decision made there is a universe created for which the decision goes one way and for which the decision goes another. We have just simply flowed down one of those paths. In this instance you could say that the universe we exist in is constantly brand new and simply a duplicate of a parent universe.

Another idea is that we live in a hyper-dimensional universe for which our 3D universe is like a single page in a higher dimensional book. All other ‘universes’ are simply other pages.

Time Travel

Einstein says that as you move closer to the speed of light, time will slow to a halt for just you. This is the idea of time dilation. As you experience a normal rate of time, everything else will speed up around you, allowing you basically to jump forward into the future. It’s all part of the theory of relativity. Gravity also manipulates time. It bends the fabric of space-time around large bodies of mass, bending the local speed of it passing. We know this is a fact because it is this dilation which offsets clocks on board GPS satellites in orbit. Time is passing quicker on Earth’s surface because we are closer to the gravity well that the Earth is.

According to special relativity, going faster than light will theoretically reverse time. Let’s say you could travel faster than light, let’s pretend for a moment that is possible. You are standing at the end of a long hallway. You wave at the other end and then run 20 times faster than light to the other side and wave. You will be waving before the light from the other end actually hits you and you will technically be in 2 places at once. Let’s say you move 200 times faster. You could reach the other end and wave, the light of which will go back at the speed of light normally and hit you in the past, affecting causality. You could quite literally send yourself a message and alter your own events.

What has essentially happened, is time has inverted for you. You reach the speed of light and time reaches a standstill. If you go faster, the direction of time begins to invert itself. Going backwards is entirely theoretical as is most of the sci-fi science. Forwards in time is possible though.

Redshift, Blueshift and Doppler

The easiest way to explain this is with a police siren. When a police car that is blasting a siren is travelling towards you it sounds different than when it is driving away. The direction and speed of the car can manipulate the way the siren sounds to your perspective. The same process applies to photons of light. When galaxies move towards us, they appear more in the blue band of light. They become blue shifted. When galaxies move away they appear more in the red band of light. They become red shifted.

Heat Death

The Heat Death of the universe is intrinsically linked to the concept of Entropy. Entropy is disorder.

Let’s say you have a sandcastle made of millions of grains of sand. The grains in that sandcastle could be said to be in an ordered state. In this state it has a low entropy value. The sand however, has an uncountable amount of ways to be disordered. You could step on the castle and destroy the structure or you could wait for the wind to blow it away. The idea is that to put those atoms once more into that ordered state you need some very rare and specific conditions. The gains of sand could be blown back into a sandcastle by the wind but it is far far far more likely that this would not happen. When it is disordered it has a high entropy value.

The heat death of the universe is the idea that the universe is becoming more and more disordered. It predicts that at some point in trillions of years the universe will be so disordered that it will reach a state of “Maximum Entropy” and all thermodynamic processes (like atomic interactions, chemical bonds, fusion etc) will completely stop. At this point the universe would reach a point of thermal equilibrium and there would be nothing left. No stars, no planets, no black holes (if you believe Hawking), no matter of any kind, hence the completely black image.

Before this happens, scientists have predicted that there would be some interesting things that would occur. For instance, a theoretical type of star called an “Iron Star” might be produced due to cold fusion (if protons do not decay). An Iron star is exactly how it sounds, a gigantic cold sphere of Iron.

Higgs Field and Faster Than Light

Faster than light travel is staple of science fiction and the dream of many a young aspiring astronomers. The problem is that in normal acceleration (one point to another) it is scientifically impossible.

In the universe there is the Higgs Field. It exists everywhere. The Higgs Boson (not the god particle) is an extrusion of that field (much like an electron is an extrusion of an electromagnetic field). So imagine this line is the field. When scientists were trying to figure out how the universe works they created something call the “Standard Model”, which is kind of like the building blocks you need for a successful universe. They found out that, much like the dark energy/dark matter, the system didn’t actually work. They couldn’t figure out why a particle can have mass, so they assumed that there is an ever permeating field in the universe which ‘gives’ a particle mass.

This Higgs field is why we can’t travel faster than light. I’m going to oversimplify a little here. Objects with mass are kind of trudging through the snow of the Higgs field, whilst things like Photons of light can just fly overhead without a care. The Higgs field can fight you off at the value of infinity and the faster you want to trudge the more energy you need to keep putting in (acceleration). Theoretically to make the snow irrelevant, you would need to put in an infinite amount of energy. There is not enough energy in the universe to do that. In other words, there is no way to get rid of mass.

You see this all the time in particle accelerators. They can speed the particles up to 99.999% the speed of light, but that’s the limit.

Light, Neutrinos and other wave energies can travel at the speed of light because that is their constant speed. They are created at the speed of light and don’t have to trudge through anything to accelerate to it.

There are a number of theoretical ways to circumvent the issue though. One of the most interesting is the Alcubierre concept. In this idea, the craft you use to travel produces “exotic particles” which warp the fabric of space-time in front and behind you. You pretty much ‘surf’ on space-time. Because it is space-time which is moving and not the actual craft, you are not accelerating anywhere (you are technically stationary) and are free to travel as fast as you want. NASA is actually testing a device which utilizes this concept.

Other more fictional ideas include abstract concepts like wormholes, pocket realities, hyperspace, etc.

Pulsars-Neutron Stars

Pulsars are rapidly spinning Neutron stars. A Neutron star is a remnant of a large dead star, brightly glowing after the star has died. They are incredibly dense. We’re talking Mount Everest’s weight in a tea spoon sized portion of the star. They are also tremendously magnetic. The powerful magnetic field generates high energy radiation which spews out from the Star’s magnetic poles as massive jets of gamma radiation.

A pulsar, as mentioned spins really really fast. The rays of gamma radiation that we can measure from them seem to turn on and off as the direction of the ray points to us and away from us, making it look like it is pulsing in the night sky (hence pulsar).

Apophis

Named after the Egyptian anti-creator god and supposedly the bad guy from Stargate SG-1 (to whom its discoverers were fans), 99942 Apophis is an asteroid that passes by Earth around every 7 years. It is also big enough to cause some serious damage.

Back in 2004 it churned up a fuss because the chances of an actual collision were over 2% (which in terms of the size of the solar system, is a massive percentage). Scientists were worried the asteroid would pass through something called a “Gravitational Keyhole”, a well around 800 metres wide that would shift the Asteroid towards us on its next pass.

Obviously we’re still here. If it does hit us though, estimates have it producing an explosion 15 times the power of the most powerful nuke ever detonated (Tsar Bomba) surpassing the nuclear arsenal of the entire planet combined.

Black Holes

A Black Hole is an unimaginably dense point in space with a gravitational field strong enough to prevent the escape of electromagnetic radiation or matter of any kind. Think of it like a black ball. The ball is millions and millions of times denser than the Neutron stars mentioned above. The gravity that the dense matter creates bends space-time to a single point (the centre of mass for the ball). The gravity created by the immense mass bends the fabric of space-time stronger than anything else there is in the universe. The humungous gravity causes gravitational lensing and bends light. The gravity is so high here, that light simply cannot escape due to this intense bending. This makes the hole black. This is also what makes the hole so mysterious. We cannot measure anything about it because it exudes basically nothing. The only thing we can tell about a black holes is the effects it has on things outside of the ‘Event Horizon’ it creates.

The above image presents the ‘Event Horizon’. The border between what is black and what is not black is this horizon. Anything that goes beyond it will never come out, that is the basic premise. This does not show the actual size of the black hole however, merely the gravitational range for the zone of no-turning-back. The actual physical body of mass which causes this gravitational field is somewhere within. The size and physical appearance of the actual mass for the Black Hole is speculative. Most believe that the black hole is so dense it is basically a single one dimensional point in the fabric of reality.

If a dense star circles around a Black Hole, the star could get caught in a deadly orbit where its outer shell will be ripped from the core and converted into a brightly spinning disk. You can see that a feeding black hole is easy to spot. The star debris which is still fusing together matter lights up a disk around it and we can tell some characteristics of the Hole based on how it interacts with other things (such as how strong it is). As the debris settles out into a disk, the black hole gobbles up everything it can, and anything it cannot is spewed out into space in long spiraling jets.

Quarks

A Quark is a basic building block of matter. As far as we are aware right now, there are 6 “flavors” (yes that is the technical term) used to distinguish what energy levels they represent:

-Up

-Down

-Top

-Bottom

-Strange

-Charm

Quarks account for Mesons and Baryons and can be used to successfully describe, essentially, sub-subatomic particles. The names of the Quarks are fairly bizarre, as you can see. Things get even weirder when you go into detail about each one. Each Quark has three different “colors” for instance (red, green and blue) which have nothing to do with the actual physical color of the particle at all. Each one also has a corresponding “sign” to distinguish it being or not being an “anti-quark.” The reason for this nuts way of describing the different particles is that, for one, discoverers can name things whatever they want. Two, we have to call them something. The word ‘Quark’ is supposedly named for the word ‘Quack.’

In simplistic terms, you can think of Quarks like parts of a recipe. If you take one Quark of one “color” and sign and put it with other Quarks of other “colors” and signs you can start to make things like Protons and Neutrons. These then go together to build atoms. In antimatter, the signs of the quarks are reversed.

Antimatter

Antimatter is exactly how it sounds. It is matter with the same basic building blocks but the components of it have an opposite charge.

An atom is built from a nucleus that is normally comprised of a positively charged proton a neutrally charged neutron and is orbited by a negatively charged electron. The left part of the image shows this. An antimatter particle, as seen on the right, has all these parts but the charges are opposite. The positron plays the same role as the electron but it simply has a positive charge and the anti-proton has a negative charge.

When matter and antimatter collide they annihilate one another (annihilate is actually the technical term). When matter and antimatter meet, their mass actually gets converted 100% efficiently into energy (in the form of high energy photons). Apparently as long as energy is conserved, the collision can form a different particle/antiparticle pair instead of just photons. However, when trapped in magnetic fields in a lab, antimatter has shown to have basically the same fundamental traits as normal matter.

One of the biggest questions there is stems from anti-matter. According to the Big Bang theory, matter and anti-matter were created in equal uniform parts. As is already mentioned, when they meet they destroy one another. So why is there an overabundance of normal matter in the universe? Where is all the anti-matter? Clearly there was a preference for normal matter somewhere in the evolution of the universe at some point. via