The Formation of the Solar System: Collapse of the Solar Nebula
“For a star to be born, there is one thing that must happen; a gaseous nebula must collapse. So collapse. Crumble. This is not your destruction. This is your birth.”
-N.T.
I have been sitting with the quote above for the past few days. Seeing as this is a blog post I thought it would be fitting to write about my topic, the collapsing of the solar nebula, over a short timespan. The quote inspired me to make use of the colored pencils I impulsively bought over the weekend.
Unsurprisingly, as I continued my research I continued to sketch. Some doodles translate concepts regarding the formation of the solar system well; others are a product of procrastination and therefore make less sense. Regardless, I thought I’d share some of my illustrations in order to help readers obtain a more candid view of my experience researching this topic.
I decided to stick with the balloon theme. The poor, unsuspecting girl lost her balloon (which represents the large, diffuse cloud of gas and dust our solar system derived from) because it began to condense. This cloud was composed of 98% Hydrogen and Helium gas, and the condensing process was most likely due to waves that were sent toward it by a nearby star exploding (a supernova), thus squeezing the gas and dust together. The solar nebula was a product of the gravitational pull between this gas and dust, consequently causing the cloud to begin spinning. The direction of the cloud’s spin can be explained by the collision of particles -- eventually, the cloud generated a preferred direction in the spinning increased in speed due to angular momentum. Once the general direction was established, the gravitational pull and increased spinning speed resulted in the solar nebula’s transformation from an oval shape to an elongated disk formation.
We've intrigued our girl, now. Following the formation of the disk, material began to accumulate in the disk’s center as the disk grew thinner and hydrogen atoms fused into helium. Some clumps that formed eventually matured into planets or moons depending on how close they were to the disk’s center. Due to the heat from the nuclear fusion, only rocks and metals could stand the high temperatures (like Earth!). Likewise, ices settled into regions on the outer edges of the disk (like Jupiter!) because the center was too hot for ices to condense.
Girl's eye reflects cooler (and redder), outer edges of the disk.
Girl's eye reflects hotter (and bluer) disk center, where nuclear fusion occurs.
The more the cloud condensed, the higher the temperature grew. The nuclear fusion eventually caused the disk’s center to grow so hot that it gave birth to our sun!
Well, it didn’t give birth exactly, but you know what I mean.
Finally, the formation of the star precipitated a stellar wind that blew the gas and dust of our solar system outward.
We can see above that there are four separate basic forces
at the present time. This graph attempts to show the process of “spontaneous symmetry
breaking", which is the breaking of the original forces into the four forces
as time increases and temperature and energy decrease.
We can explain these
forces between particles by using the concept of exchange particles. The
electromagnetic force and the gravitational force are commonly known forces
that are seen in everyday life. Electromagnetic forces combine the effects of
electrical charge and magnetism. This force exchanges visual photons, or
bosons, between charged particles. Gravitational force attracts any object that
has mass through the exchange of gravitons, which have not yet been detected.
The other two can be found inside the nucleus of the atom; they are both
nuclear forces, but there is one weak force and one strong. The weak nuclear
force is responsible for radioactive decay, which plays an important role in
nuclear fission, and uses the W and Z bosons as exchange particles. The strong force binds particles together to
form larger particles, such as holding protons and neutrons together to form
nucleons. It does this by exchanging gluons.
The photon, the exchange particle involved in the
electromagnetic interaction, along with the discovery of the W and Z bosons
provided the necessary pieces to unify the weak and electromagnetic interactions.
With masses around 80 and 90 Gev, respectively, the W and Z were the most
massive particles seen at the time of discovery while the photon is massless. The
theory suggests that at very high temperatures where the energies are in excess
of 100 GeV, these particles are essentially identical and the weak and
electromagnetic interactions were manifestations of a single force.
Grand unification refers to unifying the strong interaction
with the unified electroweak interaction. In the 1970's, Sheldon Glashow and
Howard Georgi proposed the grand unification of the strong, weak, and
electromagnetic forces at energies above 10^14 GeV. If the ordinary concept of thermal
energy applied at such times, it would require a temperature of 10^27 K for the
average particle energy to be 1014 GeV. This makes sense, as looking
at the first graph we see that the electroweak force and the strong force split
at a temperature of 10^27 K.
Physicists dreamt that there would be a unified theory in
which all known forces would emerge out of a single one in some way. Trying to
unify general relativity and quantum mechanics is so difficult because problems
arise in some situations which show that neither theory has all the answers. Look
at a black hole for example. Black holes are massive in density but infinite in
volume. They are so dense and heavy, gravity has compressed all of its mass
into a tiny point called a singularity. The center of a black hole is extremely
tiny and incredibly massive at the same time. So, we must use both general
relativity and quantum mechanics, however when these are applied together the
answers don’t make any sense.
String theory attempts to unite quantum mechanics and
general relativity so we can make sense of the universe on all scales. It does
this by suggesting that all subatomic particles are not singular points, they
are vibrating strings, similar to those of a guitar. The ‘notes’ are what give
rise to the different properties of atoms. When the vibration of the strings
change, different particles are created. Such a theory could help us learn
about gravity at the quantum scale, black holes or even the birth of our
universe!
However, a major problem with string theory is testing it. Many
of the tests require technology that we do not possess yet and may not for
hundreds, if not thousands of years from now, so there are many who do not recognize
string theory’s ideas.
One interpretation of string theory suggests that we may
live within a membrane, which contains our
entire universe and would exist in a higher dimension or “bulk”. In this higher
dimension, other membranes may exist which could contain their own universes.
Some theorists propose that our universe was
completely void of matter and energy, and that it possibly collided
another membrane in the bulk, possibly causing the big bang.
Tuesday, December 13, 2016
Dark Matter
All the matter that makes up every star, planet and dust cloud in the universe only composes close to 5 percent of all matter in the universe. What makes up the remaining 95 percent? 25 percent of all matter in the universe is in dark matter, while the remaining 70 percent is dark energy. What is Dark Matter and why does it make up so much of the matter in the universe? Beyond that, how do we even know it exists? Dark Matter is an enigma, but that doesn’t mean that Dark Matter doesn’t have a major impact on the universe. There are numerous occurrences that show the evidence of Dark Matter
What is Dark matter?
Dark Matter is a form of matter that is undetected, emitting little to no light. The reason we call DarkMatter “Dark,” is because Dark Matter consists of a completely unknown form of energy. Dark Matter was first proposed by Zwicky in 1933, he used it to understand the, “Large velocities of individual galaxies in the Coma Berenices cluster.”[1] There is not a definite answer to what Dark Matter is, but we can theoretically assume what it could potentially be, such as Weakly Interacting Massive Particles. All we know as of right now is that Dark Matter does exist.
Evidence of Dark Matter
Public Domain
Evidence for Dark Matter
In Spiral galaxies, such as the Milky Way, we can observe that unlike most objects orbital velocity, the orbital speed of spiral galaxies increase as it gets further away from the center of the galaxy and becomes constant once it is far from its center. From the orbital velocity equation (below) we see that the further away from the center of the galaxy, the slower the orbital velocity should be due to the radius. However, the galaxy is moving at a faster pace the further out, this means that the mass of the galaxy must be getting larger in order to counteract the increased radius. This gives us evidence that dark matter must exist as the matter of the spiral galaxy should not make the orbital velocity increase. Thus dark matter must be interacting with the spiral galaxy to speed up the rotation of the galaxy.
Another event which showed evidence of dark matter was when Nasa’s X-ray observatory took an image of two galaxies colliding, this collision caused dark matter to get separated from regular matter. The separation occurred because the collision caused regular matter to be slowed down while the Dark Matter moved at the same pace. The result is the following image.
PC: ASA/CXC/M. Weiss - Chandra X-Ray Observatory: 1E 0657-56
Dark Matter and formation of the Universe.
The reason why stars and galaxies are not uniform and appear very sporadically across the night sky is due to Dark Matter. When the Universe was first forming, it was, “homogeneous and isotropic.”[2] Meaning that all matter was equally distributed, but due to fluctuations within the universe, gravity soon pulled matter and dark matter together. These sections clustered together and eventually formed what will become galaxies. The evidence for this formation is through the Cosmic Microwave Background, where we see areas which appear hotter these areas are theorized to be the areas where dark matter and matter first interacted to form galaxies.
[1] Moore, Ben. “Dark Matter.” Philosophical Transactions: Mathematical, Physical and Engineering Sciences, vol. 357, no. 1763, 1999, pp. 3259–3276. www.jstor.org/stable/1353848.
[2] Tuttle, Kelen. "When space expanded faster than light." EarthSky. Last modified February 16, 2015. Accessed 12/13/2016. http://earthsky.org/space/when-space-expanded-faster-than-light.
The more the
human race learns about the universe the more questions that arise. The
ultimate fate of the universe is a prime example of this. A number of theories
have been created in hopes of explaining how our universe will come to an end,
but the truth remains that we don’t know for sure. In hopes of finding out our
fate, astronomers measured the density of our universe in order to further our
understanding of what might happen. Before calculating this, scientists figured
that there were three potential outcomes for the, universe each of them
determined by how tightly packed matter in our universe is.
Theory #1 “The Big Crunch”
If the
universe is denser than the critical density one day the universe will re-collapse
in on itself because of gravitational attraction. This would result in the
universe returning to the state in which it began, a singularity.
Theory #2 “The Big Freeze”
If the
universe isn’t densely packed enough that gravity wouldn’t be able to stop the
current expansion would expand forever creating an open universe. It would
never stop expanding, so eventually everything would cool down, and freeze.
Theory #3 “Critical Density”
The idea
that the universe is at the critical density meaning the expansion rate of the
universe would decrease until the end of time. Ultimately, everything would slow
down and eventually freeze.
Astronomers
measured the density of the universe, and found that our universe is currently
at the critical density. This discovery lead to the belief that theory #3 was our
ultimate fate, but after studying a distant supernova this idea was challenged.
Astronomers were able to look back in time at a white dwarf supernovae and discovered
that the universe is actually expanding at an increasingly fast rate. We call
the invisible force that pushes galaxies further away from each other dark
matter.
Eventually another theory called “the
big rip” arose in response to this discovery. The big rip says that the galaxies
will move faster away from each other that pressure caused by the expansion
will tear matter apart essentially ripping atoms.
The age old question of how will the universe end is still a very long way away from being answered. As time has gone on we have revised our guess of what will happen. Astronomers will continue to make observations and hopefully further understand what the end of our universe will look like.
The majority of evidence suggests that the universe was
created 13.7 billion years ago; it started from an infinitely dense and
infinitely small singularity. The universe expanded and created the first particles, elements and eventually stars, galaxies and planets. This
theory is called the Big Bang theory. The opposing, less supported theory is
called the Steady State theory. These two are the predominant competing
ideologies of how the universe began. The latter is aptly named, for it
suggests that the universe has been in a ‘steady’ state since the beginning.
There is much evidence that suggests the Big Bang theory is more suitable; this
blog will discuss the three most important pieces.
The first is called the Red
Shift. In 1912, it was determined that the majority of galaxies were moving
away from us, thus the universe is expanding.
When the universe expands the light expands with it, shifting the wavelength of light towards the red end of
the spectrum, hence the name ‘Red Shift’. The common analogy used to explain
this is the sound waves of a siren. When an ambulance gets closer and closer to
you the sound it makes becomes higher pitch; conversely when it moves farther
and farther away the siren emits a lower pitch frequency. The same is true for
light, except instead of pitch it changes color.
http://calgary.rasc.ca/redshift.htm
The second piece of evidence
is the distribution of elements. Physicists have calculated what the elemental
make-up of the universe might look like moments after a big bang, roughly ¾ hydrogen and ¼ helium with trace amounts of
a few other elements. This matches what has been measured in existing stars.
The third piece of evidence is called Cosmic Microwave Background Radiation, or
CMB. In the 1960’s Penzias and Wilson were building a radio receiver and came across
a source of excess noise. Eventually it
was realized that the noise was a result of leftover radiation from the big
bang. Nearer to the Big Bang this radiation was significantly hotter (thousands
of degrees K). Today CMB is only 2.725 degrees above absolute zero which is why
it shows up as microwaves on the electromagnetic spectrum.
If you are interested in the Big Bang Theory in a quick snapshot take a look at this video.
Our Universe is unimaginably old and its vastness can only really be studied and talked about on a very small scale, as to be truthfully understood. So enters the GUT or grand unified theory, a sort of simplified theory of everything, explaining the vastness of the universe today by breaking down the seconds after the Big Bang that created it. These few seconds after the Big Bang have been broken up into more simple categories by astrophysicists to explain the numerous things that were going on. There are 4 fundamental forces in the Universe, the strong force, the electromagnetic force, the weak force, and gravity, these forces govern the rules of the universe. Directly after the Big Bang it is thought all these forces were unified, into one overarching force. The same way electricity and magnetism were thought to be separate but were found to be the same force it's the same with these four forces, if we constructed a theory to describe this unification directly after the Big Bang, we’d technically have a theory of everything and how it works.
The Planck Era, the first era of the Universe, is possibly the only era in which these forces were all combined. It is theorized to have lasted from the first moment of the universe, until 10^-43 seconds after the Big Bang. Our current theories/models of physics can't really explain this time of the universe and they are effectively broken down and ineffective. By studying this time period we hope to construct all inclusive theories that make it possible to effectively discuss anytime of the universe.
The GUT Era comes next, although a little less speculative than the Planck era, a lot of what is happening during this time is also theorized. It's believed it began when gravity separated itself from the other 3 forces, with the strong, weak, and electromagnetic forces now their own separate force. This era ended when the strong force became its own force as well and it is thought that the strong force doing this is what brought about inflation.
The Electroweak era comes less and since it's farther away from the immense energy that resulted from the Big Bang a little more is known about it. Inflation is thought to have occurred during the Electroweak era, during which the universe expanded faster than the speed light and accounts for its vast expansion in size at that time. The observed large scale structure of the Universe is the result of quantum mechanical variations being blown up and carried out at this time of the Universe. After this era all four of the forces had become fully separated.
Although it was such a long time ago and may seem pointless to some there are many reasons why understanding how exactly the universe began is important to us today. The saying “Those who don’t learn about the past are bound to repeat it” can be used in parts to explain the importance of the research being done on GUT theory. Knowledge is power and the importance of knowing what made the universe is unrivaled in importance by anything else we could possibly putting money into. Although expensive we as a people should be willingly to spend limitless amounts of money to discover what made us, us and where we in fact came from not only as a species but universe.
A neutron star is often called “A Stellar Phoenix” because of its shared characteristics with a phoenix bird (http://www.space.com/22180-neutron-stars.html) . It is born only after its predecessor dies. In the case of a neutron star, the predecessor is a high mass star. When high mass stars die in supernovas, gravity forces their cores to collapse and the stars’ protons and electrons melt into each other. The combination of protons and electrons create neutrons, hence the title neutron stars.
After neutron stars have been created, they result in being city-sized objects with a mass that is about 1.4 times the mass of the sun. Neutron stars typically have a diameter of about 20 kilometers. Despite their small size, neutron stars are extremely dense. As little as a tablespoon of a neutron star would weigh as much as Mount Everest. If you want to think on even smaller terms, as little as a teaspoon would weigh a billion tons.
Since neutron stars are so compact, gravity on a neutron star is two billion times stronger than gravity on earth. Since the gravity is so strong, neutron stars can cause gravitational lensing. Gravitational lensing is when the gravitational pull created by the neutron star bends the light of another source. The bending of light can change the appearance of the light source. In the case of Neutron star, their gravitational pull is so strong that it can bend its own light, distorting its own image. If you would like to read more about it, you can visit: http://oneminuteastronomer.com/9237/gravitational-lens/
Neutron stars also tend to spin very quickly. The power that is given to the neutron star after the supernova explosion can cause the star to rotate up to 43,000 times per minute. The rotation speed of a neutron star gradually decreases in intensity over time.
If a neutron star is a part of a binary system, fascinating things can happen. To start off, one must know that a binary system is when there are two stars that are close enough for their gravitational fields to intermingle and cause them to orbit a shared barycenter. The habits of the neutron star change depending on the mass of its partner star.
If the second star is less massive than the sun: The neutron star will use its gravity to steal mass from the partnering star. The technical term for the resulting image of a neutron star being surrounded by a cloud of mass material from the the smaller star is an Roche Lobe. A Roche Lobe can be considered to have an hourglass shape as it encompasses both the partner star and the neutron star.
If the second star is up to ten times the mass of the sun: The neutron star will continue to steal mass from the partner star, just like if the star were smaller, but the transfer would not last as long.
If the second star is more than ten times the mass of the sun: Parts of the mass from the partner star will be transferred to the neutron star through stellar wind. Once transferred, the material can accumulate at the magnetic poles of the neutron star.
There are two different types of neutron stars. There are pulsars and magnetars.
A view from Earth tells us that pulsars appear to flicker. In reality, pulsars do anything but. Remember how a neutron star could gather material from a partnering star at its magnetic poles? These magnetic poles are not in line with the neutron star’s spin axis, making the poles appear to eject from opposing sides of the neutron star at an angle. Due to the high rotation speed of a pulsar and the angled position of the magnetic poles, the neutron star’s light appears to flicker when, in fact, the light is only rotating like a lighthouse. The flicking caused by the star’s rotation gives the pulsar its name because the light appears to “pulse.”
When the pulsar starts to die, the rotation speed decreases. Since the pulsar’s radiation is fueled by its rotation, the the amount of radiation emitted gradually decreases as well. When the pulsar stops spinning, it stops emitting radiation.
http://phys.org/news/2016-08-magnetars.html
Magnetars:
Even though neutron stars are predominantly composed of neutrons, protons tend to still exist, and since neutron stars are so dense, the small amount of protons can cause the neutron star to be magnetically charged. As a result neutron stars have magnetic fields. To give you an idea of the strength of the magnetic field that we are discussing, think of the Earth’s magnetic field of 1 gauss. A common neutron star has a trillion gauss magnetic field! And a common magnetar has a quadrillion gauss magnetic field! If a person were to get a little too close to a magnetar, the magnetic field could cause the person to dissolve! So, if you're ever getting bullied, don't call Magnetar, call a magnetar!
http://comicvine.gamespot.com/magnetar/4005-87958/ Picture of magnetar from:http://lucyconklin.com/pages/magnetar.html edited by: Tabreya Ryan
Magnetars can also cause starquakes. Starquakes take place when the magnetar’s surface is fractured. The fracture can lead to large bursts of radiation. These bursts are so large and disruptive that we can usually detect them on Earth, at least 10,000 light years away! To make things even crazier, astronomers don’t fully understand magnetars and are still trying to conceptualize the physics behind them. Though we don’t fully understand them, we do know that magnetars return to normal neutron stars after about 10,000 years. http://www.space.com/30263-paul-sutter-on-why-magnetars-are-scary.html
Random Facts About Neutron Stars
1.Some Neutron stars have their own planets orbiting them!
2.About 1,800 pulsars have been identified through the use of radio detection and 70 have been discovered through the use of gamma rays.
If you want to learn more about neutron stars, you can check out this really cool video:
