Atoms: Proposed Building Blocks of Matter

   Thousands of years ago in Ancient Greece, a scientist named Democritus observed sandy beaches from a hilltop. He noticed that from afar, the beach appeared to be one continuous substance, but he knew that up close, the beach was composed of countless sand grains. In a stroke of brilliance, he reasoned that perhaps everything else was made up indivisible, innumerable balls like sand and deemed these theoretical objects, atomos, Greek for indivisible. Over the next few thousand years, atomic theory gained a popular foothold, yet scientists still doubted we would ever have the technology to actually observe these "atoms" as they are now called. Nowadays, atoms have become scientific fact and are accepted by the public. But are atoms truly indivisible as Democritus thought? And if not, what about the constituents that make atoms up? And what about those constituents' constituents?

   Most people are familiar with the idea that atoms are not really the fundamental building block of matter. Atoms themselves are made up of three subatomic particles known as protons (with a positive charge), neutrons (with a neutral charge), and electrons (with a negative charge). Atoms are arranged in a way that the protons and neutrons are clumped together in a dense core called the nucleus which the negatively charged electrons orbit.

In the picture of a lithium atom, the black balls are electrons, the red balls are protons, and the blue balls are neutrons

   Atoms are known to have certain properties based on their amount of a certain subatomic particle. These properties ultimately arise as elements, such as the lithium atom pictured above. The periodic table of elements is a recognizable chart among laymen as the table that lables what individual subatomic combinations culminate into what atom/element. But with atoms and subatomic particles, there came the question of what protons, neutrons, and electrons were composed of. So far, scientists have been unable to determine the composition of electrons, but it seems likely that these subatomic particles are essentially indivisible. As for neutrons and protons, scientists used particle accelerators to slam these atoms together at near light speed to see what was inside them. What was found were two new sub-subatomic particles: the quark and gluon. Quarks are broken up into six "flavors": up, down, strange, charm, bottom, and top. These names are all purely for labling purposes and do not correspond to if a quark is actually "strange" or "charmed".

The above illustration is represents a proton composed of two "up" quarks and one "down" quark. The squiggly lines represent gluons, the force carrying particles that keep quarks together

   Now to an introduction of quantum theory. In 1900, Max Planck, a physicist working on a problem concerning blackbody radiation, formed the hypothesis that energy was radiated and absorbed in packets, or quanta. While working on blackbody radiation, Planck developed his own constant called Planck's constant, which is the quantum of action in quantum mechanics. Planck is widely considered the father of quantum mechanics.

Max Planck, the father of the quantum theory

   Now that we have an introduction of atoms, the next post will be devoted to the actual behaviors in the atomic and subatomic realm. Keep checking back, ask me a question, become a member, or email me at superficialnickname@yahoo.com. Next post is on the real quantum mechanics! Until then, salutations!



Stellar Lifecycle: Death

   One day, stars will stop shining. The Sun will rise over the Earth, whatever state it may be in in five billion years, and it will have a final day as the Sun we know it. Low-mass stars like the Sun undergo fusion for a long time. In the later stages of their life when fusion has resulted in a core composed mainly of helium, the star will start to fuse hydrogen in the outer envelopes of the star. During this time, the star grows, it expands its diameter outward. When this happens in our own solar system, the Sun will swallow Mercury, Venus, and most likely the Earth. We will be on the inside of our Sun, our planetary surface either a burnt husk of what it was or the heat could melt the Earth and the planet simply dissipates into the newly formed red giant. Either way, no more Earth. But we will either be long extinct or long gone in the stars before that happens, so no worry. After this red giant phase, the star throws off its outer layers. The gas and plasma (super-heated, ionized gas) will be thrown outward to form a planetary nebula rich with newly formed elements. The core remains, and current stellar models suggest the remnant will be a dense white dwarf star. Over possibly trillions of years, this white dwarf will cool into a black dwarf, a truly dead star. It is a slow, rather boring process or these low-mass stars to die.

Artist's rendition of planets orbiting their white dwarf, the product of a once magnificent star

   High-mass stars have a far more exciting death. As mentioned in the previous post, these stars are massive enough to keep fusing up to iron. When iron is reached, heat is absorbed and the star collapses from its own gravity. The star implodes, fusing elements heavier than iron like uranium very quickly. Then, by a process still not completely understood, the star rebounds and creates a massive explosion in space. This explosion, called a supernova, is bright. Its luminosity is greater than the combined luminosity of all the stars in its own galaxy. In 1054 AD, a star's light that had gone supernova reached Earth and illuminated the night sky. It was bright enough to be seen in the daytime as well. These extraordinary events release gamma ray bursters, an event that would have catastrophic consequences for a planetary system near enough. Scientists believe Earth was hit by a gamma ray burster that rendered 99% of Earth's inhabitants extinct some time in prehistory, long before the dinosaurs. 

The image shown above is the Crab Nebula, it is the aftermath of the supernova witnessed in 1054 AD

   After the supernova, stellar cores of less than three solar masses become neutron stars. Basically a star composed of neutrons, they are incredibly dense. Their density is equivalent to sticking the mass of the Sun into the area of Manhattan. A teaspoon of neutron star material would weigh more than a battleship. Due to the law of conservation of angular momentum, the core rotates phenomenally fast, often time spewing material out of its magnetic poles. This is known as a pulsar and is akin to a cosmic lighthouse.

Pulsars are highly magnetized, so they have strong magnetic fields. The image shown is not what a real pulsar would look like

   The final fate for a stellar core of more than three solar masses is a black hole. Incredibly perplexing objects, it was only until the 70's before they were discovered in space. Black holes are a region of space-time that is so dense that light itself cannot escape the gravity. Everything has what is called an escape velocity. An escape velocity is the speed required to escape gravitational attraction. The Earth's is seven miles per second, meaning rockets that leave orbit must at least travel that speed. But a black hole's escape velocity is greater than the speed of light. If you will remember the posts about Einstein, it is impossible to travel faster than light, thus nothing escapes a black hole once it has passed through the event horizon. The event horizon is the point where the object chiefly becomes black. It is at this point that gravity is too powerful for light and photons are stuck in orbit around the black hole. At the center of a black hole is a singularity. A point where the laws of physics deconstruct and Einstein's theory of relativity fails. We do not yet know what occurs at the singularity, but it is one of the most sought out answers in physics. Black holes also grow as they "feed" on other objects. Their mass adds to the black hole's mass. The gravitational distortion of a black hole is so tremendous, that there is a point that to someone observing an object falling into the black hole, the object seems to stop. In fact, time itself seems to halt. But to the thing falling, time passes normally and it starts to stretch. Known as spaghettification, the objects is pulled apart, molecule by molecule, atom by atom, particle by particle and then is taken into the black hole's mass.

Artist's rendition of what a black hole looks like. Notice the distortion of the light around the object itself. This is called gravitational lensing and occurs when objects of high gravity distort light passing near them

   Stars form, stars live, stars die. One day, the last star will blink out of existence, but tonight when you look up and see just one, enjoy it. We are living during a period of the universe where stars are able to form and it will not last forever. Cherish the stars, for they died so their atoms created in their core could coalesce into you and I. We take stars for granted, but they fade into darkness one day. But enjoy them until then. 

   Hi all, I am going to be starting on quantum mechanics next post so we can build into subjects too complex to be explored with only relativity and classical mechanics. Ask questions about the post, criticize, praise, be indifferent to stars, whatever. Hopefully you come back and read. Subscribe to the posts and keep checking back for some quantum physics! Until then, salutations!

Stellar Lifecycle: Fusion

   Why do the stars shine? I have a very distinct and crisp memory of myself, at a mere age of seven, looking at the stars (and later, the Sun. By the way, that is not smart. My optometrist said it was likely my vision became so scarred because I looked at the Sun a bit too much.) and I would wonder What makes them shine? I knew the Sun was on fire, I knew it was flaming. But I also knew space lacked oxygen for fire to burn. This troubled me for a long time. Where did the Sun get its fuel from? When I was older, I received a book about stars. In the book, I learned stars were powered by a powerful force: fusion.

   As mentioned in the previous post, the early protostar first lights up when it becomes dense enough and under enough pressure, that the gas heats up and the hydrogen atoms and helium atoms start colliding into one another at super fast speeds. These collisions build up nuclei for heavier elements over time during stellar nucleosynthesis. The collisions also release huge amounts of energy. Stars are in a runaway state of constant fusion, they are basically one big hydrogen bomb. 

Deuterium and tritium (isotopes of hydrogen) combine into each other and form helium. In the process, energy is released, as well as a neutron

   

   So fusion creates energy for the star to shine. Not all stars burn their fuel in the same amount of time, it depends on the initial mass of the clump from which the star arises. Stars with higher mass burn their fuel more rapidly because they put more pressure at the core and fusion takes place at a more rapid pace. Lower mass stars last longer, usually billions of years (Like the Sun). The high mass stars in turn may only last a couple million years. During this time when hydrogen converts to helium, different stages of fusion must happen for the star to keep burning. Hydrogen starts to run low and different elements formed by early fusion slam into each other to make still heavier elements. Over time, stars forge these elements more and more. The higher mass stars get hot enough to sustain fusion up to the element iron. Then, iron begins to absorb the heat from the high mass star. All throughout its life, the star has been in a balance: it wants to blow apart from the heat released by fusion and it wants to collapse because of its own gravity. Iron absorbs that heat and suddenly the star begins to collapse. Gravity wins and the stars crushes down to an infinitesimally small point, a singularity. In this very short time, the star fuses heavier than iron elements, a last spurt of fusion. Then the implosion rebounds on itself and turns into an explosion. This explosion is known as a supernova. In it, the elements forged within the stars are thrown out into space, enriching it with elements that are heavier than hydrogen, helium, and lithium. Without this process, there would not be the necessary atoms to form people, planets, moons, comets, and all life in general. Carl Sagan was fond of saying "We are stardust." Truly, it seems we are children of the cosmos.

   In this post, I have outlined fusion. In the next post devoted to the stellar lifecycle, we will explore the deaths of stars and their stellar remnants. I have given a little hint of it in talking about supernovae, but I will be more detailed in the next post: Stellar Lifecycle: Death. Feel free to ask questions, share the blog with friends, or become a member. I'll post back soon, until then, salutations!

Her

   Hey, all, this post isn't about physics at all, it's just a little something for someone special to me. Feel free to skip it, but it'll show I'm not just a dry intellect interested in science.

   Seven months, seventeen days, six hours, and about forty minutes. That is how long we've been together. But it feels like, just perhaps, that time together, that chance meeting, was destined to happen. Since then, I have fallen, truly, deeply, very passionately, in love with....her. Some say she's just a phase. Some say she's one of many to come. But those people do not know us like we know ourselves. They have not been a part of this relationship. It seemed impossible for there ever to be a relationship. I say left, she says right. She looks up, I look down. But just as puzzle pieces fit together, a perfect fit where something fills the void, makes it complete, she does it for me and I hopefully do the same for her. Her beauty is truly unmatched by any other woman. She is a luminous woman, more luminous than the stars of the sky added together. I cannot help but to smile when I see her. Her hair flows, ever so graceful with a turn of her head. Does water even flow that way? Her eyes. Such...perfection. Shining so big, so bright. She never is disinterested when I talk about Cosmic Microwave Background Radiation, or never nods off when I lecture about Heisenberg's Uncertainty Principle. She simply says "I love you" in response. And those three words can part storm clouds in the sky, they can revive me from a depressed state, they can do amazing things. She is my other great passion in life. Next to physics, I'd gladly give up a career in physics and pursue a career as her husband. Secretly, I am always grateful when she makes me late for stuff by demanding that I do not leave, that I stay for another five minutes. It makes me feel wanted. She captivates me, she motivates me, she stirs up something previously unknown to me: love.

I love her.

   Thank you all for listening to the rambles of a guy in love. I'll be posting soon about fusion, but until then, salutations. And if you are her, I love you always.

Stellar Lifecycle: Formation

   Nebula are the nurseries of the stars. It is within these great cosmic clouds that stars form. Nebula were first formed after hydrogen and helium condensed into the first stars. These stars had an incredibly high mass, so they burned their fuel fast and died hard. Their death came in the form of a hypernova, showering the cosmos with the elements formed in the stellar core. After many generations of these high-mass stars, these heavier-than-hydrogen atoms mixed in with the clouds of hydrogen, helium, and trace amounts of lithium formed after the cooling of the big bang.

   Nebula are primarily composed of hydrogen and helium, but after the deaths of the first stars, they became flooded with elements like carbon, silicon, and iron. Within the nebulae, gas starts to clump together and get denser. Over time, the clump starts to give off energy from the friction of the atoms rubbing together and from the clump's own gravity pulling in the gas and putting it under pressure, making it hotter and hotter. This is the stage known as a protostar. Eventually, the accumulation of gas becomes hot enough to support fusion. In this process, the atoms race around and hit each other, releasing energy in the form of photons, or light. This is why stars shine. About 99% of the gas goes into the star, (or stars, as many solar systems have been found to have multiple stars) but the rest of the material goes into making planets like the Earth.

   So stars are born inside of nebula. All stars have their beginning inside these great clouds, all stars including the Sun. I will continue the next post with a more detailed explanation of fusion and its implications for the formation of us. I would like to apologize for my absence, I just went through another move and we were having difficulty setting up our WiFi. But I will be posting back soon with Stellar Lifecycle: Fusion! Until then, salutations!