Big History Flashcards
How long ago was the “Big Bang”?
13.8 billion years ago (1st THRESHOLD)
Describe what happened minutes after the Big Bang, what was the state of the universe?
We can only speculate what happened before the Big Bang, but from about 10(-35) of a second after the moment of creation, our universe was something inconceivably tiny and hot was expanding at an unimaginable speed and cooling. There was only spacetime - matter (quarks and electrons) and energy (gravity, electromagnetism, weak + strong nuclear force) were indistinguishable. Quarks had linked up to form protons and neutrons. Within 3 minutes we had hydrogen and helium NUCLEI (not the atom!). For hundreds of thousands of years, the universe was a hot plasma of charged particles (protons - positive, electrons - negative). There was no structure or complexity.
Other entities and forces were formed that we don’t understand - “dark matter/energy”.
How many years did it take for the first 2 atoms to form and what were they?
380 000 years / Hydrogen + Helium.
(2nd THRESHOLD - Protons (+ charge) linked up with electrons (- charge) to form neutrally charged atoms: hydrogen and helium) + (a little of lithium, beryllium, boron)
Because the positive charges of protons are cancelled by the negative charges of electrons, atoms are electrically neutral, so electromagnetic radiation (of which light is just one form) could now travel freely through the universe without getting tangled in networks of electromagnetism.
What do Cosmologists describe as the “Dark Age”?
A cosmic “Dark Age” set in for the next 200 million years after the formation of the first atoms. This was a very slow and quiet expansion that spread more complex atoms and other materials throughout the Universe. The tiny particles drifted apart like a dense puff of smoke, but not uniformly.These first atoms were unevenly scattered and dispersed throughout space. 75% hydrogen (1 proton), 25% helium (2 protons) and 0.0000000001% lithium (3 protons), beryllium (4 protons), boron (5 protons).
What were the first ‘Goldilocks conditions’? When and how did this lead to the birth of the first stars?
13.4 billion years ago - tiny variations in the density of matter (atoms) throughout the universe were the FIRST GOLDILOCKS CONDITIONS for the formation of the 2nd threshold.
The key ingredients:
- matter
- gravity
- tiny differences (in temp and dispersion)
Newtons law’s states that strength of gravity increases with the mass of the objects involved and declines as the distance between objects increases. This means that gravity can magnify even the tiniest unevenness, because its power increases where matter is more concentrated.
Gravity packed slightly denser nebulae regions closer together so tightly that at the center, atoms banged together so rapidly that they generated heat and pressure. Eventually, they got so hot (3000 degrees Celsius) that protons and electrons split apart once more, recreating another plasma. Once temp reached 10 million degrees Celsius, protons OVERCOME THEIR POSITIVE REPULSION and fuse together (NUCLEAR FUSION) hydrogen nuclei fused together forming helium nuclei and are now held together by the STRONG NUCLEAR FORCE (through mesons). A part of them turned into energy as they did so - the theory of relativity, E = mc2, proves that matter can be converted into energy. The violent collisions that occur between protons in the core of stars convert their mass into HUGE amounts of energy, which lead to a huge release of heat from the center of the cloud (protostar) that prevented it from collapsing any further, a sort of furnace that pushes back against gravity and stabilizes in the process = THIS IS THE BIRTH OF STARS.
At the core of a star, hydrogen atoms slam together forming helium nuclei. Fusiom can continue until it has used its stores of hudrogen. This may yake millions or billions of years. Around the center is a radiation zone full of protons that will be fused when they sink down into the core. Plasma surrounds the center of the star.
Describe how were new elements created?
Stars are element factories, fusing elements like hydrogen, helium, etc to forge 25 of the most common elements like oxygen, carbon, nitrogen, iron.
Some stars explode (SUPERNOVAS) thus creating the rest of the elements known to man (3rd THRESHOLD).
Tiny imperfections. Little knots, wrinkles, and flaws will begin attracting nearby particles of matter. The clumps will grow, becoming more massive, and attracting more particles.
As these compacted clumps of hydrogen and helium grow in density, they’ll also heat up. Eventually, the clumps heat and compact to form a “plasma,” sort of a hot, swirling soup made up of free-floating atomic nuclei. This will form into giant balls called “protostars.”
Gravity squeezes the center of the protostars tighter and tighter. Their temperature rockets until they reach a flash point. And they “light up” as free-floating nuclei, slamming together with such intensity that they fuse into a new element. This process of “nuclear fusion” releases a tremendous amount of energy, presenting the Universe with a new complexity that is critical to the formation of galaxies, larger clusters, and superclusters.
Stars are very hungry. Burning at incredible levels, cranked to the extreme, a star will eventually consume all the hydrogen that powers its nuclear fusion. Then the star changes dramatically. The hot center shrinks. It grows even hotter. This intense heat and pressure creates other nuclear reactions, producing new, heavier elements — carbon, silicon, oxygen, and others, until it creates iron. Iron is heavy, highly stable, and cannot be fused further.
A catastrophic event begins. Lacking the outpouring of energy from its core, the star collapses. Its many outer layers fall inwards, in an enormous unbelievable avalanche of matter crumbling due to the pull of gravity from the dense core. They slam with unimaginable force into the star’s iron center, creating new elements. These new elements bounce off the iron core, hurtling outwards into space.
This is, in effect, the massive explosion and death of a star — a supernova — and the birth of new elements out into the cosmos.
In order for hydrogen and helium to fuse, temperatures need to be exceedingly high - this can only be found in ageing/dying stars. The death of a star begins when it runs out of hydrogen. Large stars have so much mass that they create enormous pressure and temperature. Those temperatures go up even higher when the star runs out of hydrogen. When that happens, fusion stops at the center and the star collapses like a burst balloon. The size of the collapse and the temperature that the collapse generates depends on the size of the star. If the star was big enough then the collapse is huge, creating such high temperatures that helium nuclei can fuse into carbon (to fuse 6 protons into carbon - 200 million Celsius). The star will expand again.
When the star runs out of helium, the process will repeat itself. The sun will collapse again, temp will rise and it will expand more. This time the star heats up and fuses carbon into neon, and oxygen, and silicone. This happens over and over to create nitrogen and eventually IRON (26 protons - 3 billion degrees Celsius).
When the star fills up with iron at its center, it can’t go any further and will collapse. If it’s a giant star, it explodes in a supernova and for a while shines like a galaxy and will produce enough heat to fuse ALL THE OTHER ELEMENTS of the periodic table that are then scattered throughout the galaxy. = CHEMISTRY IS BORN.
It has taken 3 steps to create chemical elements from which we are constructed. Hydrogen + Helium, the simplest atoms were created during the Big Bang. In their death throes, medium-large stars create elements such as carbon (6 protons), nitrogen (7 pr), oxygen (8pr), silicon (14 pr) and up to iron (26 pr). As dying stars throw off their outer layers, these elements are scattered through space, which is why, though not as common as hydrogen and helium, these elements are more common than others elements on the periodic table. The remaining elements were manufactured and scattered through space in supernova explosions. The first stars provided the energy flows and chemical ingredients needed to make even more complex entities like our Earth.
The 4th threshold is the formation of our sun and solar system - when was it formed and how did it happen?
4.6 billion years ago our sun formed like any other star, from a collapse of matter under the pressure of gravity, which was probably triggered by a huge supernova explosion in our region of the milky way. This supernova explosion also seeded and scattered the cloud with lots of new elements. So when new stars are formed they are surrounded by huge clouds of chemically rich matter. These clouds spin in different orbits around the newly forming star creating goldilocks conditions that are just right for elements to combine:
gravity, accretion and random collisions.
As the cloud collapsed it began to spin and flattened out to form a disk (like pizza dough) = protoplanetary disk/ proplyd. At its centre, it got hotter and hotter, until fusion began and our Sun was born. About 99.9% of matter in the proplyd went into the sun, but that 0.1% of leftover matter formed the solar system.
Define the process called “accretion”
Some atoms combine chemically to form new molecules, but atoms also clump together to form bigger and bigger lumps of matter. This process is called accretion. Eventually, accretion goes onto form entire planets.
How were planets in our solar system formed?
Since lighter elements are much more plentiful in the universe, many planets are mostly made up of hydrogen and helium. But because hydrogen and helium are so light, intense radiation from the sun can blast them away where they accumulated to form the outer gassy planets like Jupiter, Saturn, Uranus and Neptune. They contained 99% of the leftover matter. The tiny amount leftover from the residue orbiting near the sun are heavier elements: dust motes collide to create little rocks, ice particles collide to create snowballs that will eventually become asteroids/meteorites/comets. They are getting bigger and bigger and colliding with each other. Eventually, in each orbit you get large objects that sweep up (through their gravitational pull) everything else thats in their orbit. So eventually over a 100 million years, in each orbit you have a rocky planet.
The third rock from the sun = introducing Earth Beta.
What are the most common elements in the Earth’s crust and why is this important?
The most common elements of Earth crust are: oxygen, silicon, aluminium, magnesium, copper, sodium, carbon and iron (not hydrogen and helium). These planets represent new forms of complexity because they are more chemically rich and diverse than stars, which in turn could create even more complex entities like the first living organisms.
How many planets are in our solar system? Describe them.
The Solar System (fully formed 4.568 billion years ago) that we live in consists of a medium-size star (the Sun) with eight planets orbiting it. The planets are of two different types.
The four inner planets, those closest to the Sun, are Mercury, Venus, Earth, and Mars. They are smaller and composed mainly of metals and rocks.
The four outer planets — Jupiter, Saturn, Uranus, and Neptune — are larger and composed mostly of gases.
Of the four rocky planets, Mercury is the smallest, about two-fifths the size of Earth. Earth and Venus are almost the same size, while Mars is about half their size.
Pluto, orbitsfurthest from our Sun. However, Pluto does not count as a planet. It is smaller than Earth’s Moon. It orbits wayout in a belt of asteroids beyond Neptune (thoughPluto periodically comes closer to the Sun thanNeptune), and does not have enough gravity to clear the neighbourhood around its path. Therefore, it was downgraded to a “dwarf planet,” or a planetesimal.
What is the largest planet in our Solar System? Describe it
The “gas giant” JUPITER is the largest planet in our Solar System. Measuring by diameter, it is about 11 times the size of the Earth and its mass is more than 300 times that of Earth. In some ways, Jupiter is more like a star, or a “failed star” than like a planet since its composition is primarily hydrogen and helium. But Jupiter never heated up enough to start burning its hydrogen, as stars do.
What is the second-largest planet in our solar system? Describe it
The gaseous Saturn, the second-largest planet in the Solar System, is orbited by countless particles of ice and dust. This matter, in sizes varying from tiny grains to larger automobile-sized chunks, reflects light, forming Saturn’s trademark rings. SATURN’S rings seem poised to slice through its large moon Titan while the smaller moon, Enceladus, looks on.
How many Earth-like planets could there be in our Milkyway galaxy?
In the entire milky way galaxy, there could be up to 40 billion earth-sized planets orbiting their stars in the goldilocks conditions or life
What % of what elements make up our universe?
Hydrogen and Helium still make up 98% of the atoms in the universe.
