The Big Bang and Consequent Formation of the Solar System

Danny Dale

Physics and Astronomy

University of Wyoming

Find this presentation online at

faraday.uwyo.edu/~ddale/teach/01_02/merav.ppt

This presentation was largely created by G. DennJanuary 29, 2002

The basic premise

The Universe, consisting of all space and all time, started for no apparent reason approximately 14 Gyr ago

The hydrogen and helium condensed to eventually make stars within galaxies (dense regions of stars)

Supernovae, and processing within red giant stars, created the majority of the heavier elements

Ejected material recondensed to form the Sun and Solar System

The earth cooled, life popped up, we started breathing air, etc.

Definitions

Cosmology: The study of the Universe as a whole

Cosmogony: The physical study of the origins and evolution of the Universe

Spacetime: the coordinate system of the Universe

What is spacetime?Spacetime is the combination of space and time, interrelated by the speed of light. Einstein showed that spacetime has certain transformation properties, and that simultaneity does not exist-it depends upon how one clock is moving relative to another.

Your point in spacetime can be set up as three space coordinates plus one time coordinate:

Latitude: 41°18' N; Longitude: 105° 15' W; Altitude: 7200 ft

Time: January 29, 2002, about 9:40 AM MST.

4-D spacetime coordinates

The Big Bang

The Universe started about 14 billion years ago, in an event called the Big Bang. The Big Bang was not an event: space and time were created at that moment. The Universe originally was infinitely hot and dense. Since then, the Universe has grown and cooled.

Whats the evidence?a) The recession of galaxiesb) Cosmic Microwave Backgroundc) Hydrogen/Helium abundances in the early Universe

Act I: Milky Way, Galaxies,and Hubbles Law

Galaxies contain billions of stars and huge clouds of gas and dust.Our Sun is 25,000 light years from the center of the Milky Way galaxy.

Other GalaxiesGalaxies come in three major classifications:

Elliptical, Irregular, Spiral.

Galactic Distribution Galaxies in space arenot regularly distributedbut clump together in filaments and sheets, separated by vast nothingness called voids.

The spectrum of the Sun

Things that are approaching you are said to be blueshifted, but are not necessarily blue.

Things that are receding from you are said to be redshifted, but are not necessarily red.

This is called the Doppler Effect.

The Doppler effect

The blue end of the spectrum is at short wavelengths, high frequencies.

When something is blue-shifted its spectrum gets transformed into one with higher frequencies. When something gets red-shifted its spectrum gets transformed into one with lower frequencies.

The Doppler effect works with sound waves also.

However, there is no sound in space! Light waves are either blue- or red-shifted.

Gotta little somethin' in the ovenAs raisins in an expandingraisin bread are all movingaway from each other, thegalaxies are all recedingfrom each other in an expanding universe.

Hubbles LawEdwin Hubble noted that almost ALL galaxies hadredshifts and NOT blueshifts. The redshift is proportional to the distance. From the Dopplereffect, this indicates thatthe galaxies are recedingfrom Earth. The best explanation is that the Universe is expanding.

The fit for the graph above says that for v = Ho d

Ho = (67 ± 15) km/s/Mpc. H

o is known as Hubbles constant.

Act II: Blackbody RadiationEverything above absolute zero can release energy via thermal emission. The characteristics of the emission depend solely upon the TEMPERATURE.

Wiens Law: Hot things are bluer than cool things.

The Universe is at about 2.7 K

Penzias and Wilson

Spectrum of 2.7K blackbody and radio astronomy data

What does the future hold?

If the Universe has enough mass then gravity will pull it back together in a Big Crunch. If not, then space will forever grow.

Flat and Curved SpaceA flat space has straight geodesics and a curved space has curved geodesics.

These are two- dimensional examples of curved and flat space. We cant imagine a curved three dimensional space.

(Ok, I cant.)

But we can test for it

By using principles of geometry we can test the curvature of a space.

Whats the curvature of space?

There are three options:

Flat (below)

Curved Positive (corner)

Curved Negative (right)

Science Magazine's Breakthrough of the Year (1998)

Assuming that Supernovae Type Ia are "standard bombs," then the evidence points to an accelerating Universe (supporting something Einstein hypothesized and then later rejected as his "greatest blunder").

fain

ter

farther

BOOMERanG evidence...Ballon Observations of Millimetric Extragalactic Radiation and Geophysics

These data, which attempt to show the isotropy of the universe, describe how sound traveled through the early universe.

The conclusion is that the universe is FLAT.

We think we are converging to an answer

Physical tests of the curvature are improving. The supernovae and cosmic background data point to a flat Universe that is filled with 30% matter and 70% "dark energy."

Dar

k E

nerg

y F

ract

ion

Matter Fraction

Which means it will expand to ¥

Which means that some being somewhere else will give the same lecture, except that it will be wearing a suit and tie and have purple hair.

Act III: Chemical EvolutionIn the first few minutes of the Universe, some of the elements formed.

@ t = 10-6 s:

The Universe was at T =1013K and filled with high energy gamma rays, which can form massive particles in a process called pair production.

Two photons come together to form a

matter-antimatter pair

Matter-antimatter annihilation

E = mc2 governs this phenomenon!

The cooling UniverseAs the Universe cooled, fusion of the heavier elements took place. The result was about 76 percent hydrogen, 24 percent helium, and traces of Lithium, Beryllium, and Boron.

When did stars form?

When looking as far back as possible, we see evidence for faint blue galaxies at a time of about one billion years after the big bang. These original stars were composed of the primordial elemental abundances.

Processing in SupernovaeA supernova is an explosion that occurs when a star can no longer support itself against the force of gravity. Normally, hydrostatic equilibrium is maintained: gas pressure and gravity find a balance.

Stars convert hydrogen into helium and other heavier elements. This fusion process releases energy. When a star runs out of fuel, it starts to collapse upon itself, which releases gravitational energy.

This can either a) heat the star up so it can burn other fuels (e.g. three helium atoms form one carbon) or b) if the star is really out of fuel, it collapses suddenly, releasing an incredible amount of energy (brighter than the host galaxy!). This explosion drives nuclei into each other in a rapid set of reactions.

Collapse of the core of a Red Giant and shock wave (that forms elements)

Molecular Clouds

After many generations of supernova processing, the Milky Way had enough heavier elements to form rocky planets. The Sun formed in a molecular cloud (now long gone) similar to the next image taken with the Hubble Space Telescope:

A Star forming region:M16

This cloud is about 30 light-years across. The stars are formed in the EGGs. Newly hatched stars are visible in the vicinity.

Current chemical abundances

This is by number, not mass

Solar Nebula: Infalling Material

Rotating DiskThe planets form out of the rotating disk surrounding the protostar.

Beta Pictoris

Tiny interstellardust grains serveas condensationnuclei--platformsto which otheratoms mayattach, forminglarger andlarger balls ofmatter.

1000

AU

Condensation vs. Temperature

Heavier elements tend to condense at higher temperatures than the lighter elements. This has a ramification for the structure of the Solar System.

The planets condensed at different temperatures

One of the planets has life

End of Presentation

Life in the UniverseSummary:

The Universe started about 14 billion years ago as an infinitely hot and dense dot, and has grown larger ever since; this Big Bang is evidenced by the recession of galaxies and the 3K background. About a billion years after the Big Bang, galaxies formed out of the mostly hydrogen Universe. Stars and the subsequent explosion of massive stars converted hydrogen into helium and other, heavier atoms. About 5 billion years ago, the Sun and solar system were formed out of the material that had been processed many times by generations of star formation and supernovae (stellar explosions which create heavy elements). About 3.8 billion years ago, the Earth was cool enough to have liquid water. Blue green algae formed and took the carbon dioxide out of the atmosphere. Life was single-celled until 700 million years ago (about three solar orbits around the galaxy), and it evolved in the water. When the ozone layer formed, it blocked UV light so land-based life could survive. Mammals are about 200 million years old, and apes (homo sapiens) arrived about 500,000 years ago. I showed up 31 or so years ago, and am the acme of evolution.

How to define life?

The universe may or may not be teeming with life, but this part of it certainly is. We will not be discussing the origins and evolution of consciousness, only how science defines life. Life needs a definition, and since it is difficult to define, we'll just set up some rules and try to adhere to them. Life A) comes in cellular form B) has a genetic system to reproduce C) has a metabolism D) evolves in a generational form.

Life on Earth Life on Earth contains amino acids and nucleotides, which form proteins and nucleic acids. The amino acids in life are left handed only: no right handed form is known, but in theory could be produced. Life needs water and is carbon based.

Glycine

PhenylalanineA (a nucleotide)

Origins of Life The origins of life on Earth may (or may not) come from one of two sources: primordial soup or extraterrestrial.

Primordial Soup: There is a plethora of organic (meaning carbon based, not pesticide free) molecules in the universe,and many of these could be on the primordial Earth. Given enough time, and enough heat, pressure, electric discharges, mixing,whatever, the simple molecules may have formed more complex ones. Although it is unlikely that any one event produce this,over a billion years, the number of possibilities for events to occur is huge, especially on the short timescales with whichchemical reactions occur (microseconds). The Miller-Urey experiment tried to reproduce these conditions.

Panspermia is not a dirty word

Panspermia: the theory that life arrived on Earth after it formed elsewhere, either within or out of the Solar System. The spaceships were comets and asteroids and the seeds were freeze-dried bacteria. The Mars rock ALH84001 spurred a new interest in panspermia. As Lou Frank once told me, "It's a plausible theory but there are no data." However, we can test panspermia by looking at amino acid ratios in space, mining comets with microscopes looking for bacteria, etc. For example, if STARDUST, a mission to Comet Wild-2 comes back with comet bits that have bacteria with left-handed amino acids, that would be very good for panspermia.

The Acme of Evolution?

Geodesics: the shortest paths

The shortest path between two points is said to be a geodesic. In space-time, light travels from A to B along geodesic paths.

Information travels at or below the speed of light

This is a spacetime diagram. An event that happens here and now can only be detected at a distant plate when the light (or gravity) reaches it.

If you are at point P, then your possible past comes from the blue region below, and your possible future lives within the yellow part above. These paths are said to be timelike. Impossible paths are said to be spacelike.

Travelling to the nearest star

Life is so precious.

This deep-fried chicken headwas recently found in anorder of McDonaldschicken wings.

Good thing she didntorder the pork chops.