How the Universe got its How the Universe got its SpotsSpots

The Big Bang

GoalsGoals

• Where did the Universe come from?• Where is it going?• How can we see the past?• How can we learn about the future

from seeing the past?

Can you accept & Can you accept & understandunderstand

concepts like these?concepts like these?• Nuclear reactions and the weak interaction Nuclear reactions and the weak interaction the rules the rules that govern the universe are foreign by everyday that govern the universe are foreign by everyday standards, but standards, but there are still rulesthere are still rules; we can know ; we can know them in detail, and use them to study other them in detail, and use them to study other phenomena.phenomena.

• Dark matter and dark energyDark matter and dark energy the universe is the universe is controlled on large scales by controlled on large scales by entities unlike usentities unlike us; there ; there is no problem with this – it’s exciting, and probably is no problem with this – it’s exciting, and probably solvable.solvable.

• Big bang theory Big bang theory the universe is vast in space and the universe is vast in space and time and evolves over time like our world does, but it time and evolves over time like our world does, but it is is notnot beyond our ability to measure with precision! beyond our ability to measure with precision!

• Origin and evolution of life Origin and evolution of life we appear to be we appear to be part of a part of a cosmic systemcosmic system, organized and tweaked chemically on , organized and tweaked chemically on Earth in a way that could have happened elsewhere Earth in a way that could have happened elsewhere too.too.

The Future from the Past

• Is the Universe:– Slowing down?– Speeding up?– Staying the same velocity?

• In the past, was the Universe:– Going faster?– Going slower?– Going the same velocity?

• The Universe is a time machine.

Time line: Cosmic Soup, Radiation Era, Matter

Dominated Era

The Big Bang• Big Bang: the event from which the

Universe began expanding.• Into what did the Universe expand?• Where was the Big Bang?• Where is the center of the Universe?

Consequences• If everything is moving away from us and things farther are

moving faster• Then the Universe is expanding!

This doesn’t mean what you are probably thinking . . . .

Expanding Universe• Space itself is expanding, not matter flying apart

within space.• Examples:

– dots– rubber band– raisin bread– ants on a balloon

It does not mean we are at the center of the Universe

every part of the Universe sees everything moving away from it

Looking Back in Time• Remember it takes time for light to

reach us– travels at 300,000 km/s– So we see things “as they were” some

time ago• The farther away, the further back

in time we are looking– 1 billion LY means looking 1 billion

years back in time• So the greater the redshift, the

further back in time– redshift of 0.1 is 1.4 billion lightyears

which means we are looking 1.4 billion years into the past

Big evidence for Big Bang

• 1992 COBE satellite :Cosmic Background Explorer satellite : Background radiation

• “it’s the discovery of the century, if not for all time…” Stephen Hawking

• “the handwriting of God…” Dr. George Smoot, astrophysicist, there was a definite beginning to the universe

Galactic Redshifts• Edwin Hubble (1889-1953) and colleagues

– measured the spectra (light) of many galaxies– found nearly all galaxies are red-shifted

• Redshift (Z)

(Doppler effect) Z = v/c(for speeds approaching c,

we’ll need a relativistic version of this equation.)

rest

rest

-

= observed Z

Andromeda galaxy

Z = [(1+ v/c)/(1+ v/c)]1/2 - 1

Do you know what Red Shift is?

RedshiftQuasars & Cosmology

Department of Physics, Applied Physics & Astronomy, RPI

In relativity the space between the galaxiesis expanding.

Hubble’s Law

• Galaxies are moving away from us.

• The farther away the faster they go.

• V = Ho x D

Expanding Universe

• If galaxies are all moving away, then at some point they were all much closer.

• Hubble’s Law implies the Universe is expanding.

Look back Time• We see everything as it once was.

Young Old

Age of the Universe• Since all galaxies are moving away

from us, how long has it been since all galaxies were together?time = distance / velocityvelocity = Ho x distance

time = distance / (Ho x distance)

time = 1/Ho

“An expanding universe does not preclude a creator, but it does place limits on when he might have carried out his job.”-Steven Hawking, A Brief History of Time

But does it give us enough time?

• Agnostic biophysicist Dr. Harold Morowitz wondered…– Suppose you break all chemical bonds in

the simplest organism (a bacteria) and put those atoms under ideal chemical conditions

– Question: How long would it take for it to reassemble?

Answer: 10100,000,000,000 years!

• Written out completely, that would be:1,000,000,000,000,000,000,000,000,000,

000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,… (on and on)

a thousand sets of Encyclopedia Britannicas filled with zeros!!

So, is it feasible?

• 10100,000,000,000 yrs is impossible because…– Hydrogen atoms would decay after [~1033 years]

500,000,000,000,000,000,000,000,000,000,000 years

– Heat death of the universe will occur at 80,000,000,000 years

– Big Bang restricts the age of the universe to be <50,000,000,000 years

We clearly don’t have enough time for atoms to randomly combine together to form even a simple bacteria!

Hubble Space Telescope

• Use HST to find Cepheids in other galaxies.

Luminosity and Distance

• Brightness goes as 1/D2.• Move light:

– 2x farther away, one quarter as bright.– 3x farther, one ninth as bright– 10x farther, one hundredth as bright.

• If you know:– How bright it looks– How bright it SHOULD be– You know how far away it must be.

• Standard candles yield distances!

60s

50s

Baby Boomer Universe

40sFarther away we look, further back in time we see!

90s

80s70s

What We See

V

Distance (Lookback time)

Present Past

Are We Slowing Down?• In our experience,

things slow down over time.

• Is the Universe slowing down at all?

• Plot distance versus velocity.

• Use supernovae as “standard candles.”

– Distant supernovae (large lookback time).

Accelerating

SlowingV=HoD

Are We Slowing Down?

• Unseen mass making stars move fast:

Dark Matter• Unseen energy

accelerating galaxies:

Dark Energy

Slowing

Accelerating

We are not made of the same type of matter as most of the Universe!

The End of the Universe

• Will the universe expand forever?

• Depends on the density of the Universe.

• Too big: Big Crunch– Closed Universe– Bound Universe

• Too small: Big Freeze– Open Universe– Unbound Universe

Concluding comments

• "Astronomy leads us to an unique event, a universe which was created out of nothing and delicately balanced to provide exactly the conditions required to support life…the observations of modern science seem to suggest an underlying, one might say, supernatural plan…“ [Nobel Laureate Arno Penzias ]

• “the origin of life appears to be almost a miracle, so many are the conditions which would have had to be satisfied to get it going…” [Nobel Laureate Francis Crick]

Some references• John D. Barrow and Frank J. Tipler, The Anthropic

Cosmological Principle (New York: Oxford University Press, 1996)

• J. P. Moreland (ed.), The Creation Hypothesis (Downers Grove, Illinois: InterVarsity Press, 1994)

• Charles B. Thaxton, Walter L. Bradley, and Roger L. Olsen, The Mystery of Life’s Origin: Reassessing Current Theories (Dallas: Lewis and Stanley, 1992)

• Robert Shapiro, Origins: A skeptic’s guide to the creation of life on earth (New York: Summit Books, 1986)

• www.origins.org - www.arn.org - www.leaderu.com