# Presentation: 336180

## WHAT POWERED THE BIG BANG?

- WHAT HAPPENSAT THE EDGEOF A BLACK HOLE?

- WHAT ISDARK ENERGY?

- National  Aeronautics andSpace Administration

***Presented by Dr. James Lochner (USRA & NASA/GSFC)***

## Beyond Einstein

- Einstein’s Predictions
- Expanding Universe
- Black Holes
- Dark Energy
- Evidence for those predictions
- Lingering Questions ...
- What Powered the Big Bang?
- What Happens at the Edge of a Black Hole?
- What is Dark Energy?
-  ... And How We’ll Answer them
- LISA
- Constellation-X
- Implications for Your Students

## Einstein changed the way we think of the universe:
 The speed of light is the ultimate speed limit.
 Time passes more slowly for observers traveling at high speeds or near a massive body.
 Light rays can be bent passing near a massive body.

-  The speed of light is the ultimate speed limit.
-  Time passes more slowly for observers traveling at high speeds or near a massive body.
-  Light rays can be bent passing near a massive body.

**Einstein & Our Universe**

- These predictions have been confirmed by observations.

- Einstein’s theories also made three startling predictions:
- The expansion of the Universe (from a big bang)
- Black Holes
- Cosmological Constant
- (acting against pull of gravity)

**Notes:**
Expanding Universe and Black Holes - predicted from General Rel.

Cosmological Constant - something to keep the universe steady (ie. From contracting under gravity), since there was no evidence for an expanding universe in 1916-1917.

## Evidence for the Expanding Universe

- We know about Expanding Universe & Big Bang from:
- Hubble’s discovery of red-shifted galaxies.
- Penzias & Wilson discovery of 3 K background.
- Abundances of the light elements.
- Big Bang alone doesn’t quite produce the universe we see.

-  Inflation produces a flat universe.
-  A growth spurt that stretches sub-atomic scales to astronomical scales.
-  Produces the fluctuations that lead to galaxies.

**Notes:**
We know about Expansion of Universe because 
Hubble’s discovery of redshifted galaxies
The 3 deg microwave background
Size of primordial lumpiness (0.001% variations in CMB)
Abundance of light elements
But the Big Bang alone also does not explain why universe is so large and so uniform (physically disconnected regions must expand at same moment and same rate), nor the origin of the lumpiness in distribution of matter that produces stars and galaxies.

Inflation - produces a flat universe.  It’s a growth spurt that stretches sub-atomic scales to astronomical scales. Homogeneity from the small scale.  But it also produces the fluctuations that lead to galaxies.
Re: Inflation explains how the universe got so big and so uniform. Inflation uses the vacuum energy (possibly same as for dark energy)
Inflation occurs at 10^-45 to 10^-32 s, and expands universe by factor of 10^50

## Evidence for Black Holes

- Black holes in 3 flavors
- Stellar (5 - 15 solar masses)
- Evident in X-ray Binary Systems
- Massive (Million solar masses)
- In center of galaxies
- Intermediate (Thousand solar masses)
- Within galaxies, but not in center
- Abundant Observations and Evidence
- We measure masses (e.g from binary systems).
- We observe radiation from gaseous disks surrounding the black hole.
- We see effects of strong gravity on nearby matter.
- First evidence for frame dragging and black hole rotation.

## Evidence for Dark Energy

- Dark Energy revealed itself in a survey of supernovae in the late 1990’s.
- We can use certain types of supernovae to determine distances to galaxies.
- We then compare those distances with the galaxy’s velocity.

## 1. Create a White Dwarf

**1. Create a White Dwarf**

**Notes:**
Slide 1 of 5 about Type 1a supenovae.  Big Idea: setting the stage for the supernova - creating a white dwarf.

There are different types of supernova, but the type we are interested in comes from a star like our Sun.  When the Sun runs out of its nuclear fuel in about five billion years time, it will go through a beautiful death ritual, shedding its outer layers in a blaze of color while its inside squeezes down into a dense white hot ball about the size of the Earth. This ball, aptly named a white dwarf, is where the story ends for the Sun, but not so other white dwarfs.  About 2/3 of all stars in a galaxy live in pairs (called binaries), a union that becomes dangerous when one of the pair turns into a white dwarf.

This image shows the Ring Nebula, Messier 57, with the white dwarf remnant at its core.

## 2. Dump more mass onto it

**2. Dump more mass onto it**

**Notes:**
Slide 2 of 5.  Big Idea: setting the stage for the supernova - white dwarf binary

About 2/3 of all stars in a galaxy are binaries. One star may run through its life cycle faster, becoming a white dwarf while the other star continues to shine normally.  This is true of the brightest star in the sky, Sirius, which has a faint white dwarf companion.   The white dwarf is greedy, and if the orbit of the white dwarf and its companion is close,  the white dwarf’s strong gravity begins to tug the outer layers of hydrogen gas from the companion and wrap the gas around itself, in the process creating a ticking time bomb. 

This artists’ impression shows a star-white dwarf binary system.  The two objects are close enough that the gravity of the white dwarf strips the outer hydrogen envelope off of its companion, spinning it into a flat disc because of white dwarf’s  rapid rotation.  The gas in the disc will eventually accumulate on the surface of the white dwarf creating a dense hot hydrogen atmosphere.

## 3. Until it explodes

**3. Until it explodes**

**Notes:**
Slide 3 of 5.  Big Idea: Supernova

The hydrogen layer grows, getting hotter and hotter, until at a critical temperature the bomb goes off – a thermonuclear explosion as bright as a billion stars, and a flash that can be seen across the observable universe.  Because the process is identical for each white dwarf supernova, the event has a predictable, and reproducible, brightness.  

A type Ia supernova  was seen in our own galaxy by Johannes Kepler in 1604, five years before the invention of the telescope.  This image is a composite of observations from three space telescopes, Hubble (yellow), Chandra (blue and green) and Spitzer (red) of the remnants of the star Kepler saw in the sky four centuries ago. The ball of debris is now about 8 light years across and still expanding.

## 4. Observe it in a distant galaxy 

- .....and can be seen in galaxies across the universe.

**4. Observe it in a distant galaxy***** ***

**Notes:**
Slide 4 of 5.  Big Idea: Supernova

A supernova can shine as bright as a billion stars for several days, rivaling an entire galaxy of stars.  This image shows a type Ia supernova  explosion in the galaxy NGC 4526. Because the explosion is just a point of light in the sky looks like a star. The processes and conditions that create this type of explosion are effectively identical for each white dwarf supernova, so the event has a predictable, and reproducible, brightness.  This makes them ideal distance indicators - the fainter they are the further they are.

By measuring the brightness of the supernova flash in NGC 4526, the distance to the host galaxy can be calculated.  Note to the presenter: a discussion of how this distance is determined (I.e. how we know it is “further away than it should be”) is not required, but if asked, you can use the comparison of a flashlight. This type of supernova has a known brightness (like a flashlight with a certain watt bulb) and can only be that bright. Just as a flashlight shining from further away appears dimmer than one nearby, measuring the light from this type of supernova tells scientists how far away it is.

## Evidence for Dark Energy

- SN Ia are more distant than expected.
- Spacetime has expanded more than expected.

**Notes:**
See Perlmuter, Physics Today, April 2003
Redshift measures the expansion of the universe (since the cosmic expansion also expands the wavelength of light)
“By the time the light reaches us, the spectral wavelength  has thus been redshifted by precisely the same incremental factor z o  by which the cosmos has been stretched in the time interval since the light left its source. That time interval is the speed of light times the object's distance from Earth, which can be determined by comparing its apparent brightness to a nearby standard of the same class of astrophysical objects.”
Initially wanted to measure the the deceleration of the expansion. “Because that deceleration rate would depend on the cosmic mean mass density m, we would, in effect, be weighing the universe. If mass density is, as was generally supposed a decade ago, the primary energy constituent of the universe, then the measurement of the changing expansion rate would also determine the curvature of space and tell us about whether the cosmos is finite or infinite. “
~~~~~~~
Discovery in 1998
Discovery via Type Ia supernovae (white dwarfs blowing up)
  - used to study the expansion rate of the universe at earlier times.
In decelerating universe, supernovae would be brighter (i.e closer) than their redshifts would indicate.
These SN appear more distant than expected.  I.e. they are fainter (I.e. farther) than their redshifts would predict.  [Perlmuter - you have to look back further in time (ie greater distance, fainter SNIa) to find a “given integrated expansion (redshift)”
  - expansion of universe is speeding up, not slowing down!
Flatness of universe and its known makeup leave 65% as “unknown” - Dark Energy fits into this slot.

## Dark Energy and the Universe

**We do not know what 95% of the universe is made of!**

**Dark Energy and the Universe**

- Flatness of Universe and amount of known matter (and dark matter) means *dark energy *makes up 70% of the Universe

## Completing Einstein’s Legacy

_**BIG BANG**_
**What powered the Big Bang?**
_**BLACK HOLES**_
**What happens at the edge of a Black Hole?**
_**DARK ENERGY**_
**What is the mysterious Dark Energy pulling the Universe apart?**

*Einstein’s legacy is incomplete, his theory fails to explain the underlying physics of the very phenomena his work predicted*

**Notes:**
Re: these are questions for us (with expectation that its high school and college kids who will ultimately answer them)

## What Powered the Big Bang?

- Inflation
- (Big Bang plus
- 10-34 Seconds)

- Big Bang plus 300,000 Years

- Big Bang plus
- 14 Billion Years

**Gravitational Waves Can Escape from Earliest Moments of the Big Bang**

- Now

- gravitational waves

- light

## What Powered the Big Bang?

- Inflation period and from “phase transitions”
- may be detected directly.
-  Free quarks becoming bound into protons, neutrons, etc
-   Decoupling of the Electroweak and Strong forces
- Wavelength of the Gravitational Waves gives size of Universe at that time.

**What Powered the Big Bang?**

**Notes:**
Sources of Grav. Waves from the Big Bang
Various phase transitions: 
Free quarks -> bound quarks at 10 microsec
Electroweak and grand unification symmetry(I.e. strong force) breaking
Give size of universe when transition occurred
2) Inflation
	amplitude and wavelength of grav. Waves may be related to density fluct.

Detecting a random background grav. Radiation requires detection of long wavelengths, e.g. a space based laser interferometer.

## Sources of Gravitational Waves

- Black holes orbiting each other generate gravitational waves.
- Merging black holes also generate gravitational waves.

**Notes:**
Video file is “blackhole2.qt.mov”, courtesy of Dr. Michelle Larson, Center for Gravitational Wave Physics, Pennsylvania State University.  Used by permission.

## Catching a Gravitational Wave

**Notes:**
This is Michelle Larson’s explanation:

The idea here is that, when a gravitational wave passes through, the distance between the two end points changes as measured by how long it takes light to traverse that distance, but the end points themselves do not "move". The coordinate location of the end points does not change, that is, they are still fixed four squares from the edge.  For example, the end station mirrors in LIGO stay fixed, it is the space between them that is stretched and squeezed by the gravitation wave, thus causing the light to take longer or shorter to travel the distance than when the wave isn't there.

The proof masses in LISA are the objects that we are measuring the light travel time between. [ie the proof masses take the place of the little people in the above fig.] Those masses are free floating, on spacetime geodesics. With no forces acting on them they will remain forever and for always on the same geodesic path. The spacecraft that surrounds each proof mass is there to buffer it from external forces such as solar wind and the like. The spacecraft has thrusters to help move it around such that the proof mass remains undisturbed in the center. The laser light will arrive from a neighboring spacecraft and the time stamp in the data will indicate when it hits the proof mass. If a gravitational wave passes by, the proper distance between two proof masses will change, and thus the light travel time will change, even though each individual mass never left a geodesic path.

Shane Larson developed this image.

## Laser Interferometer Space Antenna (LISA)

**Laser Interferometer Space Antenna (LISA)**

**LISA uses a laser based Michelson interferometer to monitor the separation between proof masses in separate spacecraft.**** **

**Joint ESA-NASA project**

**Three spacecraft separated by 5 million km.**
**Each spacecraft includes two freely falling test masses.**
**Distance **_**changes**_** measured with precision of  4 ppm RMS over 100 seconds.**

**Notes:**
LISA will detect low-freq grav. Waves (with periods 10-1000 s).  This is in range for compact binaries, merging super massive black holes, in spiral of white dwarfs, neutron stars and stellar-mass black holes into super massive Black holes
inspiraling maps the full geometry of gravity around supermassive black hole.
 mergers will aid in understanding galaxy evolution and test GR in its extreme limits.

May also detect violent events from early universe - phase transitions.

Micro-newton thrusters keep the spacecraft centered about the test masses

N.B. LISA measures just the arrival time of the laser light at the test masses.  The “interferometry” is done on the ground.  So LISA isn’t an active interferometer (like LIGO is) - ie the fundamental data isn’t fringe patterns, but the arrival times.

## What Happens at the Edge of a Black Hole?

**Close to a black hole event horizon, **
**extreme distortions of space & time predicted by Einstein can be observed**

**Black holes are ubiquitous in the Universe**

**Chandra Deep Image**

**What Happens at the Edge of a Black Hole?**

**Notes:**
Black holes are everywhere!

Just as the Hubble deep field shows galaxies, the Chandra Deep field shows black holes.

## What Happens at the Edge of a Black Hole?

**Japan-US ASCA satellite studied iron gas orbiting near the event horizon of a black hole.**
**Iron line emission exhibits a distortion due to motion of gas and strong gravitational effects near the black hole.**
**Line profile provides a probe of regions near black hole.**

**Notes:**
Video is Astro-E2’s “blackhole_spectrometer_small.mpg”

See Imagine News July 2002:Observations of NGC 3516 by Jane Turner & friends using Chandra and XMM. GR effect can be phrased as “the black hole's strong gravity tugs at light particles, stealing some of their energy.”  Observations like this also aid in study of accretion flow and magnetic field

## Measuring Black Holes via Spectroscopy

- Better determination of black hole parameters by studying individual blobs falling into event horizon.
- Measure effects of black hole spin on nearby space-time.
- Study intermediate size black holes.
- Growth of supermassive black holes early in the universe.

**Notes:**
Following the individual blobs also shows us structure of the disk.

Intermediate black holes: as missing link between stellar black holes and AGN.  How the AGN form. 

Growth of Supermassive B.H: cosmic feedback - how bh and galaxies evolve together. 

## Constellation-X

*A fleet of 4 X-ray Telescopes to perform high resolution spectroscopy on faint x-ray sources**** ***

**Each telescope 10 meter focal length.**
**4 telescopes increase the light collection area.**
**Launched on two Delta rockets.**
**Placed at L2 point (4x distance to moon)**
**4 - 10 year lifetime.**

**Notes:**
L2 is where WMAP is, and where JWST will be.

## Constellation-X: Achieving High Resolution Spectroscopy

- X-ray Microcalorimeter Spectrometer:
- Measure the heat from an x-ray to determine the x-ray’s energy.

- Resolution of 4 ev for a 6 kev x-ray energy. (25x-100x better than current sensitivity.)

**Notes:**
The Astro-E2 XRS is 6x6 (each pixel is 0.624mm), and 3.75 mm on a side
On Con-X, the XMS is 32x32 (each pixel is 0.25mm), and 8 mm on a side.

Animation is heat3.gif

## What is the Dark Energy?

**What is the Dark Energy?**

- Einstein introduced the Cosmological Constant to explain what was then thought to be a static Universe, “*my biggest mistake . . . ”*

- Empty space has energy.  It’s gravitational effect pushes the universe apart.
- Need a form of energy that is elastic:
-  Vacuum energy (= Cosmol. Const.)
-   But it’s effect may be too large
-  Quintessence (particle field)

- Astronomical Tools: Surveillance & Interrogation
-  Measure expansion via fluctuations in CMB.
-  Measure expansion via more SN and clusters of galaxies.

**Notes:**
Plot shows initial deceleration of the universe, then acceleration of the expansion about 10 billion years after BB (3 billion years before Sol System formed)

Need a form of energy that is elastic (neg. pressure)
  - Maybe the quantum vacuum (but it currently is way too big).  Einstein’s cosmological constant was identified w/ the zero-pt vacuum energy of quantum fields in later years after he rejected it)
  - Quintessence (a particle field) - topological defects from phase transitions could get tangled and exert a neg. pressure
Relation to Cosmological constant: Einstein’s _x0008_Lamda - empty space has energy and couples to gravity.

Astronomical tools: Measure rate at which structure forms
measure expansion rate of universe via temp variations in CMB - gives expansion history from 300,000 years to present
Measure distances to more supernovae - expansion history to z=2
Gravitiational lensing - measures rel. distance between src and lens

## Constellation-X and Dark Energy

- Dark Energy with Galaxy Clusters

- Compare Distance with redshift to measure history of expansion of the universe.
- Examine the growth of structure in the universe**.**

**Notes:**
Measure expansion vit clusters of galaxies
Simple message:
Clusters are ideal samples of the universe (“What goes on in Vegas, stays in Vegas.”) because they are “self-contained.”  
You can measure the fraction of mass that is baryonic (ie protons, neutrons).  This fraction is independent of distance.  Astronomers measure the temperature and surface brightness of the x-ray gas.  Using the fact that the gas fraction is constant for all clusters, they can derive the distance to the cluster.  They then compare that to the distance derived from its recession velocity.  This can extend the distance (and time) out to which we can measure the rate of expansion of the universe.
So with Sn Ia, the brightness and light curve decay are “standard” - here the composition is the “standard”

More complicated:
One measures the x-ray temperature and surface brightness.  From this one can get the gas mass if you know the distance.  But with the gas mass fixed, we can derive the distance.  
You adjust your cosmology (ie z’s relation to distance) to make the gas fraction constant.  From this you get cosmological parameters and a handle on dark energy.

## Realizing Science Beyond Einstein

_**Einstein Great Observatories**_ **providing breakthrough increases in capabilities to address all Beyond Einstein science:**
**LISA: Gravitational waves from merging black holes and the early Universe.**
**Constellation-X: Spectroscopy close to the event horizon of black holes and place constraints on dark side of the Universe.**
_**Einstein Probes**_ **to address focused science objectives:**
**Determine the amount and nature of the Dark Energy. **
**Search for the signature of inflation in the microwave background via gravitational waves. **
**Take a census of Black Holes of all sizes in the Universe.**
_**A technology program, theoretical studies and an education program**_** to inspire future generations of scientists and engineers towards the vision:**
**Directly detect the gravitational waves emitted during the ****Big Bang.**
**Image and resolve the event horizon of a Black Hole. **

*Three inter-linked components that work together:*

## Image a Black Hole!

- 0.1 arc sec resolution

- HST Image

- M87

**Hubble, Chandra, and other observatories ****are showing black holes are common place ****in the Universe.**
**Black holes provide a unique laboratory ****to test Einstein’s theory of gravity. **

**A future black hole imager with a resolution one million times Hubble will observe the effects Einstein predicted.**
**X-ray emission from close to the event horizon provides a powerful probe.**

## Observe the Big Bang

- Detect the gravitational waves from the earliest moments after the Big Bang.
- Provides a direct view of the formation of space and time.
- Big Bang Observer will also detect mergers of neutron stars and black holes, giving the rate of expansion of the universe through time.

## Beyond Einstein Timeline

**Beyond Einstein Timeline**

**Notes:**
LISA launch is 2015 with first results 2017-12018, 5-10 year mission
Con-X a few years after that.

So these are projects for future scientists!

## The Story of “Beyond Einstein”

- Science is an endless frontier
- Einstein changed our way of thinking about the universe, but we are going beyond that.
- Science is a search for answers
- Nature of science inquiry
- Science as a process and as a human endeavor.
- When we do not know the answers, we work on phrasing the questions.
- We push the envelope of what we know.
- We push the envelope of our technology.

## The 21st Century 

- How did the Universe begin?  Does time have beginning & an end?  Does space have edges?  The questions are as old as human curiosity.  But the answers have always seemed beyond the reach of science. . .
_*until now!*_

**The 21st Century **

## Dark Energy Probe 
Determine amount of dark energy, and whether it changes.
Ex. Search for large numbers of Type Ia supernovae.
Inflation Probe
Map polarization of Microwave Background to search for signature of gravitational waves from the Big Bang.
Black Hole Finder Probe
Take census of black holes in the universe
Ex. Use wide-field X-ray telescope

**Determine amount of dark energy, and whether it changes.**
**Ex. Search for large numbers of Type Ia supernovae.**
**Inflation Probe**
**Map polarization of Microwave Background to search for signature of gravitational waves from the Big Bang.**
**Black Hole Finder Probe**
**Take census of black holes in the universe**
**Ex. Use wide-field X-ray telescope**

**Einstein Probes**

- Three focused missions, each designed to address a single high priority science question:** **