Ripples In Spacetime by Govert Schilling, 2017,
The Belknap Press of Harvard University Press, Cambridge
Notes by Dennis Hands November 2018
How Science Works (page 41)
Observations are explained by theory. Theory makes predictions. Experiments check on predictions. If they are confirmed, confidence in the theory grows. If not, something is amiss. Tweak your theory or come up with a new one.
Then, start doing experiments again.
How Interferometry works
Signal recycling: using “squeezed light” an quantum optics trick in which the Heisenberg uncertainty principle is tweaked in our favor, WTF?
1783 First idea of a black hole “dark stars” (213)
1845 Chrisophorus Buys Ballot hires train and musicians to hear Doppler effect. Is this a correction of my Doppler story with the train too loud???
1887 Speed of Light Problem (33)
1925 Cecelia Payne found that stars are mostly hydrogen(78)
1934 Prediction of neutron stars by Fritz Zwicky and Walter Baade
1960’s Virginia Tremble, Weber’s widow, had relationship with Kip Thorne (135)
1964 Term “black hole” first used by journalist Ann Ewing
1967 Jocelyn Bell discovers pulsars
1972 Joe Weber marries Virginia Tremble (73)
1973 Kip Thorne, Misner and Wheeler wrote Gravitation, a “bible of general relativity”
1974 Joe Weber claims to have detected gravitational waves (60)
1989 Kip Thorne estimates that iLIGO might catch one or maybe to neutron star mergers during the planned decade of service
2000 Death of Virginia Tremble’s husband (75)
2015 September 14: GW150914 LIGO first detects gravitational wave.
2015, September 18: “engineering mode” is the official start of LIGO’s Observing Run 1.
2015 October 12: another gravitational wave candidate detected,
2015 December 26: a third candidate only 99% chance, so “Trigger”
In less than a billion years, the Sun’s luminosity will have increased enough to boil away Earth’s oceans
10,000 or 20,000 years later, Planetary nebula
Helium fusion is hotter, so the Sun will expand to become a bloated red supergiant
History of the Universe (12)
- 14 volume encyclopedia set, each volume a thousand pages of fine print
- Big Bang on the first line of the first age of Vol. 1.
- First stars galaxies halfway thru Vol. 1
- Birth of our Sun and Planets in Vol. 10
- Dinosaurs go extinct on p 935 in Vol. 14
- Homo sapiens appear on the bottom fifth of page 1,000
- All of our written history in second half of last line
Elementary Particles (13): the up quark, the down quark, and the electron
Just as letters can be grouped into words, these can be grouped to make atoms, molecules, compounds, (13) Gravity v, Electromagnetic force
Tear a small piece of paper into shreds and let them drop onto the desk: Gravity! Now take a small plastic comb and rub it on hair or on a woolen sweater (or a balloon rubbed on my hair) and hold it a few cm above the snippets A balloon rubbed can be stronger than the gravity from a whole planet (25-6)
“Matter tells spacetime how to curve; spacetime tells matter how to move.” John Archibald Wheeler (23)
Our Sun is about 199 times the diameter of the Earth, 1,5 million Earth volumes
Why spherical? Try putting two handfuls of snowflakes as close to each other as possible = Snowball! There’s no way to pack matter more efficiently than as a sphere. (83)
Hulse-Taylor binary pulsar orbital period of 7.75 hours, would have a gravitational wave frequency of 72 microhertz, wavelength of 4.2 billion kilometers
Corpses of stars
Life of a neutron star
- very massive star with processes speeded up
- Hydrogen fusion, expanding layers, helium ignition, formation of carbon and oxygen core, loss of outer hydrogen mantle
- With greater mass, carbon fusion to neon and others for a thousand years
- Neon converts to magnesium for a few years
- Oxygen fusion to silicon takes over for a year or so
- For less than a day, silicon fuse into several elements including iropn and nickel
- Core of iron does not fuse into a heavier element
- Within a second or less, star collapses in on itself. Neutrons
What we perceive as gravity is really the effects of curved spacetime on the motion of other bodies. Closer to BH, clocks will tick slower (15)
When two black holes spiral and merge into one, it rings down like a struck gong. (209)a
When a scientist is talking bout the mass of a black hole, that’s really a description of the amount of spacetime curvature (218)
With binary black holes we would see shorter orbital period.
Redshift does not provide us with original distance. With the effect of expanding space redshift tells us how long the galaxy’s light has been traveling thru space. “The galaxy is so remote that its light, traveling through the expanding space, too 7 billion years to reach us.”
Gets reduced to “The galaxy is 7 billion light years away.” (157)
Two types: short burst (fraction of a second) possibly from neutron star mergers
Long burst (up to a couple minutes) powerful supernovae (256)
Good explanation (17-20) check this
The universe does not have a single expansion velocity, Expansion velocity depends on the distance between two objects.
Between two relatively close points, its 10,000 km per second. Between two distant objects it might be 50,000 km per second. (159)
Big misconception that at the time of the Big Band, the universe was a single point. If universe if infinite now (Schilling assumes that for the rest of the book) is was a fraction of infinite which is still infinity (160)
Another way to look at it was 13.8 billion years ago temperature and densities were extremely high everywhere. (160-1)
Tiny amount of polarization imprinted on CMB 13.8 billion years ago It’s the “fingerprint” of the uneven distribution of matter in the early universe. (175)
“Inflation is the common denominator for a bunch of hypothetical scenarios, one of which might be true.” (175)
“Gravitational waves propagate at the speed of thought.” Arthur Stanley Eddington (circa 1918)
Schilling calls gravitational waves “Einstein waves” every now and then (65)
Here are some Models of Einstein Waves:
One dimension: a taut jump rope: stretch and compress in different places so total length doesn’t change (65)
Two dimensional: sheet of graph paper: The squares on the paper would stretch and compress so size of paper doesn’t change, by stretching and compression (65)
Three dimensional: Imagine 3-D graph paper with cubes grow longer and shorter perpendicular to the direction of the wave as the wave passes thru (66).
Similar to density ripples propagating thru Jello when tapped. (66)
Better analogy: a cement block hit with a sledgehammer: much stiffer than Jello (67)
Frequency of gravitational waves (66) wavelength of 1,500 km because gravitational waves travel at te speed of light
Amplitude of a gravitational wave is a measure of its strength. Amplitude decreases with distance, inversely proportional and is unbelievably small. NOT the inverse square law (66)
What we learn from gravitational waves: (210)
- orbital period from the observed wave frequency
- masses and densities from the same wave frequency
- mass from the duration of the event
- diameters from orbital frequencies
- mass of final black hole from wave frequency during the ring-down phase. (210)
“The only way a black hole merger can communicate with the rest of the universe is through gravitational waves.” (255)
In nature small things always outnumber the large things. (more mice than elephants)
Science can’t explain creation? Science doesn’t know how to cure cancer. That’s no reason to end scientific endeavors.
Apparently, according to Schiller, Yogi Berra was quoting Niels Bohr who said Prediction is difficult, especially if it’s about the future. (295)
Today’s astronomy s like a deaf person on the jungle. Sees stuff. Then imagine hearing returns sounds provide more info about the stuff she sees, but also gives us clues about stuff not seen! (298)
Virginia Trimble (76-77) I first met Dr. Trimble in the year 2000.
IceCube Laboratory in Antarctica is described on pages 269-70. In 2011 I met Dr. Francis Hazelton of IceCube.
John Mather and COBE are mentioned on page 172 I met and interviewed Dr.
Mather in 2016.
Gabriella Gonzales, LIGO spokesperson, autographed page 190 of my copy of this book. I met Dr. Gonzales in 2018.
Jocelyn Bell and her pulsars are included on p. 229. Jocelyn Bell-Burnell came to visit Cline Observatory in 2014.
I listened to a bit of each track on “Unknown Pleasures” by the band Joy Division, and can say it’s not for me.