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Dark Matter | SciByte 3

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This week on SciByte …
We take a look dark matter and dark energy, why even though we can’t see them directly some scientists still believe they exist, where the theories for them came from, what they are, and how they affect the universe.

We’ll also take a look at a few satellites and studies looking for either direct or in-direct evidence of these mysterious phenomenon.

All that and more, on SciBye!

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Show Notes:

Fritz Zwicky  

  • Found a total of 120 supernovae, over a stretch of 52 years.  Involved in using Tpe 1A supernovae as ‘standard’ candles.  In 1937 posited that galaxy clusters could act as gravitational lenses like previously discovered Einstein effect, confirmed in 1979.
  • The first person to provide evidence and infer the presence of dark matter
  • Virial Theorem – for a stable, self-gravitating, spherical distribution of equal mass objects (stars, galaxies, etc), the total kinetic energy of the objects is equal to minus 1/2 times the total gravitational potential energy. In other words, the potential energy must equal the kinetic energy, within a factor of two.

Dark Matter

  • most stars in spiral galaxies orbit at roughly the same speed which suggest that either Newtonian gravity does not apply universally or that, conservatively, upwards of 50% of the mass of galaxies was contained in the relatively dark galactic halo [stars and globular clusters surrounding the galaxy]
  • Astrophysicists predicted the mass would be low in density, but high in temperature (~million degrees Celsius)
  • Theory states there should be about double the amount of matter in the local Universe compared to what is observed
  • the majority of this missing mass should be located in large-scale cosmic structures called filaments – a bit like thick shoelaces
  • Through A Universe Darkly” – A Cosmic Tale of Ancient Ethers, Dark Matter, and the Fate of the Universe

Dark Energy

  • Edwin Hubble first noticed that the Universe was actually expanding, in 1932.
  • Believed to be behind the acceleration of the expansion of the Universe
  • Visual representation of the expansion of the Universe
  • Is Einstein’s vision of gravity, general relativity, incorrect on large cosmological scales?
  • Does “empty space” possess its own energy?

Measuring the Expansion of the Universe [ Hubble constant, or H0 ]

  • Named after Edwin Hubble who first measured the expansion of the universe nearly a century ago
  • Einsteins ‘biggest blunder’ not actually a blunder
  • Type Ia supernovae : produces consistent peak luminosity because of the uniform mass of white dwarfs that explode via the accretion mechanism
  • Cepheid variable stars are the backbone of the distance ladder because their pulsation periods, which are easily observed, correlate directly with their luminosities
  • Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), two of the nearby satellite galaxies of our own Milky Way Galaxy, since they contain large number of Cepheids, they can be used to calibrate the distance scale
  • Redshift / Blueshift : How fast are things moving away from us? [Red=away]

Cosmic Microwave Background (CMB)

  • Cosmic Background Radiation Image
  • The radiant heat left over from the Big Bang. (first observed in 1965)
  • properties of the radiation contain a wealth of information about physical conditions in the early universe and a great deal of effort has gone into measuring those properties since its discovery.
  • The hot spots and cold spots, which differ in temperature by only millionths of a degree, can be interpreted as very slight differences in the crowding together of matter in the young universe. Hot spots had slightly more matter than average; cold spots a bit less

Wilkinson Microwave Anisotropy Probe

  • 3D model [proposed to NASA in 1995, launched in 2001]
  • cooled microwave radiometers measure the properties of the cosmic microwave background radiation over the full sky
  • Measuring the temperature of the microwave sky to an accuracy of one millionth of a degree revealing conditions as they existed in the early universe
  • using differences in temperature measured from opposite directions (anisotropy).
  • Orbits at Lagrange point 2 :provides for a very stable thermal environment and near 100% observing efficiency since the Sun, Earth, and Moon are always behind the instrument’s field of view

Anisotropy

  • property of being directionally dependent
  • defined as a difference, when measured along different axes, in a material’s physical or mechanical properties [light coming through a polarizer]

Wilkinson Microwave Anisotropy Probe results

  • Complete census of the universe finds that dark matter (not made up of atoms) make up 23.3% (to within 1.3%)
  • Accuracy and precision determined that dark energy makes up 72.1% of the universe (to within 1.5%), causing the expansion rate of the universe to speed up.
  • making accurate measurements of the cosmic microwave background fluctuations, WMAP is able to measure the basic parameters of the Big Bang model including the density and composition of the universe
  • Microwave light seen by WMAP from when the universe was only 380,000 years old, shows that, at the time, neutrinos made up 10% of the universe, atoms 12%, dark matter 63%, photons 15%, and dark energy was negligible. In contrast, estimates from WMAP data show the current universe consists of 4.6% percent atoms, 23% dark matter, 72% dark energy and less than 1 percent neutrinos.
  • Mapped the Cosmic Microwave Background (CMB) radiation (the oldest light in the universe)
  • WMAP definitively determined the age of the universe to be 13.73 billion years old to within 1% (0.12 billion years)
  • Reported the first direct detection of pre-stellar helium, providing an important test of the big bang prediction. [Jan26, 2010]
  • Nailed down the curvature of space to within 1% of “flat” Euclidean
  • Started to sort through the possibilities of what transpired in the first trillionth of a trillionth of a second, ruling out well-known textbook models for the first time

Australian Student Uncovers the Universe’s Missing Mass

  • Conducted a targeted X-ray search for the hidden matter and within just three months made a very exciting discovery
  • Dark Matter theories have been based solely on numerical models

WiggleZ Dark Energy Survey

  • Einstein Confirmed Again: Dark Energy Present In The Universe
  • Firstly, observed how dark energy opposes gravity by speeding up the overall rate of expansion of the Universe
  • Secondly, observed how dark energy opposes gravity by slowing down the growth of clusters and superclusters with time
  • mapped the distribution of galaxies over an unprecedented volume of the Universe
  • WiggleZ scientists have made a 3-D map of more than 150,000 galaxies near and far to trace the universe’s evolution over time
  • 10min Podcast on WiggleZ

Additional Information:


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Time | SciByte 2

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We spend some time looking at time, how we have measured it’s passage throughout history, philosophically, how it’s affected by gravity, and the very concept of time itself.

Plus find out why Einstein proposes that we travel through time at the speed of light, how Atomic clocks work, and is it possible gravitational fields warp time?

All that and more, on SciBye!

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Show Notes:

Concept:
  • “Time is what keeps everything from happening at once.” – Ray Cummings, Sci-Fi Author

Measurement:

  • Smallest units of time = Planck time [time it takes for light to travel the shortest distance current theories can handle]
Philosophy:
  • Why do we always move forward?
Scientific:
  • Is time eternal, or a side effect of “space”?

Philosophy on the Nature of Time:

  • Immanuel Kant believes time is all in our heads, as a necessity to quantify sensory inputs of everyday existence. Also believes in predestination, and that Free Will can only exist outside of Time.
  • Martin Heidegger believes similarly, and that humans should be capable of “stepping out of time” by a specific form of non-associative thinking. The past, present and future can become one within our minds, and experienced in random order. (uhm, excuse me?!?)
  • Henri Bergson believed that Time could not be measured because it is infinite and malleable, and shapes itself to the perceptions of an individual.
  • “Time is an illusion” is a common saying in Buddhist teachings.
  • HG Wells: “There is no difference between time and any of the three dimensions of space except that our consciousness moves along it.” — The Time Machine
  • C. S. Lewis “The future is something which everyone reaches at the rate of 60 minutes an hour, whatever he does, whoever he is.” (but do those min pass by at the same rate)

‘When’ was the Start of the Universe, T=0 point

    • Red Shift / Blue ShiftDoppler Effect light waves act similar to sound waves coming towards you or away from you.  Blue shift = Away; Red shift = Near
    • Type 1A Supernova – PIC - To judge distance and speed [red shift/blue shift]
    • Roughly 13.7 Billion Years ago

Measurement ‘devices’ through history

    • Mayan’s : Mayan Calender created during the Dark Ages in Europe

Calculated

  • Earth orbit @ 365 days [Actual = 365.2422 days, 0.06%]
  • Lunar Month @ 29.53086 days [Actual = 29.53059 days; 0.0009%]
  • Mercury orbit @ 117 days [Actual = 116 days; 0.86%]
  • Venus orbit @ 584 days [Actual = 583.92 days; 0.01%]
  • Mars orbit @ 780 days [actual = 779.936 days; 0.008%]
  • Antikythera mechanism - is an ancient mechanical computer designed to calculate astronomical positions. It was recovered in 1900–1901 from the Antikythera wreck. Its significance and complexity were not understood until decades later. Its time of construction is now estimated between 150 and 100 BC. The degree of mechanical sophistication is comparable to a 19th century Swiss clock. Technological artifacts of similar complexity and workmanship did not reappear until the 14th century, when mechanical astronomical clocks were built in Europe

A day – 24 hours?

  • 2 Radio telescope set  on different points of Earth measure a radio wave from a quasar. They line up once a ‘day’ which is not always 24 hours [changes are in mili seconds]

Atomic Clocks

    • In certain elements [like Cesium] the Electrons will ‘jump’ between orbits and emit a flash of light at precise intervals [Cesium, 9 billion times a sec]  Video
    • Such a clock, if sent on a space shuttle, ticks at a different speed. Because it is further from Earth’s gravitational pull.

EINSTEIN:

    • Einstein proposes that we travel through Time at the speed of light.
    • Einstein: Spacetime is a single entity, not separate things. And because of the mixing of space & time, time ticks differently for separate entities, based on relative speeds.
    • The faster you travel through space, the slower you travel through time.
    • Proven by the Shapiro effect (blip in Mercury’s orbit, measured on opposite sides of the Sun)

Shapiro Effect

  • Gravitational fields warp time
  • blip in Mercury’s orbit, measured on opposite sides of the Sun – VIDEO

If time is flexible based on observation, then all of it always exists…

    • (Incorrect for quantum mechanics)
    • New theories suggest that “spacetime” is granular, and not fixed. On a large scale it looks like a single thing, but it actually flows as it is being created, in the future.

Black holes actually STOP time at their event horizon, to an outside observer.
But an observer falling in would see time speed up around them, the closer they got.

Time Travel?
High speed camera moments
Lighter

Busting Water Baloon

Additional Information
CPT – Charge, Parity, and Time Reversal (CPT) Symmetry

WIKI – Shapiro Delay

What Time Is It? (part 1 // part 2 // part 3 // part 4)


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Gravity | SciByte 1

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This week on SciByte …
We look at the results from Gravity Probe B and how they relate to Einstein’s predictions on mass, space, time and how they all interact with one another. We’ll also open up the guts of that crazy contraption, and discuss some of the impressive tech that made the whole experiment possible to begin with.

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Show Notes:

Gravity?

-Sir Issac Newton [Mathematician]
-1687 – His predictions predicted the existence of Neptune based on the motions of Uranus
-Mercury’s Orbit hower can NOT be explained by Newtonian math alone, but was resolved with Einsteins general theory of relativity in 1915
-Newtonian Calculations however still are accurate enough for most applications
-General Relativity – Albert Einstein [1907-1915] The observed gravitational attraction between masses results from their warping of space and time.
→ Space-Time is not flat, but can be stretched and warped by matter
-What this means, boiled down: Time moves slower under gravity

Gyroscope

-A device for measuring or maintaining orientation, based on the principles of conservation of angular momentum.
-Video : Gyroscope
-Video : Conservation of Angular Momentum : Spinning Skater

Gravity Probe A

-“A” confirmed the prediction that gravity slows the flow of time, and the observed effects matched the predicted effects to an accuracy of about 70 parts per million. [1976, and lasted <2hours]
-Used a hydrogen maser, a highly accurate frequency standard, to measure the rate change of a clock in lower gravity with high precision.

Gravity Probe B

-A star, a telescope, a spinning sphere [conceived in 1959, launched in 2004, decommissioned in Dec 2010]  [A Star, telescope, and space time]
-Gravity Probe B Cutaway
-Reference telescope sighted on IM Pegasi, a binary star in the constellation Pegasus
-Drag Free System
-Solar Radiation Pressure – Particles streaming away from Sun transferring momentum
-Atmospheric Drag [@624KM]
-Compensation done with helium boosters, full 6-degree motion (first ever)
-London moment gyroscopes
-A spinning superconductor generates a magnetic field whose axis lines up exactly with the spin axis of the gyroscopic rotor.
-Are housed in a dewar of superfluid helium @ a temperature of under 2 kelvins (−271 °C, −456 °F)
-A magnetometer determines the orientation of the generated field, which is interpolated to determine the axis of rotation.

** The pointer shifted by just 6,000 milliarcseconds — the width of a human hair as seen from 10 miles away
* At the time, the gyroscopes were the most nearly spherical objects ever made.

~ size of ping pong balls, they are perfectly round to within forty atoms
- Scaled to the size of the Earth, the elevation of the entire surface would vary by no more than 12 feet
* Measured changes in gyroscope the equivalent to an angular separation the width of a human hair viewed from 32 kilometers (20 miles) away over a one-year period. [0.5 milliarcseconds (1.4×10−7 degrees)]

Already Proven?

The Apollo astronauts left retro-reflector mirrors on the Moon, and laser ranging from Earth can now track their positions to millimeters. At that level of precision, the Moon’s motion in orbit has confirmed gravitomagnetism, the source of frame-dragging, to 0.15%, or 130 times better than GP-B.

Precision measurements of the Shapiro effect or gravitational time delay for light, most recently in 2002 by the Cassini space probe

Gravity – no uniform model for all scales

The laws of classical Newtonian physics remain accurate in predicting the behavior of the vast majority of large objects—of the order of the size of large molecules and bigger—at velocities much smaller than the velocity of light

Quantum mechanics

-By Newtonian Standards Atoms can’t exist
-Newtonian physics says that electrons would fall out of orbit into the nuclues
-Electron Orbits in actuality can only exist as very specific points
-Heisenburg Uncertainty principle – can’t know location AND speed

Black holes

-First conceptualized in 1783 by Henry Cavendish
-Infinite Density; Event Horizon [point of no return]

Dark Matter

-Matter that is inferred to exist from gravitational effects on visible matter and background radiation, but is undetectable by emitted or scattered electromagnetic radiation

Dark Energy

-Hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe
-Dark Matter/Dark Energy Estimates
-Some estimates state The Universe is made up of 23% Dark Matter; 72% Dark Energy; and Atoms a mere 4.6%

Additional Information :

SPACETIME: From the Greeks to Gravity Probe B
NASA : Gravity Probe B
Sky&Telescope : Gravity Probe B: Relatively Important?
PC Magazine : It Took More Than 50 Years, But NASA Proves That Einstein Was CorrectScientific American : Earth’s Mass and Motion Warps Spacetime as Einstein Said
engadget : NASA concludes Gravity Probe B space-time experiment
National Geographic : Einstein Theories Confirmed by NASA Gravity Probe
NASA Gravity Probe Confirms Two Einstein Theories
Wired : Floating Gyroscopes Vindicate Einstein
spaceRef : NASA’s Gravity Probe B Confirms Two Einstein Space-Time Theories
PCWorld:Experiment Confirms Space-Time Vortex Around Earth, Makes Our Heads Hurt
What’s 96 Percent of the Universe Made Of? Astronomers Don’t Know
YouTube | Lecture 1 | Modern Physics: Quantum Mechanics (Stanford)

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