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- February 24, 2014, Sonoma State University lecture, Charles Lawrence, Jet Propulsion Laboratory, “The universe according to Planck”.
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-. Planck is a telescope that sees the Cosmic Microwave Background light that has traveled 13,800,000,000 lightyears to reach us. We see the picture of the Universe 380,000 years after the Big Bang.
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-. The Planck Telescope is orbiting the Sun along with the Earth at an altitude of 930,000 miles. This spot is called L2, Lagrangian Point 2. It is a point in space where the gravity of the Sun and the gravity of the Earth just cancel.
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-. Launched in May, 2009 it started to survey the sky in February, 2010. After 3 1/2 years of data collection it was decommissioned October, 2013.
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-. The telescope rotated one revolution per minute and scanned a beam 5 arc minutes wide across the entire sky, 360 degrees. After six months of scanning it had captured the radiation of the entire sphere of the sky over the frequency range from 30 to 857 gigahertz. Actually, 9 specific frequencies over that range.
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-. The cosmic microwave background radiation covers a range from 60 to 600 gigahertz, this corresponds to wavelengths from 0.5 to 0.05 centimeter wavelengths. The peak amplitude of the signal is at 270 gigahertz ,or, ¼ electron volts.
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-. 13.8 billion years ago the Big Bang occurred. The Universe was a sea of hot plasma, charged particles, no light could escape this expanding ball of plasma, until 370,000 years later it had cooled down from the 100,000,000 degrees Kelvin to 3,000 degrees Kelvin.
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- 3,000 degrees Kelvin is a low enough temperature for protons to start capturing electrons and become neutral atoms. When this happened photons of light were no longer being bounced between charged particles and could escape into outer space. That light is the Cosmic Microwave Background radiation, CMB , that we see today.
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-. The CMB was measured at the Lagrangian 2, point in space because at 930,000 miles altitude it was a point where the Sun and the Earth's gravity canceled. This meant that a very low amount of energy was needed to hold the telescope in place. Secondly, L2 was in Earth's shadow blocking most of the Sun's radiation.
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- The bolometric detectors used to measure this CMB radiation only work at the lowest possible temperatures, near absolute zero, -273 degrees C. Even then all the noise in temperature variations caused by the Sun, by the galaxies , by dust, by the instruments themselves,,,………. had to be subtracted from the data in order to see the cosmic microwave background radiation.
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- The Lagrangian points in space were first calculated by Joseph- Louis Lagrange, ( 1736 to 1813), the youngest of 11 children born in the a Italian Kingdom of Piedmont. He read an essay by Halley and got infatuated with a calculus that studied paths of the comets. He became a geometry teacher. His math skills eventually led him to become the head of the Berlin Academy. His book, ‘Analytical Mechanics“, was published in 1788. Newton's laws for gravity worked for 2 bodies. But what was the math needed to deal with 3 bodies i.e. the Sun, the Earth, the Moon, or Jupiter? His calculations came up with the 5 Lagrangian points that satellites use today. He worked with Laplace in 1795 to devise the Metric System of units we used today.
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-. Lagrange’s math identified 5 points where the gravitational forces of the Sun and the Earth came into balance. Like currents in the ocean that cross, cancel each other out, and collective floating trash, the Lagrange point 1 is in between the Earth and the Sun where their gravity's cancel. This is a good place to park a spacecraft because they can hold stable orbits with minimal outside forces, (rocket boosters). The Solar Heliocentric Observatory spacecraft is parked there now, SOHO.
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- Lagrange point 2 puts the Earth in the middle with L2 on the outside of a straight line connecting the Earth and the Sun. The Wilkinson Microwave Anisotropy Probe, WMAP, is parked there. So is the Planck telescope.
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-. Max Carl Ernst Ludwig Planck, 1858 to 1947, studied in Munich with Hertz and Kirchhoff. In 1880 Planck joined the faculty. His research worked on the Blackbody Problem. Why does a Blackbody absorb low frequencies but not high-frequency radiation? His math gave a solution by quantifying absorption in “quanta” instead of in continuous wave of energy. The size of the quanta was proportional to the frequency of the radiation. Violet light contains twice the energy as red light. He solved the problem by showing that higher frequencies radiation requires more energy. The small constant in the equation for the ratio of frequency to energy quanta became known as Planck's Constant of Action, E = h*f.
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-------------------- h = 6.6*10^-34 (kilogram*meter^2) / seconds
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- In 1905 Einstein used this concept to describe the Photoelectric Effect. In 1913 Bohr used it in the quantum theory of the atom. Today the math is known as Quantum Mechanics. In 1918 Planck received the Nobel Prize in Physics.
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- The Planck telescope parked at L2 was cooled to -273.05 C, it was the coolest object in space at the time. It had 48 bol0metric detectors which measured power of incident electromagnetic radiation by heating material which changes its electrical resistance as a function of temperature.
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-. The CMB temperatures it has to measure are extremely small variations, between 2.735001 and 2.734999 degrees Kelvin. Visible light has energies ranging from 1/2 to 1 electron volt. This CMB radiation being measured is on the order of 0.00003 electron volts.
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-. The CMB had a lot more energy 13,800,000,000 years ago, but, over that 13.8 billion years the Universe has expanded to 45 billion light-years radius. When wavelengths are stretched energy is lost, E = h*f and E = h*c/w. The wavelengths have stretched out from 0.1 nanometers to 10,000,000 nanometers. The temperature is equal to 0.0029 / wavelength. The temperature has decreased from 3,000 degrees Kelvin to 2.73 degrees Kelvin.
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-. The hot to cold variations, the spots, on the Cosmic Microwave Bare are the size of large galaxies today. They started out as quantum fluctuations present in the Big Bang plasma and have stretched out to 100,000 lightyears.
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- The data in a full sphere of the sky contained 50,000,000 pixels. After the noise was removed the CMB represented the output of the universe expansion from 10^-35 seconds to 13,800,000,000 years.
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-. The amazing thing in science today is that this data can be simulating in a computer with only 6 variables. The variables, or parameters, are played with until the entire Universe expansion scenario matches what we observe today after the13.8 billion years of expansion.
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-. Planck’s contribution was making these measurements with higher resolution and with greater precision.
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--------------------------------. In 1989 the COBE telescope had 7 arc degree resolution
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-.------------------------------ In 2001 the WMAP telescope had 15 arc minutes of resolution. That's 45 % of an arc degree, the full moon is 50% of an arc degree.
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-.------------------------------ In 2009 the Planck telescope had 5 arc minutes of resolution which is 8% of a degree.
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-. The 6 parameters simulated from this higher precision data were:
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------------------. One age of the universe = 18,817,000,000 + or - 48,000,000 years
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------------------. The Hubble Constant = 67.4 kilometers per second per megaparsec
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-.-------------------- Baryon density = 0.022068
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---------------------. Cold Dark Matter density = 0.12029
-.------------------- Dark Energy density = 0.6825
-------------Time of reorganization = 377,730 + or - 3,200 years. A Redshift of 1090.
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--------------------- The results say that ordinary matter is only 4.9 % of universe.
-.------------------- Dark matter is 26.8 % of the universe
--------------------. Dark energy is 68.3 % of the universe.
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- In other words the part we don't yet understand, the part that is “dark” is 95.1 % of universe.
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-. What a great success the Planck telescope mission has been in understanding where we came from. The data will continue to be studied for years. Removing more noise, bringing more precision. There is much still to learn and as Richard Feynman was fond of saying, “the greatest danger in science is fooling yourself“. An announcement will be made shortly ,stay tuned.
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-. See review #1108, “What Forces Control Everything
-. Review #823, “ Sound Waves in the CMB
-. Review #757, CMB
-. Review #1586, “Measuring the CMB
-. Review #1305, “Cosmic Harmonics”
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