Power in the Universe: The lecture explores the most powerful objects in the universe, often driven by gravity and magnetism.
The Sun
Solar Eruptions: Solar prominences and flares, with the sun being relatively inactive compared to other stars.
Differential Rotation: Sun rotates at different speeds at the equator (26 days) and poles (30 days), causing magnetic field lines to spring out like rubber bands.
Historical Observation: Brightest solar flare recorded by Carrington in 1859, leading to auroras and telegraph disruptions.
Potential Impacts: Modern solar flares could disrupt transmission systems and satellites, including GPS.
Solar Flares
Energy and Frequency: Flares can range in energy and are plotted logarithmically to understand their occurrence rate and potential energy.
Kepler Satellite Observations: Continuation of solar flare patterns seen in thousands of stars similar to the sun.
Power Limits in the Universe
Maximum Power Equation: Maximum power derived from an object's mass using Einstein's E=mc^2 and light crossing time, resulting in a theoretical limit of 3.6 x 10^52 watts.
Eddington Limit: Limit to power due to radiation pressure opposing gravitational pull, demonstrated by comet tails.
Stars and their Fate
Life Cycle: Evolution of stars from hydrogen burning to potential endpoints as white dwarfs, neutron stars, or black holes.
Supernovae: Different types of supernovae (core collapse, binary mergers) and their contributions to heavy elements like iron and oxygen in the universe.
Neutron Stars and Pulsars
Crab Nebula: Remnant of a supernova in 1054 AD, containing a pulsar with highly magnetized spinning characteristics.
Magnetars: Neutron stars with extremely high magnetic fields, leading to intense flashes and ionization of Earth's atmosphere.
Black Holes
Observation: Evidence of black holes through the motion of stars and gravitational influences, including the supermassive black hole at the center of our galaxy.
Event Horizon: Concept of event horizon where gravity is so strong that not even light can escape, warping space-time.
Theoretical Predictions: Early theoretical predictions by John Mitchell and later advancements by Einstein and Schwarzschild.
Quasars: Extremely luminous objects powered by accretion of matter into black holes, visible even from great distances.
Gravitational Waves
Observations: Merging black holes observed through gravitational waves by instruments like LIGO, demonstrating extreme power outputs.
Implications of Mergers: Gravitational waves from mergers can be more powerful than the combined luminosity of all stars in the universe.
Feedback and Galaxy Evolution
AGN and Quasars: Influence of active galactic nuclei in shaping galaxies through radiation pressure and gas outflows.
Galaxy Structure: Correlation between black hole mass and galaxy mass, affecting star formation and evolution of galaxies.
Summary
Black holes and their associated phenomena demonstrate the most extreme manifestations of power in the universe, influencing the formation of elements, galaxy structures, and potentially playing a role in high-energy astrophysical events.