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"Probing the Dark Universe" - A Lecture by Dr. Josh Frieman

Fermilab・87 minutes read

Fery Lab introduces upcoming events and lectures in physics, astronomy, and dark matter, focusing on expanding knowledge through various presentations and exhibits. The exploration of dark energy and matter, the composition of the universe, and ongoing surveys provide insights into the fundamental mysteries of physics and the evolution of the cosmos.

Insights

  • Fery Lab, introduced by Andre Sals, hosts diverse events like concerts, lectures, and exhibits, showcasing a range of topics from climate change to gravitational waves.
  • Dark matter, a major component of the universe, holds galaxies together, with research indicating its likely composition as weakly interacting massive particles (WIMPs).
  • The universe's accelerated expansion, driven by dark energy, challenges traditional gravitational theories, with dark energy constituting 70% of the universe's composition, driving crucial research through projects like the Dark Energy Survey.

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Recent questions

  • What events are scheduled at Fery Lab?

    Fery Lab, introduced by Andre Sals, hosts various events like a concert featuring flutists Jennifer Gunn and Tim Monroe, a lecture on climate change by Dr. Phil Mo, a performance by Stars of Dance Chicago, and a new lecture on gravitational waves by Barry Beish. Additionally, there is an exhibit called "Art of Darkness" from the Dark Energy survey displayed in the art gallery. Public tours of the particle physics laboratory are offered on Wednesdays at 10:30 a.m., and discussions by experts like Dr. Josh Freeman on the Dark Universe are also part of the schedule.

  • What is dark matter and its role in galaxies?

    Dark matter is a mysterious form of mass that does not emit light or energy but exerts gravitational forces, holding stars in their orbits within galaxies. Research by Ruben and collaborators found that stars' rotation speed around galaxies increases and flattens out at a higher value due to the presence of dark matter. Galaxies are primarily composed of dark matter, with evidence found through gravitational lensing in individual galaxies. Techniques like galaxy-galaxy lensing have been used to study the typical mass of galaxies, revealing dark matter halos around luminous galaxies.

  • How is dark energy related to the universe's expansion?

    Dark energy, constituting 70% of the universe's composition, plays a crucial role in the universe's expansion. Initially expected to slow down due to gravity, the expansion was discovered to be accelerating, challenging previous beliefs. This acceleration, attributed to dark energy or a different behavior of gravity on cosmic scales, poses a mystery in physics. The composition of the universe, with dark energy, dark matter, and ordinary matter, changes over time as the universe expands, impacting the formation of structures by gravity. Understanding dark energy is essential for predicting the future evolution of the universe.

  • What is the significance of the Dark Energy Survey?

    The Dark Energy Survey, initiated in 2013 and supported by the US Department of Energy and the National Science Foundation, aims to map the universe to study its expansion and clumpiness, providing insights into dark energy. Techniques like galaxy clusters, gravitational lensing, galaxy distribution, and supernovae observations are utilized in the survey. An international collaboration of 400 scientists uses the Blanco telescope in Chile, equipped with a high-resolution camera to capture images of galaxies for analysis. The survey's findings help in understanding dark energy and the universe's evolution.

  • How does dark matter impact the structure of the universe?

    Dark matter, a significant component of the universe's composition, influences the formation of large-scale structures like the cosmic web. It interacts through gravity, causing galaxies to form and cluster together. Techniques like weak gravitational lensing are used to study the distribution of dark matter and its impact on the universe's evolution. Recent discoveries of nearby dwarf galaxies rich in dark matter and the mapping of dark matter halos around luminous galaxies provide valuable insights into the role of dark matter in shaping the structure of the universe.

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Summary

00:00

Arts and Science Events at Fery Lab

  • Fery Lab is introduced by Andre Sals, part of the Arts and Lecture Series committee, responsible for selecting performers and speakers.
  • Upcoming events include a concert on Sunday featuring flutists Jennifer Gunn and Tim Monroe at 2:30 p.m.
  • Dr. Phil Mo from Oregon State University will discuss climate change on April 8th at 8:00 p.m.
  • Stars of Dance Chicago will perform on April 23rd at 8:00 p.m.
  • A new lecture by Barry Beish of Caltech on gravitational waves is scheduled for June 15th.
  • An exhibit called "Art of Darkness" from the Dark Energy survey is displayed in the art gallery.
  • Fery Lab functions as a particle physics laboratory offering public tours on Wednesdays at 10:30 a.m.
  • Dr. Josh Freeman, a professor of astronomy and astrophysics, will discuss the Dark Universe.
  • The universe is 13.8 billion years old, with the Earth being 4.5 billion years old.
  • The universe is vast, with the most distant objects being about 30 billion light-years away.

15:47

"Dark Matter's Role in Galaxy Rotation"

  • Rotation speed in kilometers per second plotted against distance from the center of Galaxy M33.
  • Expected rotation curve to show stars orbiting more slowly as distance from the center increases.
  • Ruben and collaborators found stars' rotation speed around a galaxy increases and flattens out at a higher value due to dark matter.
  • Dark matter holds stars in their orbits, with galaxies mostly composed of dark matter.
  • Evidence of dark matter found in individual galaxies through gravitational lensing.
  • Galaxy-galaxy lensing technique used to study typical mass of average galaxies, revealing dark matter halos around luminous galaxies.
  • Dark matter is not made of atoms due to insufficient atom quantities in the universe.
  • Dark matter possibly composed of weakly interacting massive particles (WIMPs), being searched for in experiments worldwide.
  • Possibilities of detecting dark matter particles through collider collisions or WIMP annihilation.
  • Universe's expansion traced back to Edwin Hubble's work, showing galaxies moving away from each other.

32:17

Universe's Expansion Mystery: Dark Energy Dominance

  • The universe began evolving from nearly homogeneous conditions after the big bang, with gravity acting on slight density differences to form large-scale structures known as the cosmic web.
  • A computer simulation of the universe's evolution from homogeneous to inhomogeneous conditions was conducted, focusing on gravity's impact on dark matter particles.
  • The universe started expanding rapidly after the big bang, with cosmic inflation occurring around 380,000 years post-bang, leading to the separation of photons from atoms.
  • The expectation was for the cosmic expansion to gradually slow down over time due to gravity's influence, but in the late 1990s, two teams of astronomers discovered evidence of the expansion speeding up.
  • Type 1A supernovae, explosions of white dwarf stars, were crucial in determining the universe's accelerated expansion, showcasing a consistent intrinsic luminosity.
  • The discovery of the universe's expansion speeding up led to the Nobel Prize in Physics in 2011, challenging previous beliefs about the expansion's trajectory.
  • The universe's acceleration poses a mystery as it defies everyday experiences of gravity, leading to two potential explanations: dark energy or a different behavior of gravity on cosmic scales.
  • The composition of the universe is primarily dark, with dark energy constituting 70%, dark matter 25%, and ordinary matter only 5%, highlighting the dominance of dark components.
  • The relative proportions of dark energy, dark matter, and ordinary matter in the universe change over time as the universe expands, impacting the formation of structures by gravity.
  • Dark energy, possibly the energy of empty space itself, remains a fundamental mystery in physics due to calculations suggesting infinite energy in the vacuum, challenging current theoretical understanding.

48:49

Mapping Universe for Dark Energy Insights

  • Dark energy may be linked to a lighter cousin of the Higgs boson, but this idea is speculative.
  • Siri was consulted for information on dark energy but couldn't provide an answer.
  • Understanding dark energy is crucial for predicting the future evolution of the universe.
  • The Dark Energy Survey aims to map the universe to study the expansion and clumpiness, seeking insights into dark energy.
  • The survey involves taking snapshots of 300 million galaxies and observing supernovae.
  • The project began in 2013 and is supported by the US Department of Energy and the National Science Foundation.
  • Techniques used in the survey include studying galaxy clusters, gravitational lensing, galaxy distribution, and measuring supernovae.
  • Weak gravitational lensing involves measuring the distortion of distant galaxies' shapes due to dark matter.
  • The project involves an international collaboration of 400 scientists using the Blanco telescope in Chile.
  • The telescope's camera has 570 million pixels and uses filters to capture images of galaxies for analysis.

01:05:06

Weekly Supernova Brightness Measurements and Dark Matter Discovery

  • Researchers point towards Supernova once a week to measure brightness.
  • Analyzed data from a green patch, part of a pre-survey science verification.
  • Map shows distribution of galaxies, revealing a filamentary structure of the Cosmic web.
  • Dark matter map created using weak gravitational lensing technique.
  • Recent map covers a thousand square degrees, showing tens of millions of galaxies.
  • Discovered 17 nearby dwarf galaxies rich in dark matter, containing few stars.
  • Gamma ray image from the Fairy Gamay satellite of a dwarf galaxy shows no significant gamma ray excess.
  • Large sky map aids in understanding the solar system, including inner and outer planets.
  • Survey footprint superimposed on known transneptunian objects' orbits, aiding in their detection.
  • Project aims to find optical counterparts to gravitational wave events, potentially from neutron star collisions.

01:21:49

"Gravity, Dark Matter, Galaxies, and Beyond"

  • Gravity is the force exerted by a gravitational field on any moving body within it.
  • Dark matter is a form of mass that causes gravity but is not a force itself.
  • Elementary particle physics involves quarks as the building blocks of matter and forces like gravity.
  • Dark matter is likely a new elementary particle that interacts through gravity.
  • Dark matter does produce gravity, as any form of mass or energy does.
  • The closest galaxy to ours, Andromeda, is about two million light years away.
  • Galaxies are typically separated by a few million light years in space.
  • The universe expanding at 3,000 m per second poses challenges for deep space missions.
  • Andromeda is gravitationally bound to the Milky Way and will eventually merge with it.
  • The study of dark energy was prompted by early indications of the universe's acceleration.

01:39:05

"Universe Expansion, Dark Matter, and Dark Energy"

  • The universe has been expanding since the Big Bang, with periods of acceleration and deceleration, followed by a recent increase in expansion rate.
  • Dwarf galaxies like Triangulum 2 contain mostly dark matter, with ongoing studies to observe them in detail and search for gamma rays indicating dark matter annihilation.
  • Speculation on the end of the universe due to dark energy includes scenarios where gravity weakens, leading to a potential "Big Rip" where dark energy overwhelms all forces, tearing apart particles and atoms.
  • Ongoing surveys aim to reveal more about dark energy, with hopes of significant findings within the next year, potentially shedding light on the nature of dark energy.
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