ClassX Video Lessons Youtube Channel Science Time Neil deGrasse Tyson: What is Dark Matter? What is Dark Energy?
Have you ever gazed up at the night sky and wondered what the universe is made of? This question has intrigued humans for centuries. Today, we understand that the universe is composed of three main components: regular matter, dark matter, and dark energy. Regular matter includes the atoms that form stars, planets, and everything we can see. But what about the rest?
When scientists observe the universe, they notice that the gravitational pull we see doesn’t add up with just the visible matter. This discrepancy led to the hypothesis of dark matter, an invisible substance that provides the extra gravity needed to explain the universe’s structure. Although we can’t see dark matter, its presence is inferred from its gravitational effects on visible matter.
For over sixty years, NASA and its international partners have been using advanced telescopes and satellites to explore the universe’s evolution, from the Big Bang to today. The cosmic microwave background, a remnant of the Big Bang, provides clues about the universe’s early moments. The Wilkinson Microwave Anisotropy Probe helped determine the universe’s age to be about 13.77 billion years and revealed that regular atoms make up only 4.6% of the universe. The rest is dark matter and dark energy.
In the universe’s early days, there were no stars or galaxies. Over time, stars formed, and galaxies began to cluster, held together by gravity. However, galaxies rotate at speeds that suggest more mass than we can see, hinting at dark matter’s presence. Particle physicists propose that dark matter consists of exotic particles that don’t interact with light, making them invisible but still exerting gravitational influence.
Some theories even suggest that dark matter might not be matter at all but could be gravitational effects from a parallel universe in a multiverse. While this idea is still speculative, it opens up fascinating possibilities for understanding our universe.
Dark energy is another mysterious component of the universe, making up about 68% of its total content. Observations from the Hubble Space Telescope have shown that the universe’s expansion is accelerating, contrary to earlier beliefs. This acceleration is attributed to dark energy, a mysterious force that seems to be pushing galaxies apart.
Dark matter accounts for roughly 27% of the universe, while the remaining 5% includes everything we can see and touch. Despite decades of research, dark matter and dark energy remain elusive, but scientists are developing new methods to detect them, potentially leading to groundbreaking discoveries.
Astrophysicists can measure phenomena even without fully understanding their causes. For instance, they can track the movement of celestial bodies without knowing the exact mechanics. Similarly, they measure the effects of dark matter and dark energy, even if their true nature is still a mystery.
Rebecca Liane, an astroparticle physicist at Stanford University, suggests that Jupiter could be a prime candidate for detecting dark matter due to its large surface area. In 2021, she conducted a gamma-ray analysis of Jupiter using data from the Fermi Telescope, although no dark matter was detected.
Scientists are also considering using exoplanets as dark matter detectors. According to Yuri Smirnov, a particle theorist at Ohio State University, when exoplanets capture dark matter, it could travel to their cores, releasing energy as heat. This heat might be detectable by NASA’s James Webb Space Telescope, which aims to succeed the Hubble Space Telescope.
In 2025, NASA plans to launch the Roman Space Telescope, designed to explore dark energy and dark matter, search for exoplanets, and investigate various topics in infrared astrophysics. If successful, this mission could lead to transformative discoveries, reshaping our understanding of the universe and our place within it.
Thank you for exploring the mysteries of the universe with us! Stay curious and keep looking up at the stars.
Engage in a structured debate with your classmates about the nature of dark matter. Divide into two groups: one supporting the idea that dark matter is composed of exotic particles, and the other proposing alternative theories such as gravitational effects from a parallel universe. Use evidence from recent research to support your arguments.
Work in pairs to analyze data from the cosmic microwave background (CMB). Use online simulators or datasets from NASA to explore how the CMB provides clues about the universe’s early moments. Present your findings in a short presentation, highlighting how this data supports the existence of dark matter and dark energy.
Design a hypothetical experiment to detect dark energy. Consider the tools and technologies you would need, such as telescopes or satellites. Outline the steps you would take and the challenges you might face. Share your experimental design with the class and discuss its feasibility.
Research the potential of using exoplanets as dark matter detectors. Write a short report on how capturing dark matter could release detectable heat in exoplanets. Discuss the role of the James Webb Space Telescope in this research and the implications of such discoveries.
Create a proposal for a future space mission aimed at exploring dark matter and dark energy. Include objectives, potential instruments, and expected outcomes. Present your proposal to the class, simulating a pitch to a space agency for funding and support.
**Sanitized Transcript:**
What is the universe made of? This is a question that humans have been asking since we first looked up into the night sky. The universe is thought to consist of three types of substance: regular matter, dark matter, and dark energy. Regular matter consists of the atoms that make up stars, planets, human beings, and every other visible object in the universe.
When we observe the universe, we see the effects of gravity and try to account for it by adding up all the stars, galaxies, planets, comets, and black holes. The addition of dark matter, which provides extra gravity, helps us understand the universe as we see it. While we don’t know what dark matter is, we know it’s there because we can’t explain the universe’s structure without it.
In the last six decades, NASA, along with its international partners and thousands of researchers, has expanded our knowledge of the universe using a fleet of telescopes and satellites. They have been exploring the evolution of the universe from the Big Bang to the present. The cosmic microwave background provides a record of the earliest moments of the Big Bang. After some time, the first stars formed, leading to the creation of galaxies, which matured over billions of years.
The Wilkinson Microwave Anisotropy Probe satellite returned data that allowed astronomers to assess the age of the universe to be approximately 13.77 billion years old. It also determined that atoms make up only about 4.6 percent of the universe, with the remainder being dark matter and dark energy.
For the first 150 million years after the Big Bang, there were no galaxies, stars, or planets. As time passed, the first stars formed, and galaxies began to cluster together. Our solar system, along with galaxies and clusters of galaxies, is held together by gravity. However, galaxies appear to be rotating at such speeds that the gravity generated by their observable matter could not possibly hold them together, suggesting the presence of unseen forces.
Particle physicists believe that dark matter might be composed of exotic particles that do not interact with light, making them invisible to our telescopes but still exerting gravitational influence. This mysterious substance is thought to make up the bulk of a galaxy’s mass and forms the foundation of the universe’s large-scale structure.
Dark matter does not emit, absorb, or reflect light; its presence is only known through its gravitational pull on visible matter. Some theories suggest that dark matter may not be matter at all, but rather the gravitational influence from ordinary matter in a nearby universe within a multiverse. While we lack direct data for this, there are theoretical and philosophical reasons to consider the existence of a multiverse.
NASA telescopes have helped us better understand this invisible matter, which is estimated to be five times the mass of regular matter. The first direct detection of dark matter was made in 2007 through observations of the Bullet Cluster of galaxies by the Chandra X-ray Telescope.
Another intriguing phenomenon observed by the Hubble Space Telescope is that distant supernovae indicated that the universe was expanding more slowly in the past than it is today. However, the expansion of the universe has been accelerating, contrary to previous expectations. This acceleration is attributed to a mysterious pressure in the vacuum of space, which we refer to as dark energy.
Approximately 68 percent of the universe is thought to be dark energy, while dark matter makes up about 27 percent. The remaining matter, which includes everything on Earth and all normal matter observed, accounts for less than five percent of the universe.
The universe remains far from fully understood, and scientists have been searching for these elusive entities for decades. Recently, new methods for detecting dark matter and dark energy have been developed, which could lead to significant breakthroughs in our understanding of the universe.
In astrophysics, scientists can measure phenomena even if they don’t fully understand their causes. For example, they can observe objects falling to the ground or the movement of the sun across the sky without knowing the underlying mechanics. Similarly, scientists measure the effects of dark matter and dark energy, even if their exact nature remains elusive.
Rebecca Liane, an astroparticle physicist at the SLAC National Accelerator Laboratory at Stanford University, believes that Jupiter is an ideal candidate for detecting dark matter due to its large surface area. In April 2021, she presented the first dedicated gamma-ray analysis of Jupiter, using data from the Fermi Telescope, which showed evidence of an astrophysical source of gamma rays, although no signs of dark matter were found.
Scientists are also exploring the potential of using exoplanets as dark matter detectors. According to Yuri Smirnov, a particle theorist at Ohio State University, this approach does not require new instruments. When the gravity of exoplanets captures dark matter, it travels to the planetary core, where it annihilates and releases energy as heat. This heating could be measured by NASA’s James Webb Space Telescope, which is set to launch soon and aims to succeed the Hubble Space Telescope.
In 2025, NASA plans to launch the Roman Space Telescope, designed to explore dark energy and dark matter, search for exoplanets, and investigate various topics in infrared astrophysics. If successful, this mission could lead to groundbreaking discoveries that may change our understanding of our existence in the universe.
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Dark Matter – A form of matter that does not emit, absorb, or reflect light, making it invisible and detectable only through its gravitational effects on visible matter. – Scientists are using gravitational lensing to map the distribution of dark matter in the universe.
Dark Energy – A mysterious form of energy that is hypothesized to be responsible for the accelerated expansion of the universe. – The discovery of dark energy has led to new theories about the ultimate fate of the universe.
Universe – The totality of space, time, matter, and energy that exists, including all galaxies, stars, and planets. – The Big Bang theory describes the origin and evolution of the universe from a singular point.
Gravity – A fundamental force of nature that causes objects with mass to be attracted to one another. – Einstein’s theory of general relativity revolutionized our understanding of gravity by describing it as the curvature of spacetime.
Galaxies – Massive systems composed of stars, stellar remnants, interstellar gas, dust, and dark matter, bound together by gravity. – The Milky Way and Andromeda are two of the largest galaxies in our local group.
Astrophysics – The branch of astronomy that deals with the physical properties and processes of celestial objects and phenomena. – Astrophysics seeks to understand the life cycles of stars and the dynamics of galaxies.
Particles – Small constituents of matter, such as protons, neutrons, and electrons, which are the building blocks of atoms. – Particle physics experiments at CERN aim to uncover the fundamental particles that make up the universe.
Expansion – The increase in distance between objects in the universe over time, driven by the metric expansion of space. – The observation of redshift in distant galaxies provides evidence for the expansion of the universe.
Telescopes – Instruments that collect and magnify light or other forms of electromagnetic radiation to observe distant celestial objects. – The Hubble Space Telescope has provided unprecedented views of the cosmos, leading to numerous discoveries.
Exoplanets – Planets that orbit stars outside our solar system, often detected through methods such as transit photometry or radial velocity. – The discovery of exoplanets in the habitable zone of their stars raises the possibility of finding extraterrestrial life.
