Entropy is a measure of a. light b. reactivity c. randomness
In physics, a “system” is a. a group of subatomic particles b. a mix of different chemicals c. any collection of objects
For one system to _______ in entropy, another system has to _________ in entropy. a. increase, decrease b. decrease, increase c. decrease, decrease
Discussion/essay questions
Some scientists believe that the universe could be part of an even bigger system of universes. Do you think it is possible that there are other universes out there? Why or why not?
Transcript
Entropy is an important concept in physics. It measures the amount of randomness in a system. A system is any collection of objects. It can mean a few molecules or the entire universe. The second law of thermodynamics states that entropy always increases. A system can only decrease in entropy if it causes another system to increase in entropy. This is because there are always more possible states of chaos than states of order. As a result, the universe will always get more random and disordered over time. For example, there are only a few ways to clean a messy room, and it takes a lot of work. However, it is easy to mess up a clean room, and there are infinitely many ways to do it. Increasing entropy is the reason that glasses shatter but never put themselves back together. It is also the reason humans get older but never younger. Because entropy always increases, we can only experience time in one direction.
Neutrinos are hard to find because a. they react with most substances b. they have no mass at all c. they rarely interact with other matter
Most of the neutrinos that reach Earth come from a. nuclear power plants b. radioactive substances c. the Sun
Neutrinos are a. the rarest type of particle in the universe b. the most common type of particle in the universe c. the second most common type of particle in the universe
Discussion/essay questions
Scientists study particles like neutrinos to find out how and why the universe formed the way it did. Do you think it is possible to fully understand what happened at the beginning of time? Why or why not?
Transcript
Neutrinos are tiny particles that are produced when atoms split, fuse, or decay. They are sometimes called “ghost particles,” because they are very difficult to detect. Neutrinos are so small that they rarely interact with other matter. Trillions of neutrinos pass through our bodies every second without touching us at all. Most of the neutrinos that reach Earth come from the Sun. They are a byproduct of nuclear fusion, which is the process the Sun uses to create energy. However, neutrinos are also produced in nuclear reactors, as well as radioactive substances. There are three types of neutrinos, and they each interact with different particles. Neutrinos can even change their type as they travel. Although they are hard to find, neutrinos are actually the second most common type of particle in the universe. They are only outnumbered by particles of light.
A quasar is a. a massive and luminous galaxy b. a star that emits an unusual amount of radio waves c. a bright galactic nucleus powered by a black hole
Scientists first discovered quasars in a. 1913 b. 1931 c. 1961
Most quasars are a. billions of light years away b. close to the Milky Way Galaxy c. almost as old as the universe
Discussion/essay questions
What do you think the purpose of studying space is? Why do humans want to understand the universe?
Transcript
A quasar is a celestial object that emits enough radiation to glow brighter than a galaxy. The energy that a quasar emits comes from a supermassive black hole at its centre. When scientists first observed quasars in 1961, they thought they were stars, or star-like objects. The name “quasar” is an abbreviation for “quasi-stellar radio source”, because the first observed quasars looked like stars that emitted lots of radio waves. Scientists now know that quasars are the nuclei of young galaxies. Even though quasars are very bright, most of them are billions of light years away, which means that observing them can provide information about the state of the universe in the distant past. The oldest discovered quasar formed nearly 13 billion years ago, at the very beginning of the universe’s life.
The universe is about a. 4.5 billion years old b. 13 billion years old c. 50 billion years old
Fermi thought that if older civilizations existed, a. they should have contacted us already b. they wouldn’t be friendly to us c. they would have destroyed each other
The Great Filter is a. a hypothetical barrier that stops life from developing b. a hypothetical type of technology for interstellar travel c. a hypothetical civilization that has the power to contact other civilizations
Discussion/essay questions
Do you believe in life on other planets? If so, why do you think they haven’t contacted us? If not, what makes you think we’re alone?
Scientists who believe in the Great Filter are not sure if we are past it. What could stop life on Earth from developing further?
Transcript
The Fermi paradox is based on a question asked by a scientist named Enrico Fermi: if the universe is so large, why haven’t we found intelligent life yet? Although it is a very simple question, it has confused scientists for decades. The universe has existed for over 13 billion years, but our planet is only about 4.5 billion years old. Fermi believed that if human life could develop so quickly, there surely had to be older, more advanced civilizations out there. These civilizations likely would be capable of interstellar travel. If this is true, then aliens should have contacted us already. Many people have proposed explanations since Fermi first asked the question in 1950. One possibility is something called a Great Filter, which is a hypothetical barrier that stops most types of life from developing past a certain point.
Dark energy is a force that exists throughout the universe. It is believed to make up about 68% of everything that exists, and it affects the way the universe is expanding. have known about the expansion of the universe since 1929. But for many years, most believed that the force of gravity would eventually slow down this expansion. However, in the 1990s, a team of astronomers that the universe was actually expanding than it had been years before. They came to the conclusion that there was another force, called dark energy, that was causing the expansion to accelerate. Dark energy is even than gravity, and scientists still don’t know much about it. It has often been called the universe’s greatest mystery.
Comprehension questions
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Discussion/essay questions
There is a lot to learn about the universe. If you could ask an astronomer any question, what would you ask?
Transcript
Dark energy is a mysterious force that exists throughout the universe. It is believed to make up about 68% of everything that exists, and it affects the way the universe is expanding. Scientists have known about the expansion of the universe since 1929. But for many years, most believed that the force of gravity would eventually slow down this expansion. However, in the 1990s, a team of astronomers observed that the universe was actually expanding faster than it had been years before. They came to the conclusion that there was another force, called dark energy, that was causing the expansion to accelerate. Dark energy is even stronger than gravity, and scientists still don’t know much about it. It has often been called the universe’s greatest mystery.
Redshift is one example of how reality can depend on our interpretation. While an observer standing still might be able to see an object change colour, an observer moving at the same speed as the object would not. Can you think of some other situations where different people might interpret reality differently?
Transcript
Redshift is an effect created by light waves. It causes the colour of an object to become redder as it moves away from an observer. This is because red light has the longest wavelength of all the colours on the visible spectrum. Redshift is not something that humans often see, because an object must be travelling very fast to visibly change colour. However, we can observe a similar effect with sound waves, when the pitch of a car horn changes as the car drives away. Redshift is important because it has helped astronomers make observations about the universe. In 1929, the redshift of galaxies caused astronomer Edwin Hubble to discover that the universe is expanding. Today, astronomers also use redshift to find the locations of planets outside of our solar system.
In 1928, British physicist Paul Dirac the existence of antimatter. His theory was that every type of subatomic particle had an antiparticle. He believed that an antiparticle would be almost identical to a normal particle, only with an electrical charge. This theory was proven two years later, when American physicist Carl David Anderson discovered a positively-charged electron, later named the “positron”. Today, physicists know that our is made up of both matter and antimatter. They have even successfully created antimatter atoms. However, antimatter is still one of the greatest in the universe. Scientific theory states that the Big Bang should have created equal amounts of matter and antimatter. The problem with this idea is the fact that matter and antimatter instantly destroy each other when they come into contact. This means that if the Big Bang had as much antimatter as it did matter, the universe would not exist today.
Comprehension questions
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Discussion/essay questions
For years, scientists have debated the reason why our universe has more matter than antimatter. Some scientists have even suggested the idea that the Big Bang created another, parallel universe, made up mostly of antimatter. However, there isn’t a lot of evidence for this. Do you think scientists will ever know the answer to this question, or are there just some things about the universe we will never understand?
Transcript
In 1928, British physicist Paul Dirac predicted the existence of antimatter. His theory was that every type of subatomic particle had an antiparticle. He believed that an antiparticle would be almost identical to a normal particle, only with an opposite electrical charge. This theory was proven two years later, when American physicist Carl David Anderson discovered a positively-charged electron, later named the “positron”. Today, physicists know that our universe contains both matter and antimatter. They have even successfully created antimatter atoms. However, antimatter is still one of the greatest mysteries in the universe. Scientific theory states that the Big Bang should have created equal amounts of matter and antimatter. The problem with this idea is the fact that matter and antimatter instantly destroy each other when they come into contact. This means that if the Big Bang had created as much antimatter as it did matter, the universe would not exist today.
While most scientists today agree that the universe was created by a Big Bang, some have other theories. Do you believe that the Big Bang theory is the correct explanation? Why or why not?
Transcript
The Big Bang theory is a theory scientists use to explain the creation of the universe. The theory states that all of the matter in the universe began to expand from one single point. This idea was first proposed by astronomer Georges Lemaître in 1927. He received evidence to support his theory when another astronomer named Edwin Hubble observed that galaxies seemed to be moving away from each other. This was an indication that the universe was expanding. Because of this new information, Lemaître concluded that the universe must have once been smaller and denser. According to the theory, the universe began as something known as a singularity, which is an area where matter is infinitely dense. Over 13 billion years ago, this singularity began to expand, and the matter inside it formed atoms that would later form stars and planets. Lemaître’s idea received a lot of criticism, because most scientists at the time believed that the universe had existed forever. However, throughout the 20th century, scientists continued to find proof that Lemaître’s theory was accurate. Today, the Big Bang theory is the most widely accepted explanation for how the universe was created.
