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| The leading theory on how the universe started and continues to evolve to this day is called the ________ theory. | Big Bang |
| Evidence suggests that the Universe ______ years old. | 13.8 billion |
| A well-tested explanation that unifies a broad range of observations is called a(n) ______. | scientific theory |
| TRUE or FALSE: A scientific theory is basically just a hypothesis because it hasn't been tested yet. | FALSE (In order to gain the status of a scientific theory, it had to have been extensively tested and is backed up with enough data that the overwhelming majority of scientific experts on the topic conclude that the theory is the best current explanation for something based on all available evidence. A scientific theory is not just an untested hypothesis)) |
| TRUE or FALSE: A scientific theory is a fact and can't be changed or modified. | FALSE (All theories can be changed or modified if new evidence comes to light) |
| The study of the origin, structure, and future of the universe is called _______. | cosmology (Do not get this confused with "cosmetology" which is the professional skill or practice of beautifying the face, hair, and skin.) |
| Just before the universe started to expand, all the energy in the Universe today was in one tiny spot. That spot was called a(n) _______. | singularity |
| TRUE or FALSE: In the tiniest fractions of a second during which the universe first started to expand, there was energy but no matter. | TRUE (It wasn't until a tiny fraction of a second later that a lot of this pure energy was transformed into matter, as predicted by Einstein's equation E=mc^2) |
| TRUE or FALSE: Matter can be transformed into energy, but energy can't be transformed into matter. | FALSE (Matter can be transformed into energy and energy can be transformed in matter) |
| In Einstein's famous equation, E = mc^2, the E stands for _____, the m stands for ______ and the c stands for _____. | Energy, mass, speed of light |
| TRUE or FALSE: When energy first turned into matter a fraction of a second after the start of the universe, protons and neutrons were the first particles of matter created. | FALSE (only tiny fundamental particles like quarks and leptons were created. The universe would have to cool a little more over the first full second of existence before these fundamental particles could slow down enough to stick together and form protons and neutrons) |
| The three basic particles that make up an atom are positively charged _______ and neutrally charged _______ in the nucleus surrounded by much smaller negatively charged particles called ______ that formed a swarming cloud around the nucleus. | protons, neutrons, electrons |
| Out of the 4 basic forces, the force of _______ is the force responsible for attracting large objects together. | gravity |
| Out of the 4 basic forces, the ___________ force is the force that attracts oppositely charged particles and repels particles of the same charge. | electromagnetic |
| Out of the 4 basic forces, the _______ force is the force that allows protons and neutrons to stick together and form a nucleus even though protons repel each other because they have the same charge. | strong nuclear force |
| Out of the 4 basic forces, the _______ force is the force that is responsible for radioactive decay of the nucleus in radioactive elements. | weak nuclear force |
| By _________ after the Big Bang, the universe had cooled just enough for the fundamental particles to start coming together to form protons and neutrons. | 1 second |
| By _________ after the Big Bang, the universe had cooled enough for protons and neutrons to start sticking together to form the first atomic nuclei. | 3 minutes |
| When protons and neutrons first started sticking together to form atomic nuclei, the nuclei that were formed were about 75% ______ and 25% ______. | hydrogen, helium |
| By _________ after the Big Bang, the universe had cooled to the point where nuclear fusion could no longer take place and the nuclei of hydrogen and helium stopped forming (at least until 200 million years later when stars started forming) | 20 minutes |
| The type of nuclear reactions that cause the protons and neutrons in the nuclei of smaller elements to stick together and form bigger elements are called _____ reactions. | fusion |
| By _________ after the Big Bang, the universe had cooled enough for electrons to be able to settle around the nuclei of hydrogen and helium to form the first complete atoms. | 380,000 years |
| By 380,000 years after the Big Bang, the universe had cooled enough for _______ to be able to settle around the nuclei of hydrogen and helium to form the first complete atoms. | electrons |
| When the universe had expanded and cooled to the point where electrons could finally settle into orbitals around the nuclei of hydrogen and helium, a tremendous burst of light was given off. This burst of light is still detectable as the _____. | Cosmic Background Radiation (Can also be called the Cosmic Microwave Background),  |
| This photo is a photo of _____., | the Cosmic Background Radiation (This is an image of the microwave radiation left over from a time shortly after the big bang when the first complete elements formed when the universe was 380,00 years old. When the universe finally cooled to the point where electrons could settle around the nuclei of hydrogen and helium, a great burst of light was released. This photo is showing light from this event that is finally reaching us and has been red shifted into the microwave range), |
| By _________ after the Big Bang, the earliest stars in the Universe were starting to form. | 200 million years |
| For the first stars to form, gravity had to clump the gases in the universe into dense masses and compress them enough to get hot enough for __________ reactions to occur. | nuclear fusion |
| For the first stars to form, ______ had to clump the gases in the universe into dense masses and compress them enough to get hot enough for nuclear fusion reactions to occur. | gravity |
| For helium nuclei (atomic # = 2) to form during the first 20 minutes of the universe, a ______ nucleus would have to fuse with a ______ nucleus. | hydrogen, another hydrogen (Since each hydrogen nucleus has an atomic number of one, if two hydrogen nuclei fuse, they will now have an atomic number of 2, meaning that the new nucleus has 2 protons. The only element with 2 protons in it's nucleus is helium. Check your periodic table to verify that helium is the only element with an atomic number of 2) |
| During the first 20 minutes of the universe, a tiny amount of lithium nuclei (atomic # = 3) formed by nuclear fusion of a ______ nucleus with a ______ nucleus. | hydrogen, helium (Since a hydrogen nucleus has an atomic number of one and a helium nucleus has an atomic number of 2, if a hydrogen nucleus fuses with a helium nucleus, the new nucleus will now have an atomic number of 3, meaning that the new nucleus has 3 protons. The only element with 3 protons in it's nucleus is lithium. Check your periodic table to verify that lithium is the only element with an atomic number of 3) |
| The fact that the cosmic background radiation (pictured here) was not completely uniform when it got sent out 380,000 years after the Big Bang is explained by the fact that matter had _____., | already started to clump together by the time this radiation was released, |
| Hubble's Law states that other galaxies in the universe are moving away from us and the farther away the object is, the _____ it is moving away from us. | faster |
| Observations of galaxies and the amount their light is red-shifted indicate that everything in the universe is moving away from _____. | a center point (Based on the speed and direction of the movement of galaxies, it is apparent that if things were to reverse direction, they would meet back up at this center point at the same time and it would take 13.8 billion years to do so) |
| A large oval track that allows scientists to accelerate sub-atomic particles to speed close to the speed of light and then smash them together to learn about conditions present early in the Big Bang plus the composition of matter is called a(n) _____. | Particle Collider (These are also sometimes called Particle Accelerators) |
| Experiments in Particle Colliders predict that the first elements formed during the Big Bang would be _____. | Hydrogen and helium (This prediction is supported by evidence because the composition of the universe is still mostly hydrogen and helium. Also, looking back in time at the earliest stars to form in the universe shows that they are made almost completely of hydrogen and helium. We can look back in time because light from the earliest stars that are the farthest away from us was sent out over 13 billion years ago and is only reaching us now.) |
