1.What is the condition of the matter of the universe for an open universe in the future?
i. Equal density to critical density
ii. More density than critical density
iii. Less density than critical density
iv. Less or more density than critical density
Ans: iii. Less density than critical density
2.What percent of the universe is visible to us?
i. 15
ii. 10
iii.95
iv. 5
Ans: iv. 5
3. Who propounded the Big Bang Theory for the origin of the universe?
i. Albert Einstein
ii. Georges Lemaitre
iii. Edwin Hubble.
iv. Pierre Simon
Ans: ii. Georges Lemaitre
4. What is Doppler shift?
i. Shifting of light reaching the earth from distant galaxies beyond the red end of the spectrum
ii. Shifting of light reaching the earth from distant galaxies towards the red end of the spectrum
iii. Shifting of light reaching the earth from distant galaxies left to the red end of the spectrum
iv. Shifting of light reaching the earth from distant galaxies right to the red end of the spectrum
Ans: ii. Shifting of light reaching the earth from distant galaxies towards the red end of the spectrum
5. Which of the following is one of the findings of Hubble’s study about the motion of the heavenly bodies?
i. Milky Way is the heavenly body in which the solar system lies.
ii. Milky Way is the heavenly body which has a black hole at the galactic centre.
iii. Milky Way is not only the galaxy in the universe.
iv. Milky Way is only the galaxy with the solar system.
Ans: iii. Milky Way is not only the galaxy in the universe.
6.Which condition leads the universe to the Big Chill?
i. Geometry of space time is shaped like the surface of a saddle.
ii. Geometry of space time is shaped like a flat surface.
iii. Geometry of space time is shaped like the surface of a sphere.
iv. Geometry of space time is shaped like the surface of a cylinder.
Ans:ii. Geometry of space time is shaped like a flat surface.
7.Distinguish between:
a. Flat universe and closed universe
| Flat universe | Closed universe |
| The curvature of space is neutral or zero, akin to a perfectly flat sheet of paper. | The curvature of space is positively curved, resembling the surface of a sphere. |
| A flat universe suggests that it will continue expanding at a decelerating rate, potentially reaching a stable size in the far future. | A closed universe, due to its positive curvature, implies that after reaching a maximum size, it will contract back, often referred to as a “Big Crunch.” |
| A flat universe can be infinite in extent, suggesting that it has no bounds or edges and stretches indefinitely. | A closed universe, despite its positive curvature, can be finite in extent, analogous to how the surface of a sphere is finite but has no edges. |
b. Flat universe and open universe
| Flat universe | Open universe |
| Space is like a big, flat table-no curves, no bumps. | Space is like a saddle, curving outward, but never closing in. |
| A flat universe expands at a steady speed, like riding a bike at a constant pace. | An open universe expands faster and faster, like coasting downhill on a bike-you speed up but never slow down. |
| The flat universe might go on forever, like a never-ending road stretching into the distance. | The open universe also might stretch endlessly, like a never-ending hallway with doors that lead to more hallway. |
c. Open universe and closed universe
| Open universe | Closed universe |
| An open universe is like a saddle-it curves outward and keeps going in all directions. | A closed universe is like a sphere-it curves in on itself, with no end. |
| The space expands gradually, like a balloon inflating slowly. | It expands, reaches a limit, and then contracts, like a balloon inflating and then deflating. |
| An open universe might go on forever, like an endless field with no fe | A closed universe might loop back on itself, like walking around a circle and ending up where you started. |
8. Define red shift.
Ans:Redshift is when light from faraway things looks more red. It’s because those things are moving away from us. Scientists use redshift to understand how the universe is moving and changing.
9. Introduce the Big Bang Theory.
Ans: The Big Bang Theory is the explanation of how our universe began. It suggests that everything started from a really small, hot, and super dense point around 13.8 billion years ago. Then, it exploded and expanded, forming the universe.
10. What is the future of the universe if the triangle on the surface has an angle whose sum is 180°?
Ans:If the triangle on the surface has an angle whose sum is 180°, it indicates a flat or Euclidean geometry. In this case, the future of the universe is an open-ended expansion, where it keeps growing forever, much like how a flat sheet can extend infinitely without any boundaries or edges
11. What is common in Big Bang Theory and Hubble’s findings?
Ans: The Big Bang Theory and Hubble’s findings have in common is that they explain how the universe began and how it’s changing.
12. Who purposed the theory of relativity?
Ans: The theory of relativity was introduced by a very smart scientist named Albert Einstein.
13. Define singularity.
Ans: Singularity means a point where something, like the center of a black hole or the start of the Big Bang, is incredibly tiny and extremely hot and dense.
14. Give a point which supports that the universe is expanding.
Ans:Stars and galaxies moving away like balloons floating apart! Telescopes show us they’re speeding away, telling us the universe is stretching and getting bigger.
15. What is delicate equilibrium?
Ans: Delicate equilibrium refers to a precise balance or stability in a situation. It’s like when different parts or forces are just perfect, neither too much nor too little, maintaining a steady and harmonious state.
16. What is the role of gravity during nuclear fusion in stars?
Ans: Gravity plays a crucial role during nuclear fusion in stars by pulling together gases and creating immense pressure and heat at the star’s core.
17. Mention the role of gravity in the death of stars.
Ans:Gravity, the cosmic force that pulls things together, is also responsible for a star’s end. When a star uses up its fuel, gravity causes its core to collapse or explode, marking the star’s final moments
18. Define critical density of the universe
Ans:Critical density of the universe is like a cosmic balance point. It’s the exact amount of stuff (matter and energy) needed to determine the universe’s fate.
19. Describe the importance of gravitational force in the universe in short.
Ans: Gravitational force is like the universe’s invisible glue. It brings things together, making planets orbit stars and galaxies stick together. Without it, everything would just scatter and float away. It’s the cosmic force that holds our universe together.
21. What are the findings of Hubble’s study about the motion of the heavenly bodies?
Ans: The findings of Hubble’s study about the motion of the heavenly bodies are:
1.Heavenly bodies, like stars and galaxies, are moving away from each other.
2.The speed of this movement increases with the distance between the heavenly bodies.
3. The discovery implies that the universe is expanding and not static.
4. Hubble’s findings revolutionized our understanding of the structure and history of the universe.
22. Describe the origin of the universe according to Big Bang Theory in short.
Ans: The Big Bang Theory says the universe started very small and very hot around 13.8 billion years ago. Suddenly, it exploded and started growing, cooling down as it expanded.
23. How can we say that the universe is changing continuously?
Ans: We can see the universe changing because stars and galaxies are moving and shifting. Telescopes show us these movements. Also, as time passes, new stars are born, and others die. The universe is always evolving, like a giant, ever-changing cosmic dance.
24. Write a short account on the history of the hypotheses given about the origin of the universe.
Ans: Throughout history, people have had different ideas about how the universe began. Long ago, some believed it was eternal and never had a start. Later, scientists like Edwin Hubble suggested it began with a big explosion, which became the Big Bang Theory. This idea gained traction and is widely accepted today as the most probable explanation for the universe’s beginning. The story of the universe’s origin is like a puzzle—each theory added a piece, and the Big Bang Theory helped complete the picture.
25. Describe the guesses about the future of the universe based on gravitation in short.
Ans: Scientists guess the future of the universe based on gravity. If gravity is strong enough, it could slow down the universe’s expansion and pull things back together. But if there’s less gravity, the universe might keep expanding forever. It’s like a cosmic tug-of-war between gravity’s pull and the universe’s desire to spread out.
26. What is theory of relativity founded by Albert Einstein?
Ans:The theory of relativity, by Albert Einstein, is a really smart idea about how things work when they move, especially when gravity is involved. It helps explain why time can tick slower or faster and how things bend and move in space when there’s a strong force like gravity. It’s like understanding a special set of rules for the way the universe operates.
27. Analyze the future of the earth in the form of Big Crunch.
Ans: The Big Crunch is like a story about the future of Earth and the universe. Imagine if everything, all the galaxies and stars, started coming back together like a giant squeeze. Gravity would pull everything closer and closer until it’s all squished into a very small, hot point.
28. Demonstrate that the expanding universe is the cause of increasing distance between the Milky Way and other galaxies.
Ans:The universe is like a big balloon getting bigger. The Milky Way and other galaxies are like stickers on this balloon. As the balloon expands, the stickers (galaxies) move away from each other because they’re stuck on the stretching surface. Similarly, the universe’s expansion causes galaxies to move away from each other, making their distances increase over time.
29. The galaxies and black holes may disappear in the future.
Ans: In the future, galaxies and black holes might vanish because they’ll spread out and move away from each other due to the universe expanding. As they move farther apart, they might become hard to see or detect.
30. The galaxies and black holes may remain as they are forever.
Ans:The galaxies and black holes might remain as they are forever if the universe’s expansion doesn’t speed up or if it eventually slows down. If the force of gravity can balance the expansion, then galaxies and black holes would stay relatively close, and their structures might remain stable over an incredibly long time.
31. The galaxies and black holes may adjust on a point in the future.
Ans: In the far future, everything might seem to come to a point because the universe is getting bigger. Like dots on an inflating balloon, galaxies and black holes appear to converge, although they are not actually gathering at a single spot.
32. The distance between the earth and the sun increases by 1-2 cm every year.
Ans:The Earth and the Sun drift slightly apart each year due to various forces and movements in space.
33. Gravitation is a must for the origin and death of stars.
Ans:Gravity is essential for both the birth and end of stars. It gathers gas and dust to start a star’s life and, later, collapses massive stars in a supernova, completing their cycle
