Question

The amount of energy that would be needed to accelerate a large spaceship to a speed close to the speed of light is (a) about 100 times as much energy as is needed to launch the Space Shuttle; (b) more than the total amount of energy used by the entire world in a year; (c) more than the amount of energy that our Sun emits into space in a year.The rocket engines of our current spacecraft are powered by (a) chemical energy; (b) nuclear energy; (c) matter-antimatter annihilation.

Short answer

The energy needed is more than the Sun emits in a year; rocket engines currently use chemical energy.

Step-by-step solution

Understanding Energy Needed for Space Travel

The scenario involves accelerating a large spaceship to speeds close to the speed of light. Using Einstein’s theory of relativity, the energy required to accelerate an object to near-light speeds is immense due to the increase in mass that occurs as speed approaches the speed of light. Hence, the amount of energy needed would be much greater than any energy currently generated on Earth.

Assessing Energy Options

Let's examine the provided options: (a) is about 100 times as much energy as needed to launch the Space Shuttle; however, near-light speed travel requires vastly more energy. (b) is more than the total amount of energy used by the entire world in a year; this is a significant amount but still could be conceivable. (c) is more than what our Sun emits in a year; this comparison makes sense due to the enormous energy involved.

Identifying Current Rocket Energy Sources

We also need to consider what type of energy is used in our current rocket engines: (a) Chemical energy is most common in current rocket propulsion systems like those used in chemical rockets. (b) Nuclear energy has been proposed for future space travel but isn't common now. (c) Matter-antimatter annihilation isn't a practical energy source yet with current technology, although it offers the greatest energy output per mass.

Concluding Based on Energy Requirements and Sources

To reach near-light speeds, option (c) from the energy requirements is most likely due to the colossal energy it describes relative to solar emissions. For propulsion systems, option (a) on chemical energy is what is used in present-day spacecraft.

Key concepts

Energy Requirements in Space Travel

When it comes to traveling through space at speeds approaching the speed of light, the energy demands become astronomically high.
This is due to Einstein's mass-energy equivalence principle, where as an object’s speed increases, so does its relativistic mass.
Consequently, the energy needed for acceleration also increases tremendously. Imagine a large spaceship aiming to travel at a significant fraction of the speed of light.
The energy required is not just a bit more than what we're used to—it is enormous.
- It vastly exceeds the energy needed to launch the Space Shuttle by over 100 times. - It surpasses the total annual energy consumption of the entire world. - In fact, it even rivals or exceeds the total energy output of the Sun in a year.
Thus, efforts to achieve such rapid speeds would necessitate harnessing energy on a scale that is currently unfathomable with our present-day technology.

Einstein’s Theory of Relativity

Einstein’s Theory of Relativity is foundational to understanding why high-speed space travel demands such tremendous energy.
The theory includes two main parts: Special Relativity and General Relativity. Each part contributes to how we perceive space travel. Special Relativity, introduced in 1905, tells us that the laws of physics are the same for all observers in uniform motion, and the speed of light in a vacuum is a universal constant.
The most famous consequence of this theory is the equation $$E=m{c}^2$$ Here, $E$ is the energy, $m$ is the mass, and $c$ is the speed of light.
This equation reveals that energy and mass are interchangeable, meaning as a spaceship speeds up and approaches the speed of light, its effective mass increases, necessitating more energy for further acceleration.Understanding Special Relativity is crucial for evaluating the energy needs for near-light speed travel. Without considering these relativistic effects, our estimations would fall drastically short.

Current Rocket Propulsion Systems

In today's space travel, chemical energy is the predominant source of propulsion.
The rockets we see launching payloads into space mainly rely on the combustion of chemical fuel. This energy source is well-understood yet limited in terms of the speed and distances it can achieve.

• Chemical Propulsion: Utilizes the exothermic reaction of fuel and an oxidizer to produce thrust. This is how most of our rockets, like the Space Shuttle, operate.
• Nuclear Propulsion: Although not commonly used in current spacecraft, nuclear energy offers the promise of higher efficiency and longer missions. It remains a concept for future space exploration missions.
• Matter-Antimatter Annihilation: Providing the highest energy output per mass, this method is largely theoretical with existing technology. It consists of the complete conversion of matter into energy, which presents vast potential for propelling spacecraft at incredible speeds.

These propulsion methods show the range of possibilities and limitations for contemporary space travel. While chemical propulsion is mostly what we see today, future advancements might harness nuclear or even matter-antimatter reactions for far-reaching interstellar journeys.