# Q about relativistic mass increase, starship

• ContactLight
In summary, the conversation discusses the idea of using antimatter propulsion for a spaceship traveling at relativistic speeds. It is suggested that the mass increase of the ship due to its high speed could be offset by the energy released from the antimatter reaction. However, it is argued that this is not the case and the ratio of the ship's mass to the energy released in the propulsion system would remain the same. Detailed calculations are provided as evidence.
ContactLight
A warning is often given that if one wants to have a spaceship traveling at relativistic speeds (usually to get to another star), the ship's mass increases, making acceleration more difficult. But if it where an antimatter propelled ship, with mass being turned into energy, then wouldn't the mass increase be offset by the increased energy released?

In other words, say you have a best case scenario: it's a positron-electron reaction, producing all gamma rays, which by then we know how to redirect and use, almost 100%, for forward propulsion. So all propellant mass is being turned into energy, almost all of which is being spent on forward propulsion. Isn't the propellant mass increasing, along with the whole ship's mass, and so the ratio of ship's mass to energy being released in the "combustion chamber" always the same?

No. The easiest way to see this is to not even use the concept of "relativistic mass". For detailed calculations, see for instance

http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html

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This is a very interesting question and one that has been debated among physicists and engineers for quite some time. The concept of relativistic mass increase is a fundamental principle in Einstein's theory of relativity, which states that as an object's velocity approaches the speed of light, its mass increases. This increase in mass results in a higher amount of energy required to accelerate the object, making it more difficult to reach relativistic speeds.

However, your idea of using antimatter propulsion to offset the mass increase is a valid one. Antimatter reactions, such as positron-electron reactions, do release a tremendous amount of energy and can potentially provide enough thrust to counteract the increase in mass. In this scenario, the ratio of the ship's mass to the energy being released would remain constant, as you pointed out.

However, there are a few things to consider. Firstly, the technology to harness and control antimatter reactions is still in its infancy and is currently not feasible for practical use in space travel. Additionally, the amount of antimatter required for propulsion would be massive and extremely expensive to produce. It would also pose significant safety concerns, as even a small amount of antimatter coming into contact with regular matter could result in a catastrophic explosion.

Furthermore, even if we were able to overcome these challenges and use antimatter propulsion, the relativistic mass increase would still have an impact on the efficiency and speed of the ship. While it may help offset the increase in mass, it would not eliminate it entirely. The ship would still experience a significant increase in mass as it approaches relativistic speeds, making it more difficult to accelerate and requiring even more energy.

In conclusion, while your idea of using antimatter propulsion to offset the relativistic mass increase is intriguing, it is currently not a practical or feasible solution for interstellar travel. The concept of relativistic mass increase is a fundamental principle of physics, and while it may present challenges for space travel, it is something that we must take into account and work around in our pursuit of exploring the universe.

## What is relativistic mass increase?

Relativistic mass increase, also known as relativistic mass dilation, is the concept that an object's mass appears to increase as its velocity approaches the speed of light.

## How does relativistic mass increase affect a starship?

If a starship were to travel at speeds close to the speed of light, its mass would appear to increase significantly, making it more difficult to accelerate and requiring more energy. This can also have an impact on the ship's fuel consumption and overall performance.

## Can a starship actually reach the speed of light?

According to the theory of relativity, it is impossible for any object with mass to reach the speed of light. This is due to the increase in mass and the infinite amount of energy required to accelerate an object to the speed of light.

## What are some proposed methods for overcoming the effects of relativistic mass increase on a starship?

One proposed method is to use a fuel source that is constantly replenished, such as nuclear fusion. Another idea is to use a form of propulsion that does not require the use of propellant, such as a solar sail or a hypothetical "warp drive". Further research and technological advancements are needed to make these methods feasible.

## What are some potential consequences of relativistic mass increase on a starship?

Aside from the difficulty in reaching high speeds and the impact on fuel consumption, relativistic mass increase can also have an effect on time dilation. As the ship's velocity increases, time for those on board would appear to slow down compared to those on Earth, potentially resulting in significant differences in age and experiences upon returning to Earth.

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