Is Interstellar Travel Impossible?
In a vast galaxy with billions of planets existing for billions of years, there is no evidence of technological civilizations that existed before us. This is known as the Fermi Paradox, and it has many potential explanations. Some believe that we are among the first to overcome some evolutionary challenges while others believe that every civilization reaching our level of advancement destroys itself.
The idea that interstellar space wants to murder us is the most concerning. The space between the stars in our galaxy is full of gas and dust grains which at relativistic speeds can become deadly. This is a potential dealbreaker for the future of our civilization as a galactic species.
The average gas density of interstellar space is around 1 atom per cubic centimeter while the dust consists of silicate and carbonaceous molecules that have clumped together into grains with most of them being between a tenth to a few tenths of a micrometer across. Despite being sparse, even the smaller grains occur at a rate of 1 grain per 100-meter cube.
Interstellar travel is becoming more plausible, especially in terms of ship survival during the journey. Shielding is necessary for nearby stars and repairing it can help reach more distant parts of the galaxy. However, radiation presents a subtle hazard that could result in a perfectly intact ship carrying a dead crew upon arrival at the destination. To reach near-light speeds, the ship needs several meters of titanium or tens of meters of water, which make spacewalks outside of the ship impossible. Unfortunately, this shielding does not protect against cosmic rays, that although lower than the interstellar gas radiation, can significantly increase cancer risks during a 4-year journey.
In the last two episodes, we delved deeper into topics such as how quantum mechanics can be derived as a model of our information about the world. We also covered a new idea that might solve the black hole information paradox involving a pretty crazily abstract idea, including imaginary replica black holes connected by virtual wormholes. Clay Farris Naff asks whether Zeilinger's description of informational quantum mechanics is consistent with Hawking's late in life antirealist stance.
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