Scientific Martyrs, Life Beyond Our Planet & More! | Cosmic Queries #106

Giordano Bruno, a 16th-century monk, was executed for his 'heretical' idea that stars in the night sky could be other suns with their own planets, potentially harboring life. This concept directly challenged the theological view that Earth was the sole object of God's creation, leading to his burning at the stake.

Bruno read Copernicus's work, which placed the Sun at the center, not Earth. He reasoned if Earth is a planet with life, other stars might also have planets with life. This was deemed heretical because it implied Earth was not unique in God's creation.

Light travels at its maximum speed in a vacuum. When it enters a medium like air, glass, or water, its average speed decreases. This is not because the photons themselves slow down, but because they constantly interact with the medium's molecules, effectively taking detours and pauses before continuing at light speed between interactions. This average slowing is quantified by the 'index of refraction.'

Analogy of walking through a crowded New York City street: you move at full speed between people but are slowed by constant interactions. The index of refraction (e.g., diamond is 2.4) directly relates to this slowing (light in diamond travels ~40% of its vacuum speed).

When light passes from a denser medium to a less dense one, it bends. If the angle of incidence is steep enough, the light will not enter the second medium at all but will instead reflect entirely back into the first medium. This phenomenon is called total internal reflection and is crucial in fiber optics and other optical systems.

As the angle of light entering a new medium becomes steeper, the bending increases until a critical angle is reached where the light reflects back into the original medium.

LIGO (Laser Interferometer Gravitational-Wave Observatory) detects gravitational waves by using two long, perpendicular laser arms. A passing gravitational wave stretches space-time, but it does so differentially—stretching one arm while compressing the other. By comparing the precise path lengths of the two lasers, LIGO can detect these minute, relative changes, even though the entire apparatus (and its measuring rods) is also stretched.

The question asks how LIGO detects waves if everything stretches. The answer is LIGO's two arms at right angles. If one arm stretches, the other does not stretch in the same way, allowing for a differential measurement.

While quantum entangled particles instantaneously mirror each other's states regardless of distance, this phenomenon cannot be used for faster-than-light communication. The 'information' is inherent in the entangled state; one cannot actively manipulate one particle to transmit new, arbitrary information to the other after entanglement has occurred.

The host acknowledges the plausibility of entangled particles knowing each other's states even if one enters a black hole, but clarifies that you cannot 'after the fact change that information' to send a message like 'turn left instead of right.'

Time capsules, despite good intentions, are largely ineffective for communicating with future generations. Subsequent generations rarely care about or even remember the existence of previous generations' time capsules, as culture and technology advance rapidly, rendering the contents obsolete or uninteresting.

Neil deGrasse Tyson recounts finding a forgotten World's Fair time capsule under a bench. He also mentions putting a MetroCard and an iPod in a time capsule, both of which are now largely obsolete and unwanted.

If humans were to become extinct, rodents, particularly rats, are a strong candidate to become the dominant species on Earth. Their adaptability, wide distribution, and numerous species (compared to Homo sapiens, which has only one remaining species) make them incredibly resilient. Without human predators or environmental constraints, they could evolve to much larger, even human-like sizes.

Reference to the book 'After Man' which explores post-human evolution. Rodents are one of the most successful branches of life. The size of rats is currently limited by the holes they can hide in from humans; without humans, this constraint is removed, allowing for capybara-like or larger evolution.