The speaker, Michael, discusses the concept of gravity and its effects on matter, including humans. He explains that gravity is a property of mass and is responsible for attracting every atom in our bodies to every other atom in our bodies. However, the gravitational influence is so small compared to the Earth's that we don't feel it.
He then raises the hypothetical scenario of the Sun disappearing. He notes that this is unlikely to happen in our lifetime due to the Sun's expansion, but if it did, it would create a significant impact on Earth. The Sun's gravitational influence would cease 8 minutes and 20 seconds after it disappeared, causing Earth to fly out in a straight line, tangent to wherever it was in its orbit.
Without the Sun, the Earth would lose its source of light and heat, causing significant changes in climate and life. For instance, photosynthesis would stop, affecting all life that relies on it. However, the Earth's own heat would continue to radiate away, leading to a rapid drop in temperature. Despite this, life would continue on Earth, albeit in extreme conditions.
The speaker suggests that lifeforms like extremophiles, which live in extreme environments, would thrive without the Sun. These microbes live in deep-sea vents, where they convert heat and gases into energy. They would continue to live without the Sun, forming a closed loop of energy.
In the long term, the Earth would continue to travel through space, potentially reaching other stars and allowing its still-living extremophiles to proliferate life on Earth again.
1. Gravity is a property of matter, including the Moon, Earth, Jupiter, the Sun, and the human body.
2. If someone you like stands 3/4 of a millimeter away from you, every atom in your body and their body will draw you two together with the same gravitational force that the Sun is exerting on you right now.
3. We don't feel the gravitational force between you and someone you're hugging, or your individual body and the Sun, 150 million kilometers away, because it's essentially insignificant compared to the gravitational influence of the Earth.
4. The Sun will not simply disappear, as matter and energy don't vanish. Quantum tunneling could occur, but it would take an incredibly long time for such a probability to be worth discussing.
5. If the Sun disappeared, we would have no idea for a little over 8 minutes and 20 seconds after it disappeared due to the time it takes light from the Sun to reach Earth.
6. The Sun's gravitational grasp on our planet would also take 8 minutes and 20 seconds to end because gravity waves propagate at the speed of light.
7. With no moonlight or sunlight, the universe itself would be our only source of visible light from space.
8. In 2004, Abdul Ahad calculated that the Milky Way contributes about as much light as 1/300th of a full Moon. So there would be enough light from space for us to see around a bit.
9. Photosynthesis would stop immediately if the Sun disappeared, as 99.9% of the natural productivity on Earth is done by photosynthesis, which requires the Sun.
10. Without the Sun, plants would no longer be able to inhale carbon dioxide and exhale life-sustaining oxygen.
11. Without the Sun to add energy, the Earth would radiate away heat exponentially, meaning it would go fast at first and then happen more and more slowly. By the end of the first week without the Sun, the average surface temperature across Earth would be freezing.
12. By the end of the first year without the Sun, the average global surface temperature would be -73 degrees Celsius, -100 Fahrenheit.
13. The best option would be to move to geothermal areas like Yellowstone or Iceland, which would be the few safe havens for human life after the Sun.
14. In the next 10 or 20 years, things would start to get wet with dew, but not with glorious water droplets. Instead, droplets of liquid air would form.
15. In Fritz Leiber's famous science-fiction short story "A Pail of Air," this has already happened.
16. A year or so after the sun disappeared, Earth's oceans will have frozen over. Ice all the way across. But ice is less dense than liquid water, which means that ice floats. And ice is a pretty decent insulator.
17. Instead of becoming frozen and lifeless, extremophiles, like microbes, that live around hydrothermal vents deep in the ocean, would be fine. They live deep in the ocean, far below the point where sunlight can penetrate, and they make energy not through photosynthesis, but via chemosynthesis - converting heat and methane and sulphur into the energy they need.
18. It's amazing to think that life, here on Earth, all alone, flying through space with no Sun, would kind of be fine. Far from becoming a frozen dead rock, or a boring dormant seed, the Earth would be a spaceship, carrying living passengers with enough geothermal heat for billions of years of life.
19. If the Sun disappeared, spaceship Earth would fly out in a straight line covering about 30 kilometers every single second. After just 1 billion years, it will have covered 900 quadrillion kilometers or about 100,000 lightyears - a trip that could potentially take it all the way across our galaxy, near thousands of stars.
20. And nothing's to say it couldn't fall into orbit around one, thaw out, and allow its still-living extremophiles to proliferate life on Earth all over again; maybe one day developing life intelligent enough to uncover whatever is left of our lives.