What If The Sun Disappeared? — Transcript

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1. 0:00Hey, Vsauce. Michael here.
2. 0:02Gravity is a property of matter, anything with mass. This includes the Moon, Earth,
3. 0:10Jupiter, the Sun, and even you - your body. In fact, if you kinda like somebody, have
4. 0:19them stand 3/4 of a millimeter away from you. At that distance, cumulatively, every atom
5. 0:27in your body and every atom in their body will draw you two together with the same gravitational
6. 0:33force that the Sun is exerting on you right now.
7. 0:38Of course, we don't feel either of those forces because compared to the gravitational influence
8. 0:44of the Earth, they are basically nothing. You don't need to concern yourself with the gravitational
9. 0:49attraction between you and someone you're hugging, or, your individual body and the
10. 0:55Sun, 150 million kilometres away. In fact, the Sun may as well not exist.
11. 1:02What if the Sun disappeared?
12. 1:06Well, to be sure, it's not going to happen. The Sun will die billions of years from now
13. 1:11by expanding, boiling off our oceans and swallowing the Earth whole.
14. 1:15The Sun is not going to simply disappear. Matter and energy don't vanish. Of course,
15. 1:22matter can quantum tunnel to different locations, but on the scale of the Sun there is not
16. 1:28enough time in the lifetime of millions and billions of universes for such a probability
17. 1:33to even be worth discussing.
18. 1:35But let's discuss it anyway, as a thought experiment to determine how the Earth would
19. 1:41get along with no Sun. What will the Earth do and what can it do alone?
20. 1:49At the exact moment that the Sun disappeared, we would have no idea. Because it takes light
21. 1:55from the Sun 8 minutes and 20 seconds to reach Earth. So, for a little over 8 minutes
22. 2:01after the Sun disappeared, we would have no idea. Once we did, confusion and mass panic
23. 2:08would, most likely, ensue.
24. 2:10The Sun's gravitational grasp on our planet would also take 8 minutes and 20 seconds to
25. 2:15end. This is because gravity waves propagate at the speed of light. So, the very moment
26. 2:21we saw our Sun disappear, we would also lose its gravitational influence and Earth would
27. 2:27fly out in a straight line, tangent to wherever it was in its orbit.
28. 2:33The finite speed of light and gravity mean that as panic and fear spread across the Earth
29. 2:39at the loss of our Sun, we could still, for a while, look up into the sky and see our planetary
30. 2:45buddies, further out, continuing to operate as if nothing had happened.
31. 2:50For instance, Jupiter would continue orbiting and reflecting light from a Sun that no longer
32. 2:56existed for about 30 minutes after the Earth already knew the Sun was gone. And, depending
33. 3:02on where Jupiter was in its orbit, it would take another 30 minutes to an hour for us
34. 3:06to watch the reflected light of Jupiter snuff out.
35. 3:11With no moonlight or sunlight, the universe itself would be our only source of visible
36. 3:17light from space.
37. 3:18In 2004, Abdul Ahad calculated that the Milky Way contributes about as much light as 1/300th
38. 3:26of a full Moon. So there would be enough light from space for us to see around a bit. But,
39. 3:31of course, electricity and fossil fuels would still be usable for a while. So, cities and
40. 3:37towns could continue to be lit by manmade sources, just like a typical night; except,
41. 3:43it would be night everywhere.
42. 3:46Photosynthesis would stop immediately, and this is huge. I had a great discussion about
43. 3:53this video with Henry from MinutePhysics, and the new channel MinuteEarth. If you're
44. 3:58not subscribed to MinuteEarth, you definitely should be.
45. 4:01In one of his episodes there, he mentions that 99.9% of the natural productivity on
46. 4:08Earth is done by photosynthesis, which requires the Sun. Without the Sun, plants would no
47. 4:15longer be able to inhale carbon dioxide and exhale life-sustaining oxygen.
48. 4:22But, don't worry. Collectively, all of us humans, all 7 billion of us, breathe in about
49. 4:286 trillion kilos of oxygen every year. But our atmosphere contains a whopping quintillion
50. 4:37kilos of oxygen. So, even without photosynthesis, and, including all the other animals, and
51. 4:43insects, and microorganisms that consume oxygen, it would take us thousands of years to run
52. 4:49out.
53. 4:50The poor plants themselves would be much worse off. Without the Sun, most of them would
54. 4:55die within days or weeks. Except for large plants. Giants trees, for instance, contain
55. 5:01enough sugar for energy that they could technically live in the dark for years. Their problem
56. 5:08is going to be that the Earth will get quite cold. In fact, mighty trees would freeze to
57. 5:14death. Their blood, the water and sap inside of them, solidify way before they died of starvation.
58. 5:21Right now, with our Sun, the average surface temperature on Earth, hot places and cold
59. 5:27places, and different seasons all considered, is an arguably comfortable 14 to 15 degrees
60. 5:33Celsius.
61. 5:35Without the Sun to add energy, the Earth would radiate away heat exponentially, meaning
62. 5:40it would go fast at first and then happen more and more slowly. By the end of the first
63. 5:47week without the Sun, the average surface temperature across Earth would be freezing.
64. 5:53Zero Celsius, 32 degrees Fahrenheit. Now, temperature's like this happen all the time
65. 5:58on Earth, we're used to it. Panic and fear and looters and anarchy aside, for the first
66. 6:03few days or months, we could get by.
67. 6:06But by the end of the first year without the Sun, the average global surface temperature
68. 6:13would be -73 degrees Celsius, -100 Fahrenheit.
69. 6:18The best option, really, would be to move to geothermal areas like Yellowstone or Iceland.
70. 6:24These places would be the few safe havens for human life after the Sun. Nearly all life
71. 6:31on Earth exists because of, and is dependent upon, extraterrestrial energy: the Sun. But
72. 6:39the Earth produces its own heat. Despite floating in the coldness of space for billions of years,
73. 6:46down below the crust the Earth is quite warm.
74. 6:4920% of this warmth came from the fact that when the Earth formed, mass crushed so tightly
75. 6:55in the middle that the pressure liquified rock. The other 80% of Earth's internal heat
76. 7:01comes from that fact that deep in its core, radioactive elements decay, providing the
77. 7:06energy needed to keep the Earth's core at 5,000 degrees Celsius.
78. 7:11Anyone who failed to secure a position within one of these bastions of warmth, or, perhaps,
79. 7:16underground in a community warmed and powered by nuclear fuel, would likely be dead within
80. 7:22the first year of no Sun.
81. 7:25In the next 10 or 20 years things would start to get wet with dew. But not with glorious
82. 7:33water droplets. Instead, droplets of liquid air. The air would literally become cold enough
83. 7:40for the gasses that make it up to condense, or form clouds and precipitate, first as rain,
84. 7:47and then as it got colder and colder, eventually, as snow.
85. 7:51In Fritz Leiber's famous science-fiction short story "A Pail of Air," this has already happened.
86. 7:58The Earth was ripped away from the Sun, and, in order to survive, a family must go outdoors
87. 8:03in a special suit and scoop up a pale of just the oxygen snow, bring it back in, and place
88. 8:09it over a fire to warm and allow them to breathe.
89. 8:14A year or so after the sun disappeared, Earth's oceans will have frozen over. Ice all the
90. 8:20way across. But ice is less dense than liquid water, which means that ice floats. And ice
91. 8:28is a pretty decent insulator. So, for billions of years after the Sun disappeared, liquid
92. 8:37water could still exist at the bottom of our oceans, protected and insulated from space
93. 8:42by miles of ice above it, and warmed by vents on the ocean floor that spew water out, super
94. 8:49heated by Earth's interior.
95. 8:52This would continue on Earth for a very, very long time - Sun or no Sun. Instead of becoming
96. 9:00frozen and lifeless, extremophiles, like microbes, that live around hydrothermal vents deep in
97. 9:07the ocean, would be fine. They live deep in the ocean, far below the point where sunlight
98. 9:13can penetrate, and they make energy not through photosynthesis, but via chemosynthesis - converting
99. 9:20heat and methane and sulphur into the energy they need. They are then eaten by clams and
100. 9:25tubeworms.
101. 9:26Extremophiles deposit minerals back into the vents, meaning that their food chain is complete.
102. 9:32It's a circle. It's independent of the Sun. Earthlings like them would thrive if the Sun
103. 9:40were to disappear. They would live just fine without every knowing that the Sun was gone.
104. 9:45Or, honestly, without ever even knowing it existed in the first place.
105. 9:51It's amazing to think that life, here on Earth, all alone, flying through space with no Sun,
106. 9:58would kind of be fine. Far from becoming a frozen dead rock, or a boring dormant seed,
107. 10:07the Earth would be a spaceship, carrying living passengers with enough geothermal heat for
108. 10:14billions of years of life.
109. 10:17If the Sun disappeared, spaceship Earth would fly out in a straight line covering about
110. 10:2230 kilometres every single second. After just 1 billion years, it will have covered 900 quadrillion
111. 10:31kilometres or about 100,000 lightyears - a trip that could potentially take it all the way across
112. 10:38our galaxy, near thousands of stars. And nothing's to say it couldn't fall into orbit around one,
113. 10:46thaw out, and allow its still-living extremophiles to proliferate life on Earth all over again;
114. 10:55maybe one day developing life intelligent enough to uncover whatever is left of our
115. 11:01lives. Maybe they could even find this very video.
116. 11:06In which case, hi, uh, you're welcome
117. 11:11for this video about your planet's history and journey.
118. 11:15And, um, as always,
119. 11:19thanks for watching.