Why You’d Never Reach A Neutron Star’s Surface — Transcript

Full transcript

1. 0:00You are a million kilometers out and the
2. 0:02thing you have come to land on does not
3. 0:04look like a destination. It looks like a
4. 0:06rounding error. 20 kilometers across, a
5. 0:09city if you are being generous. You
6. 0:12could walk the diameter of it in an
7. 0:13afternoon assuming walking were still a
8. 0:16concept that applied here. Your ship is
9. 0:18calling it a star. You decide for the
10. 0:21moment to trust your ship. The first
11. 0:23thing that goes wrong is not dramatic.
12. 0:25It is arithmetic. You ask the navigation
13. 0:28system for a gentle landing burn, the
14. 0:30kind you would use to settle onto an
15. 0:31asteroid and the number it hands back is
16. 0:34wrong by a factor you have to read
17. 0:35twice. It is asking for more fuel than
18. 0:38exists. Not more than you are carrying,
19. 0:41more than exists. That is your first
20. 0:43honest piece of information about where
21. 0:45you are. This object is the size of a
22. 0:47city and it weighs more than the sun.
23. 0:49Somebody took an entire star, deleted
24. 0:52everything that made it large, and kept
25. 0:54only the part that pulls. So you try the
26. 0:56sensible thing instead. Do not land,
27. 0:59orbit. Come in close, go around a few
28. 1:01times, take some readings, feel clever.
29. 1:04The orbit is possible. It is just not an
30. 1:07orbit in any sense you would recognize.
31. 1:09Close in, a circular orbit around an
32. 1:11object this dense takes on the order of
33. 1:13a millisecond. Not a day, not an hour, a
34. 1:17fraction of a heartbeat. Your ship would
35. 1:20have to whip around the entire star, all
36. 1:2220 kilometers of it, faster than you can
37. 1:24notice a thought arriving and the
38. 1:26sideways speed required to stay up there
39. 1:28is a serious fraction of the speed of
40. 1:30light. There is no cruising past for a
41. 1:32look. There is only falling at a speed
42. 1:35that gets worse the longer you are
43. 1:36honest about it. So you keep falling
44. 1:38toward it because at this point falling
45. 1:40is not a decision you are still making.
46. 1:42At a few hundred thousand kilometers the
47. 1:44view begins lying to you. The star is a
48. 1:47small dark disk with a hard edge and
49. 1:49around that edge sits a ring of light
50. 1:51that has no business being there. You
51. 1:52are seeing the back of the object. Its
52. 1:54gravity is bending light from behind it
53. 1:57and folding it around the sides into
54. 1:58your eyes.
55. 2:00You are looking at something and looking
56. 2:01around it at the same time. Nothing you
57. 2:03have ever seen has prepared you for an
58. 2:05object generous enough to show you its
59. 2:07far side for free.
60. 2:08Then you notice the flicker. The star is
61. 2:10spinning.
62. 2:11Many neutron stars turn several times a
63. 2:14second, and some turn hundreds of times
64. 2:16a second, which means the radiation
65. 2:18streaming off its magnetic poles sweeps
66. 2:20past you like a lighthouse operated by
67. 2:22something in a hurry. Your instruments
68. 2:24log it as a pulse. Your eyes log it as a
69. 2:27strobe you cannot blink away.
70. 2:29This is also, roughly, where you die.
71. 2:32Not from the gravity. From the light.
72. 2:34Neutron stars are typically hot enough
73. 2:36to glow in x-rays rather than in
74. 2:38anything you would call visible. And if
75. 2:40this one is pulling gas off a companion,
76. 2:42or is young enough to still be cooling
77. 2:44from its birth, the space around it is
78. 2:46not empty darkness. It is a furnace with
79. 2:49no walls. Long before you are close
80. 2:51enough to think about landing gear, the
81. 2:53radiation arriving at your hull is doing
82. 2:55to your cells what a welding arc does to
83. 2:57a photograph. So, let us agree to cheat.
84. 3:00Let us say the ship holds, and you hold,
85. 3:02and we keep going, because the genuinely
86. 3:05strange part has not started yet.
87. 3:08At tens of thousands of kilometers, your
88. 3:10electronics begin behaving like
89. 3:11superstitious animals.
90. 3:13Neutron stars carry magnetic fields that
91. 3:15are not merely strong, they are a
92. 3:17different category of thing. A hospital
93. 3:20scanner runs a few Tesla.
94. 3:22A neutron star can run 100 million Tesla
95. 3:24or more, and the rare ones we call
96. 3:25magnetars can run far higher than that.
97. 3:28As you close in, the field climbs, and
98. 3:30at a certain point it stops interfering
99. 3:32with your equipment, and starts
100. 3:33interfering with the equipment you are
101. 3:34made of.
102. 3:36Very strong magnetic fields do not
103. 3:38simply push on atoms, they reshape them.
104. 3:40Squeeze the field high enough, and the
105. 3:42electron clouds around every nucleus get
106. 3:44pulled into long, thin needles, all
107. 3:46pointing the same way, like iron filings
108. 3:49that have given up on having opinions.
109. 3:51Chemistry depends on the shape of those
110. 3:53clouds. Every bond in your body, every
111. 3:55protein, every molecule of water exists
112. 3:58because electrons sit in particular
113. 4:00arrangements. Change the arrangement and
114. 4:03you have not injured the chemistry. You
115. 4:05have canceled it. There is no sensation
116. 4:07attached to this.
117. 4:09There is no moment where you feel your
118. 4:10molecules being edited. There is a
119. 4:12boundary somewhere out in the dark where
120. 4:14the substance formerly known as you
121. 4:16stops being able to hold a chemical bond
122. 4:18together. And you cross it at several
123. 4:20hundred kilometers per second and the
124. 4:22crossing takes no time at all.
125. 4:25We agreed to cheat, so we continue.
126. 4:27Now you start to feel the gravity and
127. 4:29the way you feel it is the part nobody
128. 4:31warns you about. Gravity gets weaker
129. 4:33with distance. On Earth, this is a
130. 4:35technicality because your head and your
131. 4:37feet are close enough together that the
132. 4:39difference between them is nothing. Near
133. 4:41a neutron star, the difference between
134. 4:43them is the whole story. Your feet are
135. 4:45nearer. Your feet are pulled harder.
136. 4:47Your head is pulled less.
137. 4:49And the gap between those two numbers
138. 4:50grows faster and faster as you close in.
139. 4:53It begins as a stretch in your spine,
140. 4:55the sort of pull you might blame on a
141. 4:57long day. Then it becomes a sensation of
142. 4:59hanging as though something has taken
143. 5:01hold of your ankles.
144. 5:02Then it becomes pressure because while
145. 5:04the star is pulling you longer, it is
146. 5:06also pulling you narrower, squeezing
147. 5:08your shoulders inward as every part of
148. 5:10you tries to fall along its own straight
149. 5:11line toward the same single point.
150. 5:14You are being stretched and compressed
151. 5:15by the same force at the same time.
152. 5:17There is no posture that helps.
153. 5:20If you're enjoying this video, please
154. 5:21hit the subscribe button. It genuinely
155. 5:23helps keep the channel alive. Somewhere
156. 5:26in the last few thousand kilometers, the
157. 5:28stretching stops being uncomfortable and
158. 5:30starts being structural. Bone has a
159. 5:32breaking point. Tissue has a breaking
160. 5:34point.
161. 5:35The difference in pull between one end
162. 5:37of you and the other climbs past both of
163. 5:39them and you come apart lengthwise, not
164. 5:42as an injury, but as a consequence of
165. 5:43geometry.
166. 5:45What continues the journey is a thin
167. 5:47column of what you used to be, falling
168. 5:49headfirst, getting longer and thinner
169. 5:51the closer it gets, because the
170. 5:53stretching never stops improving.
171. 5:56Meanwhile, you are picking up speed in a
172. 5:57way that should worry you more than it
173. 5:59does. Falling toward Earth from far
174. 6:01away, you would arrive at about 11 km
175. 6:04per second. Falling toward this object
176. 6:07from far away, you arrive at a
177. 6:08substantial fraction of the speed of
178. 6:10light. The escape velocity at the
179. 6:12surface of a neutron star can be roughly
180. 6:14half of light speed, which means the
181. 6:16impact speed of anything that falls
182. 6:18freely from a great distance is in the
183. 6:20same appalling neighborhood. You are no
184. 6:22longer traveling at a speed. You are
185. 6:24traveling at a percentage.
186. 6:26And as you fall, time itself goes soft.
187. 6:29Gravity this deep slows clocks
188. 6:31measurably. The closer you get, the
189. 6:33slower your remaining seconds run
190. 6:34compared with everyone watching from a
191. 6:36safe distance. From your point of view,
192. 6:39nothing is wrong and everything is
193. 6:40quick. From theirs, your fall is
194. 6:42dragging, your signal is stretching, the
195. 6:45light coming off you is sliding redder
196. 6:46and dimmer as it climbs out of the
197. 6:48gravity well, and you are taking longer
198. 6:50and longer to arrive at a place they can
199. 6:52see perfectly well. Now, finally, the
200. 6:55surface.
201. 6:56It is not what you were imagining. You
202. 6:58may have pictured something molten, or
203. 7:00something gaseous, or something so
204. 7:02exotic that your eyes would refuse it.
205. 7:04What is actually under you is a crust, a
206. 7:07solid one, mostly iron nuclei packed
207. 7:10into a lattice, compressed so tightly
208. 7:12that the strongest steel you have ever
209. 7:13seen would count as a gas by comparison.
210. 7:16Estimates put it many orders of
211. 7:18magnitude stronger than anything in an
212. 7:20engineer's catalog.
213. 7:21It is also extremely smooth. Gravity
214. 7:24here is somewhere around a hundred
215. 7:25billion times what you grew up under,
216. 7:27and gravity that strong does not
217. 7:29tolerate scenery. Anything that tries to
218. 7:31stand up gets flattened.
219. 7:33The tallest mountains on a neutron star
220. 7:35are thought to be millimeters high. You
221. 7:37are approaching the most perfectly
222. 7:38polished object in the universe, and it
223. 7:40is glowing, and you cannot appreciate
224. 7:42either fact because you are a filament
225. 7:44of X matter arriving at a fraction of
226. 7:46light speed and it is not holding still
227. 7:48for you.
228. 7:49Remember the flicker you saw from a
229. 7:51million kilometers out? That was this
230. 7:53surface turning. If this star rotates a
231. 7:55few hundred times a second, the ground
232. 7:57directly beneath you is sliding sideways
233. 7:59at a speed that makes your vertical fall
234. 8:01look leisurely and the equator is moving
235. 8:03fast enough that a noticeable fraction
236. 8:05of light speed is involved.
237. 8:07You are not descending onto a landing
238. 8:08site. You are descending onto a belt
239. 8:10sander the size of a city running at a
240. 8:12speed with no useful comparison and you
241. 8:15are arriving from above at an angle
242. 8:16nobody planned.
243. 8:18There is no landing. There was never
244. 8:20going to be a landing. Landing requires
245. 8:22slowing down and slowing down here would
246. 8:25require an engine capable of fighting a
247. 8:27star.
248. 8:28What happens instead is a conversion.
249. 8:31Everything you had, the mass of your
250. 8:32body and the mass of the ship and the
251. 8:34fuel you never got to use, arrives at
252. 8:36once and stops at once and the energy of
253. 8:39that arrival comes out as a flash of
254. 8:41radiation. A human-sized object hitting
255. 8:43a neutron star releases energy in the
256. 8:45range of the largest nuclear weapons
257. 8:47ever built. Not because you were
258. 8:49carrying anything dangerous, because
259. 8:51falling in a place like this is itself a
260. 8:54weapon. The star does not notice. It has
261. 8:57eaten entire companion stars one spiral
262. 8:59at a time. You are a rounding error
263. 9:02arriving at a rounding error's speed.
264. 9:04What is left of you is now part of the
265. 9:06crust, not buried in it, spread across
266. 9:09it. Your atoms are pressed into a layer
267. 9:11thought to be no thicker than a single
268. 9:12atom, smeared flat over a surface that
269. 9:15will not permit anything taller and at
270. 9:17those pressures the atoms themselves
271. 9:18stop being iron or carbon or calcium.
272. 9:21Electrons get crushed into nuclei.
273. 9:24Nuclei crowd together until the
274. 9:25distinction between them stops meaning
275. 9:27much. You are not dead in the ordinary
276. 9:29sense, which usually leaves behind a
277. 9:31body. You have been resolved back into
278. 9:33stock ingredients.
279. 9:35And here is the quiet, genuinely strange
280. 9:37ending. Far away, to anyone still
281. 9:40watching, you never quite arrive. Your
282. 9:42final light crawls up out of the gravity
283. 9:44well, stretching and dimming as it
284. 9:46climbs, redder every second, fainter
285. 9:49every second, until it drops below
286. 9:51anything an instrument can register.
287. 9:53You are not seen to hit, you are seen to
288. 9:55fade.
289. 9:56They get a slow, silent, reddening
290. 9:58smudge that goes dark.
291. 10:00You got a trip of less than a second,
292. 10:02most of which you were in no condition
293. 10:04to attend.
294. 10:05Somewhere out there, the star keeps
295. 10:07spinning, keeps pulsing, keeps sweeping
296. 10:09its beam across the dark on a schedule
297. 10:11accurate enough to rival an atomic
298. 10:13clock, entirely unchanged by the fact
299. 10:15that you tried.
300. 10:17The honest summary is this: You cannot
301. 10:19land on a neutron star for the same
302. 10:21reason you cannot shake hands with a
303. 10:22lightning bolt.
304. 10:24There is no version of the encounter in
305. 10:25which you remain a thing that has a
306. 10:27shape. The only survivable way to visit
307. 10:29one is exactly the way we already do it,
308. 10:32from a very long way off, watching the
309. 10:34light, doing the arithmetic, and being
310. 10:36extremely glad about the distance.