How fast are you moving right now? - Tucker Hiatt
你現在時速多少? - Tucker Hiatt
1,917,539 views ・ 2014-01-27
請雙擊下方英文字幕播放視頻。
譯者: 紀維 秦
審譯者: Michelle CHOU
00:08
How fast are you moving right now?
0
8996
3255
「現在你的時速多快?」
00:12
That seems like an easy question.
1
12251
1582
你以為這問題很單純吧。
00:13
The first tempting answer is,
2
13833
1367
對於使用個人電腦看影片的你,
首先閃過的念頭應該是:
00:15
"I'm not moving."
3
15200
1668
我沒移動啊。(除非你在通勤中)
00:16
Upon further reflection,
4
16868
1305
更細深思,
00:18
you realize that maybe the Earth's motion counts.
5
18173
2860
你意會到,說不定
地球的運轉也得考慮進來。
00:21
So, a second tempting answer is,
6
21033
2086
因此,再試一次你答道:
00:23
"19 miles/second around the Sun."
7
23119
2685
平均每秒 29.79 公里繞著太陽轉,對吧
(一月地球通過近日點,高於均速。
七月遠日點則相反)
00:25
But then you recall learning that the Sun
8
25804
1877
但不想則已,一想你又發覺太陽
00:27
moves around the center of the Milky Way galaxy,
9
27681
2838
正繞著銀河系中心運轉,
00:30
and the Milky Way moves within the Local Group of galaxies,
10
30519
3463
而銀河系正在本星系群中運轉,
00:33
and the Local Group moves within the Virgo Cluster,
11
33982
2832
本星系群又是室女座星系團的一部分,
00:36
and the Virgo Cluster moves within...
12
36814
2419
室女座星系團又是室女座超星系團......
00:39
"How fast are you moving?"
13
39233
1336
於是「你正以多快速度運動?」
00:40
is not an easy question.
14
40569
1585
不是個好回答的問題。
00:42
When Mission Control tells astronauts
15
42154
1710
當太空任務控制中心告訴太空人
00:43
how fast they're going,
16
43864
1376
他們火箭的飛行時速
00:45
there's always an assumed standard of rest.
17
45240
3087
總有個默認的「靜止」參考點。
00:48
At the start of the voyage,
18
48327
1086
在發射之初,
00:49
speeds are given relative to the launchpad.
19
49413
2369
火箭速度根據的基準點是發射平台。
00:51
But later, when the launchpad is
20
51782
1583
然而不久之後,
00:53
just one more arbritrary place
21
53365
1501
發射平台就退居
地球快速運轉的表面上
00:54
down there on Earth's spinning surface,
22
54866
2055
一個無關緊要的地點,此時
00:56
speeds are given relative to
23
56921
1697
飛行速度的參考基準點是一個
00:58
the idealized, non-spinning pinpoint center of Earth.
24
58618
4723
理想化的:地球本體的旋轉、質量中心。
01:03
On their way to the Moon,
25
63341
1128
在登月任務中,
01:04
Apollo astronauts had a hard time
26
64469
1955
阿波羅太空人瞭解到
01:06
answering the question,
27
66424
1168
即使問題簡單如
「你們現在飛行得多快?」
01:07
"How fast are you moving?"
28
67592
2049
都很難回答。
01:09
Speed away from Earth was one thing,
29
69641
2200
遠離地球的速度是一回事,
01:11
and speed toward the Moon was quite another.
30
71841
2665
朝向月球的速度
並不見得與前者相同。
01:14
That's because the Earth and the Moon
31
74506
1501
理由是地球與月球
事實上是互相繞轉的系統
01:16
move relative to one another.
32
76007
2058
(地月系統的質量,也是旋轉中心位在地球當中,但距離地心長達地球半徑的3/4,也就是地月的花式溜冰中地球也會相對於此中心搖擺。另外,太陽對月球的引力事實上比地球對月球大兩倍。想想看為何月球沒被太陽吸走。)
01:18
Ah, of course!
33
78065
1409
啊,你恍然大悟。
01:19
Speed is a relative quantity.
34
79474
2213
這影片想要彈
「速度是相對概念」這老調,對吧?
01:21
When Captain Kirk ask Lieutenant Sulu
35
81687
2996
當《星艦迷航記》的寇克鑑長對蘇魯上尉提問
(注:星艦當用海空軍軍階)
01:24
if the Starship Enterprise has reached a speed of warp 7,
36
84683
3156
「星艦企業號是否已達曲速因子7 」
(Star Trek的科幻空想單位,
對應幾倍光速設定很亂,
總之皆為超光速)
01:27
Sulu should reply,
37
87839
1570
假如蘇魯是物理魂,應該回答:
01:29
"Relative to what, Captain?"
38
89409
1836
「艦長,你問多快是相對於什麼?」
01:31
Such a sassy reply
39
91245
1504
即使如此有性格的答案
01:32
may get subordinate Starfleet officers in trouble,
40
92749
2375
八成會讓這位艦隊部屬惹上麻煩,
01:35
but it is the only good answer
41
95124
1792
這卻是唯一有格調的答案,
01:36
to the question, "How fast are you moving?"
42
96916
2464
因為「現在多快?」本身條件並不充足。
01:39
This is basic relatively talking.
43
99380
1876
這是基本的相對性思考。
01:41
Not fancy Einsteinian relativity,
44
101256
2544
不是愛因斯坦那種高級的相對性,
01:43
but good old fashioned (and still correct)
45
103800
2341
而是老忠實,仍然可靠的
01:46
Galilean relativity.
46
106141
2085
加利略式的相對性(運動相對性)
01:48
Galileo seems to have been the first person
47
108226
1996
加利略大概是史上第一人做出
01:50
to realize that there is no such thing
48
110222
1784
「世上無絕對的速度」的洞見
01:52
as an absolute speed.
49
112006
2055
「世上無絕對的速度」的洞見
01:54
Speeds are relative.
50
114061
2250
速度,如前所述,皆相對
01:56
This means that speeds only have meaning
51
116311
2156
亦即在沒有給予參考系
(reference frame)之下
01:58
when they are referred to a reference frame.
52
118467
2976
速度是無法定義的。
02:01
Presumably that reference frame is itself at rest.
53
121443
3990
一開始你似乎能假定這個參考點靜止。
02:05
But then we have to ask again,
54
125433
1932
然而追究起來,
02:07
"At rest relative to what?"
55
127365
2002
「你說靜止是對於什麼靜止?」
(這裡忘了提,沒有絕對速度也代表
沒有絕對空間、或者絕對座標)
02:09
Because even the concept of rest
56
129367
1752
因為,即使靜止(也就是速度為零)
02:11
has lost any hint of absolute meaning.
57
131119
2917
也是速度,因此
也不能獨立於系統定義出來。
02:14
Speed is relative, and rest is relative.
58
134036
2804
速度是相對的,靜止也是相對的。
02:16
Earth's speed is 19 miles/second relative to the Sun.
59
136840
4555
地球的每秒29.79公里是相對於太陽。
02:21
The Enterprise's speed is warp 7
60
141395
2111
企業號的曲速 7
02:23
relative to the center of the Milky Way galaxy.
61
143506
2963
是相對於銀河系中心。
02:26
Your speed is zero relative to your easy chair.
62
146469
3946
你的速度是零,相對於你的椅子。
02:30
But depending on where you sit,
63
150415
1603
但取決於你所在地的緯度,
02:32
it is hundreds of miles/hour relative to Earth's center.
64
152018
3904
你與地心的相對速度可以介於每秒 463 公尺,和 0 公尺之間(各強國的衛星發射站首選低緯地區,為什麼?)
02:35
When we furrow a brow and ask,
65
155922
1667
當我們皺眉尋思:
02:37
"But how fast is Earth really moving?"
66
157589
2224
「那地球本身究竟是以什麼速度移動呢?」
02:39
we imagine Spaceship Earth
67
159813
2045
我們想像中的宇宙太空船「地球號」
02:41
plowing through the ocean of space
68
161858
1625
正在宇宙廣袤的空間中一面破浪而進
02:43
as it orbits the Sun.
69
163483
1795
一面繞行太陽。
02:45
But space is not an ocean.
70
165278
1581
但空間可不是海洋,
02:46
It has no substance as water does.
71
166859
2297
空間不存在水那樣靜止的介質(沒有以太)
02:49
Space is not a thing;
72
169156
2295
空間本身不是物質
(Michelson-Morley 實驗說明以太不存在)
02:51
space is nothing.
73
171451
2376
空間什麼都沒有。
02:53
Space is no thing.
74
173827
1502
空間是空無一物。
02:55
You can move between two points in space,
75
175329
2176
你從空間中的一點運動到另一點,
02:57
say between Earth and Mars,
76
177505
1703
例如從地球到火星,
02:59
but you can't move through space.
77
179208
2253
然而實際上你不能「穿過空間」,
03:01
There's nothing to move through.
78
181461
1550
空間就像影子一樣無物可穿。
03:03
It's like trying to say how much a hole weighs.
79
183011
2587
就好像問「洞有多重」一樣。
(譯:倘若 Vsauce 有這標題的影片我也不會驚訝XD)
03:05
A hole weighs exactly nothing
80
185598
2491
洞的重量什麼的根本沒有,
03:08
because a hole is nothing.
81
188089
1916
因為洞是一個概念,不是實體。
03:10
It's a void, and so is space.
82
190005
2541
洞只是「空無一物」的概念,而空間也一樣。
03:12
To move relative to nothing is meaningless.
83
192546
3178
相對於「什麼都沒有」而動,
不是什麼有用的概念。
03:15
The concepts of speed and of rest
84
195724
2616
速度,或靜止,如同加利略的灼見
03:18
have only relative meaning.
85
198340
1623
天生就得有外在的參考物,
一個巴掌拍不響。
03:19
They are absolutely meaningless.
86
199963
1893
宇宙也不懂你說的速度是怎麼一回事。
03:21
They mean something
87
201856
1656
因為速度總是附帶著隱藏前提,
03:23
only with respect to arbitrarily chosen,
88
203512
1932
一個自由設置
03:25
artificial frames of reference.
89
205444
2746
全然是人為概念的參考框架(參考系)。
03:28
If, someday, you are buckled into your spaceship,
90
208190
2463
設想,有一天,你在
你的太空座椅上繫著安全帶
03:30
and you see from the side window, say,
91
210653
2046
望向窗外看到,舉例而言,
03:32
a space station whizz by at constant speed,
92
212699
2956
一個等速移動的太空站,
03:35
there is no way to know which of you is really moving.
93
215655
2888
你和對方,在荒涼的宇宙中沒有任何實驗能證明誰真的在動,或者兩者都在動。
03:38
Neither of you is really moving
94
218543
1748
又,某種程度來說你們的移動都沒有意義
03:40
because there is no deep reality about constant speed.
95
220291
2563
因為等速本身的實在性完全無法確認,
03:42
Constant speed in a straight line
96
222854
2170
等速運動永遠有可能只是種表象
03:45
has only relative meaning,
97
225024
1898
永遠需要藉由外在現象而定義
(注:這傢伙台詞文采差,還跳針,翻譯火大)
03:46
a kind of relative reality.
98
226922
2253
某種相對現實。
03:49
Does this mean that all motion is relative?
99
229175
2420
所以,你已被我說服
「所有運動都是相對」了嗎?
(是啊,感謝你的洗腦)
03:51
No! Some motions have only relative meaning,
100
231595
3170
哈,事情不是憨人所想得那麼簡單。
有些動作只有純粹相對下的意義,
03:54
but some motions have absolute meaning,
101
234765
2142
然而確實存在絕對意義的運動
(感謝你的拖拖拉拉現在才說)
03:56
are absolutely real.
102
236907
2112
擁有非常真實的效應。
03:59
For example, constant speed is relative,
103
239019
3257
簡言之,常速是相對的,
04:02
but change in speed is absolute.
104
242276
2415
但【加速度是絕對的】。
04:04
Calling something absolute in science
105
244691
2101
科學上,說某物是絕對的,
04:06
means that arbitrary standards are not used
106
246792
2989
代表測量的基準
04:09
in its measurement.
107
249781
1166
無法任意選擇。
04:10
It is unambiguously measurable.
108
250947
2168
而且對於實驗觀測只有唯一解讀方式。
04:13
When your spaceship fires its engines,
109
253115
2289
當你的太空船引擎點火,
04:15
your change in speed is beyond doubt.
110
255404
2998
加速度的效應無庸置疑,
你會被 G 力壓到椅子裡。
04:18
You feel it in your stomach,
111
258402
1470
連你的內臟都測量得到,
04:19
and your ship's sensors can measure it.
112
259872
2100
當然,飛船上的力學儀器也能輕鬆分辨。
04:21
Outside your window,
113
261972
1278
看出你的窗口,
04:23
the passing space station
114
263250
1053
現在太空站與你的相對速度,
04:24
may seem to be changing speed,
115
264303
1952
似乎也在改變加速,
04:26
but the beings inside the station will not feel it.
116
266255
2750
然而在太空站裡的人
會繼續飄浮毫無感覺,
04:29
And no sensors can measure it.
117
269005
1666
並且他們的儀器並不會感到加速。
04:30
You are really changing speed,
118
270671
2067
真正的在改變速度的是你,
04:32
and they are really are not.
119
272738
1983
而非你觀察的太空站。
04:34
There's something absolutely real
120
274721
1585
與恆速運動(慣性運動)不同的是,
04:36
about changes in speed.
121
276306
2282
變速運動(加速運動)
是貨真價實測量得到的。
04:38
The same goes for rotation.
122
278588
2001
同樣的理由,旋轉運動也是絕對的。
04:40
If your spaceship is spinning,
123
280589
1583
若你的太空船正在旋轉,
04:42
you can feel it,
124
282172
1000
你絕對感覺得到
04:43
and your ship's sensors can measure it.
125
283172
1558
你飛船的感應器也可以。
(加速座標必有假力,旋轉座標中
是離性力、柯氏力)
04:44
The space station outside
126
284730
1335
在你看來你窗外的太空站,
04:46
may seem to be going around you,
127
286065
1752
也在用與你一樣的角速度旋轉,
04:47
but it is you who feels queasy,
128
287817
1666
但唯一會暈得亂七八糟的是你,
04:49
not the folks in the space station.
129
289483
1878
他們不會(繼續飄浮)。
04:51
You are really spinning,
130
291361
1588
你在轉而對方沒在轉,
04:52
and they really are not.
131
292949
1607
可以透過扎實的實驗分辨出來。
04:54
There's something absolutely real about rotation.
132
294556
2811
旋轉,很神奇的,具有一個獨立的實在性。
04:57
So, some motions are relative, and some are not.
133
297367
2920
總結本集,有純粹相對的運動,
也有純粹絕對的運動。
05:00
There is no deep reality about constant speed,
134
300287
2557
慣性/恆速運動永遠不能
以實驗確定為實在,
總是有只是表象的可能
05:02
but changes in speed are deeply real,
135
302844
2866
但加速度本身是實在的,
05:05
and so are rotations.
136
305710
1380
旋轉也是。
05:07
We have to be thoughtful
137
307090
1164
在平凡的日常經驗中,
05:08
in our analysis of everyday experience
138
308254
1501
你得要萬分謹慎,並且「想太多」
05:09
in order to identify what is deeply real.
139
309755
2667
才能分辨實在與否。
05:12
Since we can be fooled by perceptions
140
312422
2223
因為即使簡單如速度的概念
05:14
as basic as speed,
141
314645
1361
都會為我們的感官所混淆,
05:16
maybe every perception deserves careful scrutiny.
142
316006
2583
那或許所有感覺都值得審慎檢驗。
05:18
This is what inspired Einstein
143
318589
1948
這個思想實驗啟發了愛因斯坦
05:20
to his incredible insights
144
320537
1412
去寫下不朽的真知灼見
05:21
about the speed of light and forward time travel.
145
321949
2329
關於光速,與加速座標系的時間膨脹
--向未來的時間旅行。
05:24
Knowing how to identify
146
324278
1701
對於鑑別各種
05:25
what is deeply real
147
325979
1586
「究竟真實」
05:27
is tough and important work.
148
327565
2626
是重要而艱難的工作。
05:30
If a police officer ever pulls you over for speeding
149
330191
3131
下次若被警察路邊攔檢,說,
05:33
and asks, "Do you know how fast you were going?"
150
333322
2536
「這位先生,你知道剛才你開多快嗎?」
05:35
an insightful, though perhaps unwise, reply
151
335858
3414
你可以報以一個深刻,也許有點不智,的回答:
05:39
would be, "Relative to what?"
152
339272
2503
「那要看相對於什麼而言啊。」
05:41
And then, as you sit in the backseat of the police car
153
341775
2724
於是乎,你就可以在警車的後座
05:44
and feel it accelerate toward jail,
154
344499
1859
感受那朝向拘留所的加速度,
05:46
you can add,
155
346358
1836
並且補充說
05:48
"But some things are absolute!"
156
348194
4000
「啊,但還是有些運動是絕對的啊。」
New videos
關於本網站
本網站將向您介紹對學習英語有用的 YouTube 視頻。 您將看到來自世界各地的一流教師教授的英語課程。 雙擊每個視頻頁面上顯示的英文字幕,從那裡播放視頻。 字幕與視頻播放同步滾動。 如果您有任何意見或要求,請使用此聯繫表與我們聯繫。