تدريب Shadowing: The only good nuclear accident - تعلم التحدث بالإنجليزية عبر الفيديو
جارٍ إنشاء الدرس...
1
Put on your guns.
2
There's something really unusual about this photo from 1955.
3
Can you spot it?
4
It was taken on Fremont Street in Las Vegas.
5
And this glow from the side is the only indication that the photographer had captured the explosion of an atomic bomb.
6
Three, two, one.
7
After World War II, the U .S detonated dozens of test nukes at a site an hour outside Vegas.
8
These weren't little explosions.
9
Many were as large as the blast that killed 140 ,000 people at Hiroshima.
10
On Pacific Islands, they tested the much more powerful hydrogen bombs.
11
But it was the Soviets who dropped the largest nuclear weapon ever tested.
12
Before 1963, above -ground nuclear tests released the explosive power of 25 ,000 Hiroshima bombs, with lasting effects on communities nearby.
13
But the reason we're talking about this today is that those mushroom clouds also created a new scientific tool,
14
one that could reveal whether this painting is a forgery or how long this shark could live, or if selling this ivory figurine was a violation of international law.
15
We are going to dig into this mystery, and you'll see how nukes from the Cold War became a weapon in the fight against the slaughter of elephants.
16
This statue of a poet with a basket of peonies was
17
one of 76 ivory artifacts seized from the home of an antiques dealer in the Czech Republic.
18
He'd told the authorities that he'd inherited the artifacts from his mother and that they were legal to sell.
19
But were they?
20
That depends on exactly how old that ivory was.
21
Ivory comes from the teeth of certain animals, most often the massive upper incisors of the elephant.
22
They grow these tusks for foraging and fighting.
23
But humans realized a long time ago that they also make great art supplies.
24
Ivory is a really beautiful material.
25
It's shiny and smooth and dense.
26
Across different cultures and centuries, ivory has been moved around the world to be carved into art for the elite.
27
And later, to be fed into machines to make products for the middle class too.
28
The tusks took increasingly remote journeys from their source at times carried by people who were enslaved.
29
And by the 1980s, after Japan became the world's top ivory importer, elephant populations were in free fall.
30
So governments got together and banned the international trade in ivory that had been operating for thousands of years, leaving some exceptions for antique artifacts.
31
When the ivory ban happened in 1989, they completely shut down poaching.
32
But it was not very long -lived, maybe three, four years, and then poaching started to creep up again.
33
By one estimate, 144 ,000 African elephants were killed between 2007 and 2014 as demand picked up in China.
34
Poaching has declined some since then, but African elephants are still endangered because people are still buying and selling illegal ivory.
35
And just a quick break to say that this footage came from Storyblocks, which is the sponsor of today's video.
36
We love Storyblocks.
37
Storyblocks is this huge library.
38
It's all available if you have a subscription, so you don't have to pay individually for different clips.
39
And one thing that's happening is that stock libraries are starting to fill up with AI -generated stuff.
40
But Storyblocks recently put out a statement.
41
I want to read it to you because I thought it was really interesting.
42
They said, while we see practical use cases for generative AI video, audio, and images, we do not accept generative content submissions into our library.
43
What a relief.
44
Yeah.
45
For us, when we're trying to make journalistic content and say, look at this thing that's real out in the world, it's nice to know that we can still do that with Storyblocks.
46
Right now, you can get two extra months free when you sign up for their annual plan.
47
Go to storyblocks .com slash howtown to grab that offer before it's gone.
48
Okay, let's get back to this guy.
49
The dealer who was selling it had a report from a specialist in East Asian culture who said
50
that the artifacts came from the first Chinese republic before 1947.
51
That would make them legal to sell under the EU's rules at that time.
52
But a team of researchers in the Czech Republic decided to fact -check that expert with a more objective test,
53
a test that relies entirely on those nuclear bombs from the 50s and 60s.
54
And what was that test?
55
Well, what do you know about carbon -14?
56
I know that carbon, so carbon -12 is the most abundant one.
57
Carbon -14, I believe, has two extra neutrons kind of stuck on there.
58
Is that right?
59
That's right.
60
Carbon -14 is an isotope of carbon, but it comes from nitrogen.
61
Almost 80 % of Earth's atmosphere is composed of nitrogen atoms, which have seven protons and seven neutrons.
62
But if a spare neutron passes close by, a nitrogen nucleus can absorb it, creating an excited form of nitrogen -15,
63
which quickly relaxes by releasing a proton.
64
That turns it into carbon, carbon -14, otherwise known as radiocarbon, which reacts with oxygen to produce a special,
65
limited -edition form of CO2.
66
But all you really need to know is that those spare neutrons
67
that kick off that whole process can come from natural sources, or they can come from nuclear bombs,
68
which completely altered the ratio of carbon 14
69
and carbon 12 in the air i'm curious how much variation
70
it has had sort of naturally compared to the bomb pulse
71
if you look at what has happened in the last 5 000 years we're of the order of few percent
72
but if you compare it with the bomb spike you know the radio carbon concentration doubled between 1955 to 1963
73
so in just eight years which is nothing in the history of our planet, it's very, very...
74
Unmistakable.
75
Yeah, that's for sure, yes.
76
A 1963 treaty required nuclear tests to be done underground, so the concentration of carbon -14 in the air peaked
77
and then declined as the carbon cycle moved the CO2 into the oceans and into plants through photosynthesis.
78
Researchers quickly detected the spike in twigs from Rome, in the milk of cows in Norway, and after a lag of about a year in the blood of New Yorkers.
79
They've been tracking the carbon -14 in the air ever since, and when you compile the data from the past 60 years, we get the radiocarbon bomb curve.
80
This is more than just an odd souvenir from the Cold War
81
because the bomb pulse installed a clock in every living thing.
82
So what year were you born?
83
1987. Okay, so the enamel of your molars, which formed around the time you were born, captured the air around 1987.
84
Right.
85
Part of the lens in our eyes also locks in carbon around birth, so that's another neat archive.
86
A little less accessible, though.
87
Unfortunately, yeah.
88
And then your bones turn over more slowly.
89
So right now your rib reflects the air from about 10 or 20 years ago.
90
and then the carbon in your hair
91
and your nails changed over within the last three years
92
and those keep updating until you die nice
93
if i don't know anything about when you lived
94
but i for some reason have some of your teeth
95
and some of your hair i can put your life on a timeline plus
96
or minus a few years thanks to the bomb pulse i guess you're looking at my corpse in this macabre example.
97
I'm sorry I used you for an example.
98
Yeah, what is this?
99
I should add that radiocarbon takes a slower route from the air through the ocean.
100
So if someone eats mostly seafood, their bodies will contain carbon from an older atmosphere, and you have to adjust for that.
101
You start with physics and then you end up with biology, biochemistry, and mathematics as well.
102
So it's interesting.
103
Most of the nuclear tests were done in the northern hemisphere.
104
But carbon mixes globally in the air after a couple of years.
105
So all of the elephants that have lived since the 1950s have teeth that were time -stamped with the bomb pulse.
106
That makes it a unique tool for tracking the ivory trade.
107
The researchers carefully drilled out a sample from the bottom of the statue and measured the concentration of carbon -14.
108
And they found that it matched the atmospheric level after the start of the nuclear tests, not before.
109
Same with this one, and this one, and this one.
110
In their study of 46 artifacts from multiple seizures, the Czech researchers concluded that nearly 60 % were not legal antiques,
111
contradicting the experts who had said they were.
112
The dealers were convicted and punished for marketing ivory that was harvested after 1947.
113
But the study couldn't tell us exactly how recent that ivory was.
114
That's because the bomb pulse offers two possible dates for a given level of carbon -14, in this case 1962 and 1974.
115
To figure out which one is correct, they would need to drill another hole in the statue.
116
See, an elephant's tusk grows continuously from a cone of tissue at the base called the pulp cavity.
117
So the tip captures carbon that the animal consumed at the beginning of its life, and the base captures the carbon around the time of death.
118
If I can take two samples, one closer to the tip and the other one closer to the base.
119
Then I know that regardless of the age I measure, the sample which is closer to the tip has to be older than the one closer to the base.
120
And so I can exclude all the possible time intervals which do not respect this relative dating.
121
Somehow you have to be clever. So clever.
122
You could also compare the ivory at the center of a tusk to the outer layers which are older.
123
That's what they did in this study of raw ivory that had been seized by authorities in multiple countries.
124
They had the base of the tusk so they could take a sample right along the pulp cavity, the ivory that formed just before death.
125
So we wanted to see, well, how recently were these animals killed relative to the time their ivory was seized?
126
And we were shocked to find that the vast majority,
127
literally almost all, the ivory for savannah elephants were killed within two years of the time their ivory was seized
128
and for forest elephants within three years of the time their ivory was seized.
129
But in a follow -up study of more recent seizures, Sam and his colleagues found nine tusks that dated back to the 1980s.
130
It seemed that they had been stolen or sold out of a government stockpile in Burundi, where they were supposed to be locked up for good.
131
Scientific discovery is unpredictable and opportunistic.
132
It sprouts from whatever puddles of data it can get.
133
And it can get less than we often assume.
134
Without the nuclear escalation of the Cold War, we wouldn't have a way to date elephant ivory from the 20th century.
135
Bomb carbon has also been pulled from canvas and paint to catch forgeries, from wine and whiskey to fact -check their vintage,
136
from the eye of a Greenland shark to confirm its remarkable lifespan ban.
137
It has helped Gianluca determine whether unmarked graves in Cyprus came from violent conflicts in the 60s and 70s.
138
More than 2 ,000 persons simply disappeared.
139
Of course they were killed.
140
And in some cases they could really find,
141
identify the person, name, and return the rest to families for a proper burial.
142
And it's very touching.
143
But at some point in the last few years, carbon -14 returned to its pre -bomb ratio in the air.
144
And that has happened faster than it would have if we weren't diluting the signal by burning fossil fuels, which contain carbon -12 but not carbon -14.
145
It's just a weird quirk of history that we're in this perfect period where the bomb pulse is a useful tool.
146
Yeah, and it's over.
147
hey wait
148
but how is bomb pulse dating different from traditional radiocarbon dating
149
i'm going to explain this really quick we'll make this a bonus video
150
that anyone can watch for free by joining our patreon okay so this show
📺 نفس القناة
C13
Why is this one spot not warming?
IELTS PrepTOEFL PrepUniversity Students
C12
Dog vision, explained
University StudentsWorking Adults
B23
Do we need more kids? A research showdown.
IELTS PrepTOEFL PrepUniversity Students
B23
When Siberia thaws, what emerges?
IELTS PrepTOEFL PrepUniversity Students
B2What the actual science says about "brain rot"
Daily ConversationUniversity StudentsWorking Adults
✨ فيديو موصى به
B258 جمل
Inside a $1 Billion Marble Quarry — How Luxury Stone Is Really Made
Business EnglishUniversity StudentsWorking Adults
B2112 جمل
The unpopular idea that would save San Francisco
Business EnglishDaily ConversationUniversity Students
C16
47 جمل
The most interesting "hack" in history...
American AccentBusiness EnglishUniversity StudentsWorking Adults
C17
37 جمل
3 Reasons Why Nuclear Energy Is Terrible! 2/3
IELTS PrepTOEFL PrepUniversity Students
B22
279 جمل
ABC World News Tonight With David Muir – Full Episode October 10, 2026
Business EnglishDaily ConversationUniversity Students
C13
330 جمل
Why Cold Drinks Were Deadly Before 1914
Business EnglishUniversity StudentsWorking Adults
C1101 جمل
Don’t Be the Thief of Your Own Life | True Story of A Famous Sign Painter
Business EnglishUniversity StudentsWorking Adults
C13
195 جمل
What is This $3BN Machine Under New York?
British AccentBusiness EnglishUniversity StudentsWorking Adults
C15
36 جمل
Underwater Archaeological Sites | IELTS Listening Test Part-4 | 22.03.2025 Real Examination Question
IELTS PrepUniversity StudentsWorking Adults
C15
108 جمل
Polymers: Crash Course Chemistry #45
IELTS PrepTOEFL PrepCambridge Exam Prep
B21
67 جمل
The challenge of counterfeits in the digital age | Vietnam Today
Business EnglishUniversity StudentsWorking Adults
B214
45 جمل
What makes art so expensive? | CNBC Explains
Business EnglishDaily ConversationUniversity Students
المفردات وملاحظات التحدث لهذا الدرس
يحتوي هذا الفيديو على 150 جملة و2027 كلمة للتدرب على الترديد. مدة الكلام 12:53. يتكلم المتحدث بسرعة طبيعية، نحو 157 كلمة في الدقيقة، قريبة من المحادثة اليومية. 80% فقط من الكلمات ضمن أكثر 3,000 كلمة شيوعًا في الإنجليزية، فالمفردات صعبة نسبيًا.
أهم المفردات في هذا الفيديو
15 كلمة من الفيديو تستحق التعلّم، مع النطق والمعنى:
| الكلمة | النطق | المعنى |
|---|---|---|
| ivory اسم | /ˈaɪv(ə)ɹi/ | عَاج, عَاجِيّ |
| elephant اسم | /ˈɛlɪfənt/ | فِيل, فيل |
| pulse اسم | /pʌls/ | نَبْض, نَبْضَة |
| seize فعل | /ˈsiːz/ | إِسْتَوْلَى عَلَى |
| capture فعل | /ˈkæp.(t)ʃɚ/ | أَسَرَ |
| researcher اسم | /ˈɹiˌsɝ.t͡ʃɚ/ | بَاحِث, بَاحِثَة |
| nitrogen اسم | /ˈnaɪ.tɹə.d͡ʒən/ | نَيْتُرُوجِين m or نِيتْرُوجِين, آزُوت |
| concentration اسم | /ˌkɑn.sənˈtɹeɪ.ʃən/ | تَرْكِيز |
| dealer اسم | /ˈdiːlə(ɹ)/ | تَاجِر, تَاجِرَة |
| statue اسم | /ˈstæt͡ʃu/ | تِمْثال, دُمْيَة |
| antique صفة | /ˌanˈtiːk/ | عَتِيق, قَدِيم |
| relative اسم | /ˈɹɛl.ə.tɪv/ | قَرِيب, قَرِيبَة |
| atmosphere اسم | /ˈætməsˌfɪɹ/ | جَو, غِلَاف جَوِّيّ |
| compare فعل | /kəmˈpɛɚ/ | قَارَنَ |
| ratio اسم | /ˈɹeɪ.ʃoʊ/ | نِسْبَة |
الأفعال المركبة التي ستسمعها
| الكلمة | المعنى |
|---|---|
| turn over فعل | قَلَبَ |
نطق يحتاج إلى انتباه
يستخدم المتحدث 19 من الصيغ المختصرة، مثل we're, I'm, don't. انطقها بصيغتها القصيرة كما تسمعها.
- أصوات “th”: smooth /smuːð/, mathematics /mæθ(.ə)ˈmæt.ɪks/
- أصوات “sh” و“zh”: capture /ˈkæp.(t)ʃɚ/, concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, ratio /ˈɹeɪ.ʃoʊ/, explosion /ɛkˈsploʊ.ʒən/, seizure /ˈsi.ʒɚ/
- الكلمات الطويلة — انتبه لموضع النبر: concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, naturally /ˈnæt͡ʃ.(ə.)ɹə.li/, unusual /ʌnˈjuːʒ(u)əl/, photographer /fəˈtɑ.ɡɹə.fɚ/, biology /baɪˈɑ.lə.d͡ʒi/
كيف تتدرب بهذا الفيديو
- استمع إلى الفيديو كاملًا مرة واحدة دون أن تتكلم، ودوّن الكلمات التي لا تعرفها.
- ابدأ بسرعة 0.75×، وردّد جملة جملة، ثم عُد إلى السرعة العادية عندما يصبح الأمر سهلًا.
- سجّل صوتك وقارنه بالأصل، مع الانتباه إلى كلمات مثل ivory, elephant, pulse.
القواعد في هذا الفيديو
أكثر التراكيب التي يستخدمها المتحدث، مع العبارات نفسها من الفيديو:
| التركيب | في الفيديو |
|---|---|
| المبني للمجهول be + اسم المفعول — التركيز على ما يحدث لا على من يفعله | was taken · has been moved · be fed |
| المضارع التام have/has + اسم المفعول — حدث ماضٍ ما زال له أثر الآن | has been moved · has declined · has happened |
| جمل الوصل who / which + جملة — معلومة إضافية عن شخص أو شيء | people who were · Storyblocks, which is · atoms, which have |
ما هي تقنية التظليل الصوتي؟
التظليل الصوتي (Shadowing) تقنية تعلم لغة مدعومة علمياً، طُورت أصلاً لتدريب المترجمين الفوريين المحترفين. الطريقة بسيطة لكنها قوية: تستمع لصوت إنجليزي أصلي وتكرره فوراً بصوت عالٍ — كظل يتبع المتحدث بتأخير 1-2 ثانية. تُظهر الأبحاث تحسناً كبيراً في دقة النطق والتنغيم والإيقاع وربط الأصوات والاستماع والطلاقة.