Shadowing Practice: Why Does Fire BURN? Feynman's Answer Will DESTROY Your Reality - Learn English Speaking with Video
בחר מצב תרגול
כל מצב פותח חדר תרגול במסך מלא.
298 משפטים
אם המשפטים קצרים או ארוכים מדי, לחץ על ערוך כדי להתאים אותם.
1
Why does fire exist?
2
Simple question.
3
You've seen fire a thousand times.
4
Campfires, candles, stoves.
5
You strike a match, something burns, flames appear. But why?
6
Most people never ask.
7
Fire just is.
8
It's hot, it's bright, it destroys things.
9
That's all you need to know, right?
10
Wrong wrong.
11
When you really ask what fire is, when you dig into what's actually happening when something burns, you discover something so beautiful,
12
so perfectly connected to everything else in nature, that it changes how you see the world.
13
Fire is not just a thing that happens.
14
Fire is a window into how atoms behave, how energy energy moves, how the sun powers everything,
15
and why trees exist in the first place.
16
Let me show you.
17
Start with a piece of wood, dead trees sitting there doing nothing,
18
and air, oxygen in the air floating around, also doing nothing.
19
The wood has been sitting there, the oxygen has been there the whole time.
20
Nothing's happening.
21
They're just there.
22
But the atoms like each other to different degrees.
23
Oxygen, for instance, in the air would like to be next to carbon.
24
And if they're getting near each other, they snap together.
25
But here's the problem.
26
If they're not too close, though, they repel and they go apart.
27
So they don't know that they could snap together.
28
This is the fundamental tension.
29
Carbon and oxygen want to be together.
30
Being together releases energy, a lot of energy.
31
That's the stable state, the low energy configuration.
32
But to get there, they have to first get close.
33
And getting close means climbing over a barrier.
34
It's just as if you had a ball that was trying to climb a hill, and there was a hole it could go into, like a volcano hole, a deep one.
35
It's rolling along.
36
It doesn't go down in the deep hole, because if it starts to climb the hill, it rolls away again.
37
But if you could make it go fast enough, it'll fall into the hole.
38
And so if you have something like wood and oxygen, there's carbon in the wood from a tree, and the oxygen comes and hits the carbon,
39
but not hot enough, it just goes away again.
40
And the air is always coming.
41
Nothing's happening.
42
The atoms are bouncing off each other constantly millions of collisions every second, but they're not reacting because they don't have enough energy.
43
They hit, they bounce, they separate, over and over.
44
The wood just sits there.
45
The oxygen just floats around.
46
Nothing changes.
47
This can go on for years, decades, centuries.
48
A piece of wood can sit in the presence of oxygen for a thousand years and nothing happens.
49
The atoms want to react, but they can't get over that barrier.
50
If you can get it faster by heating it up somehow, somewhere, somehow, get it started.
51
A few of them come fast.
52
They go over the top, so to speak.
53
They come close enough to the carbon and snap in.
54
And that gives a lot of jiggly motion, which might hit some other atoms, making those go faster so they can climb up and bump against other carbon atoms.
55
And they jiggle, and they make others jiggle, and you get a terrible catastrophe, which is one after the other.
56
All these things are going faster and faster and snapping in, and the whole thing is changing.
57
That catastrophe is a fire.
58
It's just a way of looking at it.
59
And these things are happening.
60
They perpetuate.
61
Once it gets started, it keeps on going.
62
The heat makes the other atoms capable of reacting to make more heat, to make other atoms, and so on.
63
This is the key to understanding fire.
64
It's not that something magical happens when you light a match.
65
It's that you're giving a few atoms enough energy to get over that barrier.
66
And once they do, they release energy.
67
That energy makes other atoms move faster.
68
Those atoms get over the barrier.
69
They release more energy, and so on.
70
It's exponential growth.
71
One reaction triggers two.
72
Two trigger four.
73
Four trigger eight.
74
The number of reacting atoms doubles and doubles and doubles.
75
Within a fraction of a second, you have billions of atoms all snapping together simultaneously.
76
That's why fire explodes into existence.
77
It's not gradual.
78
It's sudden.
79
because it's a chain reaction, a runaway feedback process.
80
So this terrible snapping is producing a lot of jiggling.
81
And if I put, with all that activity of the atoms there, and I put a cup of coffee over that mass of wood that's doing this, it's going to get a lot of jiggling.
82
So that's what the heat of the fire is.
83
Heat is not a substance.
84
It's not a fluid that flows.
85
Heat is atomic motion.
86
The faster atoms jiggle, the hotter something is.
87
When fire releases energy, that energy goes into making atoms move faster.
88
That's heat.
89
That's temperature.
90
That's what you feel when you hold your hand near a flame.
91
Fire is not a substance.
92
It's not a thing.
93
Fire is a process.
94
It's this catastrophic chain reaction where atoms are snapping together faster and faster, releasing energy, making other atoms move faster,
95
which makes more atoms snap together.
96
It's a cascade.
97
Once it gets started, it feeds on itself.
98
The heat from the reactions provides the energy needed to make more reactions happen.
99
It's self -sustaining.
100
That's why fire spreads.
101
That's why it's hard to stop.
102
The heat makes atoms jiggle fast enough to react.
103
The reactions produce more heat.
104
The more heat makes more atoms react around and around.
105
A feedback loop.
106
And the only way to stop it is to break the loop cool it down below the threshold, remove the fuel, remove the oxygen,
107
cut off one leg of the triangle and the process collapses.
108
And then of course if you see this is what happens when you just start to think, you just go on and on and wonder how did it get started.
109
Why is it that the woods been sitting around all this time with the oxygen all this time
110
and it didn't do this earlier?
111
Where did I get this from?
112
Well, it came from a tree, and the substance of a tree is carbon.
113
And where did that come from?
114
That comes from the air.
115
It's carbon dioxide from the air.
116
People look at trees and they think it comes out of the ground, that plants grow out of the ground.
117
But if you ask where the substance comes from, you find out, where does it come from?
118
The trees come out of the air.
119
They surely come...
120
No, they come out of the air.
121
This is one of the most beautiful misunderstandings in all of nature.
122
Everyone knows trees grow from the ground.
123
You plant the seed in soil, the tree grows.
124
Obviously, it came from the soil, right?
125
Wrong.
126
The carbon dioxide in the air goes into the tree, and it changes it, kicking out the oxygen
127
and pushing the oxygen away from the carbon and leaving the carbon substance with water.
128
Water comes out of the ground, you see.
129
But how did it get in there?
130
It came out of the air, didn't it?
131
It came down from the sky.
132
So in fact, most of a tree, almost all of the tree, is out of the ground.
133
I'm sorry, it's out of the air.
134
There's a little bit from the ground, some minerals, and so forth.
135
The minerals give you the ash when you burn wood.
136
That tiny bit of residue left behind, that came from the ground.
137
But the wood itself, the bulk of the tree, the substance that burns, that's carbon from the air.
138
That's water from the rain.
139
Almost nothing came from the soil.
140
Now let me prove it to you.
141
Take a pot of soil.
142
Weigh it.
143
Plant the seed.
144
Water it for years.
145
Let the tree grow big and heavy.
146
Now dig up the tree and weigh the soil again.
147
The soil weighs almost the same as it did before, maybe a tiny bit less.
148
Some minerals got absorbed.
149
But the The tree weighs hundreds of pounds more than it did as a seed.
150
Where did all that mass come from?
151
Not from the soil.
152
The soil didn't move hundreds of pounds.
153
It came from the air.
154
This experiment has been done.
155
The Dutch scientist Jan -Baptiste van Helman did it in the 1600s.
156
He was trying to figure out where plant mass comes from.
157
He weighed everything carefully.
158
The soil barely changed weight.
159
The tree gained enormous weight.
160
He concluded correctly that the tree did not come from the soil, but he thought it came from the water.
161
He was close.
162
The water is part of it, but most of the mass is carbon pulled directly out of carbon dioxide in the air.
163
Now, of course, I told you the oxygen and carbon stick together very tight.
164
How is it the tree is so smart as to manage to take the carbon dioxide, which is the carbon and oxygen nicely combined, and undo that so easy.
165
Life.
166
Life has some mysterious force?
167
No. The sun is shining.
168
And it's the sunlight that comes down and knocks the oxygen away from the carbon.
169
So it takes sunlight to get the plant to work.
170
And so the sun all the time is doing the work of separating the oxygen away from the carbon.
171
The oxygen is some kind of terrible byproduct
172
which it spits back into the air and leaving the carbon and water and stuff to make the substance of the tree.
173
This is what makes life on earth possible.
174
The sun is doing work, real, physical work.
175
It's pumping energy into the system.
176
That energy gets used to push systems away from equilibrium, to create order out of disorder, to build structure.
177
Trees are constantly doing this, sucking in carbon dioxide, tearing it apart, building themselves out of the carbon, releasing the oxygen back into the atmosphere.
178
That's what photosynthesis is.
179
It's the tree using energy to undo what fire does.
180
Fire takes carbon and oxygen and snaps them together.
181
Trees take carbon dioxide and rip it apart.
182
The tree is using sunlight to do work, to store energy, to build structure.
183
And that structure, that's potential energy.
184
The carbon and oxygen are held apart.
185
They want to be together, but they're separated.
186
Energy is stored in that separation.
187
And then when we take the substance of the tree and stick it in the fireplace, and there's all the oxygen made by these trees and all the carbon,
188
they would much prefer to be close together again.
189
And once you let the heat get it started, it continues, and it makes an awful lot of activity while it's going back together again.
190
And all this nice light and everything comes out, and everything is being undone.
191
You're going back from carbon and oxygen back to carbon dioxide.
192
And the light and heat that's coming out, that's the light and heat of the sun that went in.
193
So it's sort of stored sun that's coming out when you burn a log.
194
Think about that for a second.
195
The tree spent years collecting sunlight, bit by bit, photon by photon, using that energy to pull carbon out of the air and build itself.
196
It stored that energy in its structure.
197
Then you cut down the tree.
198
You let the wood dry.
199
You stack it in your fireplace and when you light it, all that stored sunlight comes pouring back out.
200
The carbon that the tree worked so hard to separate from oxygen is collapsing back together.
201
The energy that was stored is being released.
202
Fire is just stored sunlight escaping.
203
A log burning in your fireplace is the sun shining again.
204
The light you see flickering in the flames, that sunlight that fell on leaves five years ago, ten years ago, fifty years ago,
205
stored as chemical bonds, released all at once.
206
Every photon from the fire is, in a sense, a recycled photon from the sun.
207
The energy is the same.
208
It went in as sunlight, got stored as structure, and comes back out as firelight.
209
Now, you might ask, why doesn't the wood just spontaneously catch fire?
210
If carbon and oxygen want to be together so badly, why do you need the lighter match?
211
Because of that hill I mentioned earlier, the activation energy.
212
At room temperature, the atoms aren't jiggling fast enough to get over the hill.
213
They're bumping into each other, but they're not reacting.
214
The wood and the oxygen are stuck in what we call a metastable state.
215
They want to react, but they can't get started.
216
It's like a boulder balanced on Papua Hill.
217
It wants to roll down.
218
That's the lower energy state.
219
But it's sitting in a little depression at the top.
220
It's stable as long as nothing pushes it.
221
But if you give it just a little nudge, it rolls down and releases a lot of energy.
222
That's what the match does.
223
It provides the nudge.
224
It heats up a small region of the wood, making those atoms jiggle faster, getting them over the activation barrier.
225
Once a few reactions start, they produce enough heat to trigger more reactions, and the fire spreads.
226
This is why things don't just spontaneously combust.
227
The universe is full of metastable states, systems that want to release energy but can't get started.
228
Wood and oxygen, gasoline and air, food and oxygen in your cells.
229
They're all waiting for a trigger, a spark, an enzyme, something to get them over that initial barrier.
230
And once they start, they run on their own.
231
Here's another thing that should blow your mind.
232
The oxygen in the air, where did that come from? from trees, from plants, from photosynthesis.
233
For billions of years, plants have been ripping carbon dioxide apart.
234
keeping the carbon and spitting out the oxygen.
235
All the oxygen you breathe, all the oxygen in the atmosphere, it's waste.
236
It's a byproduct.
237
Plants don't want it.
238
They throw it away.
239
The early earth had almost no free oxygen.
240
The atmosphere was carbon dioxide, nitrogen, water vapor.
241
Then photosynthetic organisms evolved.
242
They started dumping oxygen into the atmosphere as waste.
243
For them, oxygen was poisoned.
244
Many of those early organisms died out when oxygen levels rose.
245
But some organisms evolved to use that oxygen, to burn food with it, to extract energy from it.
246
And that oxygen is what makes fire possible.
247
So here's the cycle.
248
The sun shines.
249
Plants use that sunlight to break apart carbon dioxide, building themselves out of carbon and releasing oxygen.
250
Animals, including you, eat the plants or eat other animals that ate plants.
251
And you burn that carbon, combining it back with oxygen to release energy.
252
That burning happens inside your cells.
253
It's called respiration.
254
It's the same process as fire, just slower and more controlled.
255
You're taking carbon -based molecules and combining them with oxygen to release energy.
256
The carbon dioxide you exhale is the same carbon dioxide the plants absorb.
257
It's a cycle, sun to plants to animals and back.
258
Carbon circulating, oxygen circulating, energy flowing.
259
Fire is just that cycle, sped up and visible.
260
When you burn wood in a fireplace, you're doing exactly what your cells do when they burn sugar.
261
Same reaction, carbon plus oxygen makes carbon dioxide and releases energy.
262
The only difference is speed and control.
263
Your cells do it slowly, carefully, capturing the energy in useful molecules like ATP.
264
Fire does it all at once, releasing the energy as heat and light.
265
But it's the same chemistry, the same process.
266
You are, in a very real sense, a slow fire.
267
Let me make this even more concrete.
268
When you burn wood, you're converting chemical energy into heat and light.
269
The chemical energy was stored in the bonds holding the wood's molecules together.
270
Those bonds took energy to create.
271
That was the sunlight the tree absorbed.
272
Breaking the bonds and forming new bonds, carbon dioxide and water, releases that energy.
273
The heat you feel, that's atoms jiggling faster because energy was released.
274
The light you see, that's atoms and molecules getting excited, literally electrons jumping to higher energy levels,
275
and then falling back down, emitting photons.
276
When carbon and oxygen snap together, the energy release doesn't just disappear.
277
It goes into motion, atoms moving faster, molecules vibrating, electrons jumping to higher orbits.
278
And when those electrons fall back down, they emit light.
279
That's the glow of the fire.
280
That's the flame.
281
Different atoms emit different colors.
282
Sodium makes yellow, copper makes green, strontium makes red.
283
That's why fireworks work work.
284
Different chemicals burn with different colors because they have different electron configurations.
285
The smoke, that's tiny particles of carbon and other stuff that didn't fully react,
286
floating up because they are hot and less dense than the surrounding air.
287
The ash, that's the minerals, the stuff that wasn't carbon, the bits that came from the soil,
288
that's the tiny fraction of the tree that didn't come from the air.
289
Everything else, the carbon, the hydrogen, the oxygen, has turned into gas.
290
Carbon dioxide and water vapor, invisible products floating away.
291
The mass didn't disappear.
292
It turned into gas and drifted off.
293
Now here's the question you should be asking.
294
Next question.
295
How is it the sun is so jiggly, so hot?
296
That's a different story.
297
I've got to stop somewhere.
298
I'll leave you something to imagine.
הורד אפליקציה
כל מה שאתה צריך כדי לדבר בשטף
הגיית AIציון לכל משפט
תרגול IPAשלוט בכל צליל
אוצר מיליםבנה את מאגר המילים שלך
משחק אוצר מיליםלמד תוך כדי משחק
אותו ערוץ
FOR YOU
המלץ על סרטון
C11
222 משפטים
How Fire Made Us Human
Daily ConversationUniversity StudentsWorking Adults
B23
7 משפטים
Why is Nuclear Fusion so Hard? - Nuclear Engineer Explains #nuclear
Daily ConversationUniversity StudentsWorking Adults
C11
654 משפטים
Stuart & Cliffe Knechtle | Do Agnostics Just Want To Have Control? | Give Me an Answer
Daily ConversationUniversity StudentsWorking Adults
B23
17 משפטים
Why carbon? It's the backbone of life! - Suzanne Simard | UBC Earth Day
Daily ConversationUniversity StudentsWorking Adults
B22
9 משפטים
A reason why you should study hard by Richard Feynman in less 50 seconds.
Daily ConversationUniversity StudentsWorking Adults
B23
303 משפטים
What If you Could See the 4th Dimension?
Daily ConversationUniversity StudentsWorking Adults
C12
227 משפטים
Stop Rehearsing The Life You Don’t Want | Dr Joe Dispenza Motivation
Daily ConversationUniversity StudentsWorking Adults
B24
122 משפטים
How Chemistry Shapes Great Films (And Makes Them Unforgettable)
American AccentDaily ConversationUniversity StudentsWorking Adults
B22
109 משפטים
How ELECTRICITY works - working principle
Daily ConversationUniversity StudentsWorking Adults
C11
246 משפטים
Why Life Feels Boring (And Skyrim Doesn’t)
Daily ConversationUniversity StudentsWorking Adults
B21
196 משפטים
Something Weird Happens When You See How Connected Everything Is
Daily ConversationUniversity StudentsWorking Adults
C1552 משפטים
The Professor Who Taught People How To Think (1962)
Daily ConversationUniversity StudentsWorking Adults
אוצר מילים והערות הגייה לשיעור הזה
שיעור הדיבור הזה ברמה B2 מבוסס על הסרטון “Why Does Fire BURN? Feynman's Answer Will DESTROY Your Reality”. המילים שחוזרות הכי הרבה: carbon, oxygen, energy, tree, atoms. בסרטון הזה יש 298 משפטים ו-2934 מילים לתרגול Shadowing. הדיבור נמשך 19:33. הדובר מדבר בקצב טבעי של כ-150 מילים בדקה, קרוב לשיחה יומיומית. 83% מהמילים נמצאות בין 3,000 המילים הנפוצות ביותר באנגלית; כדאי ללמוד את השאר לפני שמתחילים.
אוצר מילים מרכזי בסרטון הזה
15 המילים המתקדמות ביותר בסרטון, עם ההגייה והמשמעות שלהן:
| מילה | הגייה | משמעות |
|---|---|---|
| atom שם עצם | /ˈætəm/ | אָטוֹם |
| barrier שם עצם | /ˈbæɹi.ə/ | מַחְסוֹם |
| photon שם עצם | /ˈfəʊtɒn/ | פוטון |
| molecule שם עצם | /ˈmɑ.lɪ.kjul/ | מוֹלֵקוּלָה |
| weigh פועל | /weɪ/ | שקל |
| fireplace שם עצם | /ˈfaɪɹpleɪs/ | אָח, קָמִין |
| float פועל | /fləʊt/ | צָף |
| mineral שם עצם | /ˈmɪn.ə.ɹəl/ | מִינֶרָל, מַחְצָב |
| flame שם עצם | /fleɪm/ | לֶהָבָה, אֵשׁ |
| organism שם עצם | /ˈɔɹ.ɡəˌnɪz.əm/ | אוֹרְגָּנִיזְם, יְצוּר |
| absorb פועל | /æbˈsɔɹb/ | ספג |
| shine פועל | /ʃaɪn/ | זָרַח |
| circulate פועל | /ˈsɝ.kjʊˌleɪt/ | הסתובב |
| photosynthesis שם עצם | /ˌfoʊ.toʊˈsɪn.θə.sɪs/ | פוטוסינתזה |
| vapor שם עצם | /ˈveɪpɚ/ | אֵד |
Phrasal verbs שתשמעו
| מילה | הגייה | משמעות |
|---|---|---|
| come out פועל | /ˌkʌm ˈaʊt/ | יָצָא |
| cut down פועל | כָּרַת, חָטַב | |
| figure out פועל | הֵבִין, מצא תשובה |
משפטים שכדאי לחזור עליהם
משפטים קצרים ושלמים מהסרטון שאפשר להשתמש בהם בשיחה יומיומית:
- You've seen fire a thousand times.
- That's all you need to know, right?
- Where did I get this from?
- It came out of the air, didn't it?
- I'm sorry, it's out of the air.
דקדוק בסרטון הזה
המבנים שהדובר משתמש בהם הכי הרבה, עם המילים המדויקות מהסרטון:
| מבנה | בסרטון |
|---|---|
| הווה מושלם ממושך (Present perfect continuous) have/has been + -ing — פעולה שהתחילה בעבר ועדיין נמשכת עכשיו | has been sitting · have been ripping |
| סביל (Passive voice) be + past participle — הדגש הוא על מה שקורה, לא על מי שעושה את הפעולה | has been done · are held · is stored |
| הווה מושלם (Present perfect) have/has + past participle — פעולה שקרתה בעבר ועדיין יש לה חשיבות או השפעה עכשיו | You've seen · has been · has been done |
| משפטי זיקה (Relative clauses) who / which + clause — מידע נוסף על אדם או דבר | catastrophe, which is · dioxide, which is |
הגייה ששווה לשים לב אליה
הדובר משתמש ב-36 קיצורים וצורות מקוצרות, כמו they're, didn't, you're. אמרו אותם בצורה הקצרה, כפי שאתם שומעים אותם.
- הצלילים של “th”: photosynthesis /ˌfoʊ.toʊˈsɪn.θə.sɪs/, threshold /ˈθɹɛʃ(h)oʊld/
- הצלילים של “sh” ו-“zh”: shine /ʃaɪn/, activation /ˌæktəˈveɪʃən/, fraction /ˈfɹæk.ʃən/, configuration /kənˌfɪɡ.əˈɹeɪ̯.ʃən/, respiration /ɹɛspɪˈɹeɪʃən/
- מילים ארוכות — שימו לב להטעמה: organism /ˈɔɹ.ɡəˌnɪz.əm/, photosynthesis /ˌfoʊ.toʊˈsɪn.θə.sɪs/, spontaneously /spɑnˈteɪ.ni.əs.li/, catastrophe /kəˈtæstɹəfi/, activation /ˌæktəˈveɪʃən/
צלילים שדוברי עברית מתקשים בהם:
- /w/ — שפתיים מעוגלות, לא /v/: weigh /weɪ/, firework /ˈfaɪɚˌwɚk/, perpetuate /pɚˈpɛt͡ʃəˌweɪt/, runaway /ˈɹʌnəweɪ/, equilibrium /ɛkwɪˈlɪbɹɪəm/
- /æ/ — פתוח יותר מה-“אֶ” העברית, לא כמו “a” ב-“cup”: atom /ˈætəm/, react /ɹiːˈækt/, barrier /ˈbæɹi.ə/, absorb /æbˈsɔɹb/, catastrophe /kəˈtæstɹəfi/
- /r/ — הלשון לא נוגעת בשום מקום, לא ה-“ר” הגרונית: react /ɹiːˈækt/, barrier /ˈbæɹi.ə/, fireplace /ˈfaɪɹpleɪs/, mineral /ˈmɪn.ə.ɹəl/, organism /ˈɔɹ.ɡəˌnɪz.əm/
איך לתרגל עם הסרטון הזה
- הקשיבו לכל הסרטון פעם אחת בלי לדבר, ורשמו את המילים שאתם לא מכירים.
- התחילו במהירות 0.75×, תרגלו Shadowing משפט אחר משפט, וחזרו למהירות רגילה כשזה מרגיש קל.
- הקליטו את עצמכם והשוו למקור, תוך תשומת לב למילים כמו atom, barrier, photon.
מהי טכניקת השאדואינג?
שאדואינג היא טכניקת למידת שפה מבוססת מדע שפותחה במקור להכשרת מתורגמנים מקצועיים ופופולרית על ידי הפוליגלוט ד"ר אלכסנדר ארגואלס. השיטה פשוטה אך עוצמתית: אתה מקשיב לאודיו באנגלית ילידית וחוזר עליו בקול רם מיד — כמו צל העוקב אחרי הדובר עם עיכוב של 1–2 שניות בלבד. בניגוד להאזנה פסיבית או תרגילי דקדוק, שאדואינג מכריח את המוח והשרירים בפה לעבד ולשחזר דפוסי דיבור אמיתיים בו זמנית. מחקרים מראים שזה משפר משמעותית את דיוק ההגייה, האינטונציה, הקצב, הדיבור המחובר, הבנת השמיעה ושטף הדיבור — מה שהופך אותו לאחת השיטות היעילות ביותר להכנה לIELTS Speaking ולתקשורת באנגלית בעולם האמיתי.