
Chinese: 
自從哥白尼發現了並非宇宙的中心，
我們經常強調地球很可能平凡無奇。
自從哥白尼發現了並非宇宙的中心，
我們經常強調地球很可能平凡無奇。
然而，事情很可能相反......
今天我們回到「大過濾」系列，繼續來看費米悖論。
注意，費米悖論（浩瀚無垠的宇宙中竟看不到智慧生命）的一個常見解釋，
是「奧坎剃刀原則」的應用，
即：我們看不到外星文明，因為根本沒有
即：我們看不到外星文明，因為根本沒有
雖然我們可假設他們曾經存在，但擁有科技後都毀滅了

Portuguese: 
 
 
 
 
 
 
 
 
 

English: 
Ever since Copernicus showed us we’re not
the center of the Universe, we have tried
to emphasize that Earth is probably not that
special or unique.
As it turns out, that might not be case after
all.
So today we return to the Great Filters series
to continue our look at the Fermi Paradox.
As a reminder, one of the more popular solutions
to the Fermi Paradox, the strange-seeming
absence of other intelligent life in our huge
and ancient Universe, is that Occam’s Razor
applies in this case and that the reason for
the seeming absence of other civilizations
is exactly that, they don’t exist.
While we can consider the possibility that
they existed in the past, but all died out

English: 
after getting technology, the alternative
explanation is that they just don’t occur
much.
Since there is no obvious reason why they
wouldn’t, we tend to assume that there are,
instead, a lot of little steps and conditions
involved in a planet becoming life-bearing
and staying that way long enough for life
to get intelligent.
Each of those steps and conditions is called
a filter, basically a hurdle you would need
to get past that filters out potential civilizations
arising on a planet.
Last time we defined a number of different
types of filters, from lesser to greater,
the former being ones that most will pass
through, coin flip odds or better, while the
latter is more comparable to lottery odds
or less.
I also mentioned before that you can often
group related smaller filters into one Great
Filter, though you can’t always do the reverse
and break up a great filter into a collection
of smaller component ones.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
另一個解釋是文明本來就不常出現。
另一個解釋是文明本來就不常出現。
畢竟沒有明顯的理由如此假設，我們通常認為
一個足以維持生命夠久，以至於發展智慧的行星
需要累積許多步驟
這每一步就是所謂的「過濾」，即障礙
它會過濾掉文明發展的可能性
上次我們看到了各種過濾，從小到大，
「小過濾」是指多數文明都能通過（一半以上機率），
要通過「大過濾」至少比中樂透還難。
我還說過可以把一組較小的過濾統合成大過濾，
但不見得可以反過來，把一個大過濾拆解成很多小過濾
但不見得可以反過來，把一個大過濾拆解成很多小過濾

Chinese: 
本系列著重在可能存在的「大過濾」，上次討論到三個
我們這次只集中討論一個
今天的重點是流行的「地球殊異假說」，也就是
地球和我們太陽系，特別且幾乎唯一適合
智慧生命和科技文明
我得先強調「智慧和先進科技」，因為費米悖論
並不關心那些只長得出地衣的幽暗星球，
除非地衣也能發展出智慧文明，
建造太空船及無線電發射器。
除非地衣也能發展出智慧文明，
建造太空船及無線電發射器。
所以我們雖然可以指著冥王星之類的地方說
「受到放射性衰變或潮汐力加熱，
那裡的地下泥巴水坑可能有生命」
我們還可以把它納入外星生命的搜索對象

English: 
This series focuses on possible Great Filters
and while we discussed three last time, we
are only looking at one for this episode and
will generally stick to that.
Our focus for today is the famous “Rare
Earth” Hypothesis, and more specifically
the conditions about Earth and our solar system,
which might make it nearly uniquely suited
among planets to host intelligent life and
technological species.
I want to emphasize “intelligent and technologically
advanced” right up front, because for the
Fermi Paradox we don’t care about some barren
twilight planet hosting simple lichen, not
unless that lichen has developed a complex
and enlightened civilization building spaceships
and radio transmitters.
So while we can look at a place like Pluto
and say “Yes there’s a chance life might
develop there in some deep subsurface pocket
of muddy water warmed by nuclear decay or
tidal heating”, we can also rule it out
as a place to look for alien homeworlds.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
但那裡仍沒有足夠能量，
以維持複雜、快速運轉的生態系
來允許智慧生命發展。
大腦是非常昂貴耗能的器官，
而且在演化的每一步驟都須保持一定的大小
例如橡樹就沒有腦，因為對它的生存無益，
它沒有一項行為非得要大腦決策
因此除了波茲曼大腦之類的特殊案例，
那些純粹從隨機中浮現的意識，我們傾向認定
高能量的環境足以產生掠食者-獵物的軍備競賽
而且只要開始就會盡可能加快。
演化需要時間，尤其需要許多世代，越複雜的動物
會有更長的繁衍週期。細菌每小時都能分裂，我們不行

English: 
There’s just not enough energy flux there
to allow a complex and fast ecosystem that
would permit intelligence to arise.
Brains are very expensive in terms of energy
and organs demanding resources and have to
be constantly of value at every step of an
evolutionary progression.
An Oak Tree doesn’t have a brain, for instance,
because it would offer no advantage to its
survival, not when it has no means to implement
any decisions that brain makes.
So outside of the specific case of a Boltzmann
Brain or something parallel, where the brain
just sort of blunders into existence fully
formed, we are justified in assuming only
a high-energy environment could offer enough
life to generate such a predator-prey mental
arms race and do so quickly enough for it
to have already happened.
Evolution takes time, but more importantly,
it takes generations; and more complex critters
tend to have longer generational cycles, bacteria
can reproduce hourly, we do not.

Chinese: 
估計所有曾經活過的人類約一千億，即10^11人
我們可以假設多種哺乳動物比這多十億倍，即10^20，
繁殖週期約為一年或更長。
昆蟲數量更多且歷史更悠久，
可以假設再多十億倍，10^29，加上細菌可能又一兆倍
所有曾經活過的細菌約10^42個
這每個生命體都算一個演化事件，大多是失敗或徒勞的
但你大概知道需要多少這種事件，才能演化出一群
圍著營火、磨著石斧的隊群，
質問天上那些亮點的意義。
大多數演化事件與你的基因組成無關，

English: 
There have been an estimated 100 billion humans
who have ever lived, or 10^11.
We can estimate that maybe a billion times
that many mammals have ever lived, or 10^20,
most on an annual or longer generational cycle.
Throw in insects who are far more numerous
and have been around much longer, and you
can go up about a billion times more, 10^29,
and if we include bacteria, perhaps a trillion
times that many, 10^42, have ever lived.
Each of those organisms represents an evolutionary
event, mostly a failed or meaningless one,
but that gives you an idea how many of these
events need to take place to generate some
folks sitting around a campfire sharpening
stone axes and wondering what the pretty points
of light in the sky mean.
Most of those events had nothing to do with
your genetic makeup, a better designed oak

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
更好的橡樹葉子同你的DNA無關；
但更高的智能是對整個生態系的回應，
這就和你有關。
一隻生物要學會吃草蠻容易，無須太多頭腦或感官，
那些東西是用來應對吃同一片草或吃你的生物。
一隻生物要學會吃草蠻容易，無須太多頭腦或感官，
那些東西是用來應對吃同一片草或吃你的生物。
一隻生物要學會吃草蠻容易，無須太多頭腦或感官，
那些東西是用來應對吃同一片草或吃你的生物。
我們以後會講更多關於大腦競賽的問題，
但今天我們僅用來強調
需要多少世代和演化事件才能發展出智慧。
需要多少世代和演化事件才能發展出智慧。
如果這很正常，我們就得出：
支持更少生物、
或生物必須演化較慢的星球，更難發展出科技
因為「演化事件」比較少。
公轉週期延長10％，則依賴季節每年繁殖一次的生命
演化速度慢10％，這還是樂觀的估計，

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
leaf is unrelated to your own DNA, but growing
intelligence is a reaction to the entire ecosystem
evolving so it does matter.
It’s not hard for an organism to learn to
eat grass properly, they don’t need a ton
of brains or sensory gear for that, they need
it for responding to other animals who either
want to eat the same grass or eat them.
We’ll talk more about the brain race in
the future, but for today I mention it primarily
to emphasize how many overall generations
and individual evolutionary events were needed
to get here.
If that’s fairly normal, then we have to
consider that any planet that can support
less life, or requires it to live slower,
is less likely to have gotten technology by
now because of fewer of those evolutionary
events.
Make the year 10% longer and critters that
breed annually around the food supply of seasons
evolve 10% slower, though that is probably
optimistic since they would need bigger food

English: 
stores to survive the longer winter and therefore
support fewer of those critters to do the
evolving.
We’ll talk about this more in the future,
but for now it’s important to remember that
we’re not discussing where life could exist,
or even where technology might eventually
develop, but where it is likely to have already
developed.
After all, the Universe is fairly young still.
We’ll start there.
Once the universe explodes into existence
it takes a long while to develop a structure
where Earth-like planets can be common, and
today we are going to try to assume that it
almost has to be an Earth-like planet to offer
a good chance for civilizations to emerge.
So what do we know about Earth that matters?
The first step is to ask about its basic position
in time and space.
Earth is not an old planet at all, the Universe
was about 9 billion years old already when
it formed.
If we compare the entirety of time to one
24-hour day starting at midnight, Earth formed

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
因為需要儲藏食物熬過冬天，能用來發展的能量更少。
因為需要儲藏食物熬過冬天，能用來發展的能量更少。
以後會再談到，現在我們要記住
不是在討論生命存在與否，甚至科技發展於否，
而是哪裡最容易發展出科技。
畢竟宇宙（以宇宙標準）還算年輕。從這裡說起。
畢竟宇宙（以宇宙標準）還算年輕。從這裡說起。
宇宙創生後需要漫長歲月，
才能發展出夠多
像地球這類行星，而今我們假設
幾乎必定要有像地球的行星才能發展文明。
像地球這類行星，而今我們假設
幾乎必定要有像地球的行星才能發展文明。
但我們怎知地球是否重要？
首先我們自問地球在時空中的位置。
地球不是個老行星，它誕生時宇宙已經90億年了。
地球不是個老行星，它誕生時宇宙已經90億年了。
如果以24小時算，宇宙在午夜創生，

English: 
at about 4 o’clock in the afternoon, two-thirds
of the way through the day.
Life didn’t crawl up on land till an hour
before midnight.
Now you already know that it took a long while
for enough heavy elements to form in dying
stars to produce rocky planets like Earth,
but it did not take that long.
Earth’s composition relates to the Metallicity
of our own Sun, that being all the stuff in
a star besides hydrogen and helium, the only
two elements that existed in any real quantity
prior to stars making them.
We often also look at this as the ratio of
Iron to Hydrogen in a star, iron incidentally
being the most abundant element on Earth,
just beating out oxygen, which is the third
most common element in the Universe.
The relation of those two is pretty important
as well, since our oxygen-rich atmosphere
only came after the iron in the upper crust
of the planet became saturated with more oxygen

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
則地球到下午四點才出現，一天已過三分之二
生命到午夜前一小時還沒登上陸地。
已知重元素需要長時間才能從死去的恆星釋出，
然後形成類地行星，但其實並沒有很久。
地球的組成和太陽的金屬量
（天文學上，指氫、氦以外所有元素）相關，
地球的組成和太陽的金屬量
（天文學上，指氫、氦以外所有元素）相關，
而氫與氦，是恆星唯二有意義的組成成份。
我們常以鐵：氫比例來看。鐵是地球上
最多的元素，稍微超過氧（宇宙中第三多的元素）。
最多的元素，稍微超過氧（宇宙中第三多的元素）。
鐵：氧比例也很重要，因為大氣層中的氧氣
必須在氧化完上層地殼所有鐵之後才得以積累，

Chinese: 
況且還有板塊運動不斷把新鮮的鐵送上來。
對高耗能生命，氧氣顯然很重要，因為光合作用
產生氧氣和我們所有食物。
氧氣也可能毒害之前的生命，它們依賴厭氧、
或其他更弱的能量來源，而非陽光
氧氣是很好的燃料（氧化劑）且在宇宙中含量豐富
因此生物應該偏好使用氧氣，
我們每天都吸將近一公斤
太陽的金屬量（Z）是0.0196，亦即少於2％的
太陽質量是氫、氦以外的元素。
如我所言，我們一般研究鐵：氫比例，主要是因為

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 

English: 
than it could sequester even with tectonic
activity turning over new iron.
Oxygen is obviously very important to high-energy
mobile lifeforms, as is the oxygenic photosynthesis
process that supplies all of our food and
releases that oxygen.
Oxygen that also consequently poisoned off
the life that lived before then and used anoxygenic
photosynthesis or other far weaker energy
sources that don’t rely on sunlight.
Likewise, oxygen is an excellent fuel, or
oxidizer, and its sheer abundance everywhere
in the Universe should tend to make it the
preferred substance for critters to consume,
we each use nearly a kilogram of it every
day.
Our sun’s metallicity, Z, is 0.0196, or
meaning just under 2% of the Sun’s mass
is stuff other than hydrogen and helium.
As I said, we are also often interested in
the iron-to-hydrogen ratio, partially because

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
it matters for planet formation, but mostly
because it’s a lot easier to determine both
iron and hydrogen content of stars than most
of the other stuff in them.
From this we can make a good guess at the
rest of elements.
Metallicity is a bit more intuitive though,
and is what I will use to discuss this.
However, if you go hunting for more data you
will see as many graphs with Fe/H on an axis
as Z for Metallicity, and it helps to avoid
confusion.
So the sun is 2% metals, and so essentially
were all of the early planets forming out
of the nebula that became our solar system.
That got quite hot and when the sun ignited
it started adding radiation and solar wind
to the mix.
Planets lost all their helium and neon, the
second and fourth most abundant elements in
the modern Universe.
They are quite light and easily blown away,
and being Noble gases they’re so aristocratic

Chinese: 
和行星生成相關，
更重要的是鐵和氫比其他元素更容易測量。
和行星生成相關，
更重要的是鐵和氫比其他元素更容易測量。
以此我們可以估算餘下元素的含量。
金屬量比較直覺，而我會用金屬量討論。
然而你若翻資料，你會找到鐵：氫比例（Fe/H）的表格
而非金屬量（Z），這點要清楚。
總之太陽金屬量是2％，
太陽系剛誕生的行星應該也都一樣。
總之太陽金屬量是2％，
太陽系剛誕生的行星應該也都一樣。
而一旦太陽點燃，便會加入輻射和太陽風。
而一旦太陽點燃，便會加入輻射和太陽風。
行星失去氦和氖，宇宙中第二和第四多的元素。
行星失去氦和氖，宇宙中第二和第四多的元素。
它們很輕，易被吹散，且作為惰性氣體

English: 
and snobby they won’t even hang out with
each other, let alone the peasant elements.
Hydrogen, oxygen, nitrogen and carbon are
all pretty light too, but they can form heavy
molecules that stuck around.
However the over-abundance of hydrogen meant
that most couldn’t find any dance partners
and so they also blew away.
Oxygen is likewise very common and will dance
with almost anyone, so most of the hydrogen
that didn't blow away paired up with them
as water.
So the warmer planets of the inner solar system
are rocky, not so much because they started
out with more of those elements than the Sun
or outer gas giants, but rather because those
are the main things that stuck around under
the heat.
Their absence from the thousands of exoplanets
we’ve found so far doesn’t indicate rarity,
it is just that it’s far easier to see big
planets and those close to their sun, so we
see a lot of very big and hot planets.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
它們彼此都不結合，更何況跟區區其他元素。
氫、氧、氮、碳也很輕，但能夠形成較重的分子
固定在星球上
然而壓倒性多數的氫，常找不到其他分子結合
於是也被吹散了。
氧數量夠多且來者不拒，因此多數留下來的氫
都與氧結合，形成水
因此內太陽系的行星多為岩石，並非因為
他們一開始就比太陽、氣體行星更多重元素
而是在高溫下只能保留這些物質
雖然在目前發現的數千科系外行星中佔比較少，
但這純粹因為大行星、靠近恆星的行星容易觀測
所以我們會看到很多巨大的炎熱行星。

English: 
It would seem a safe bet though, that you
need a metallicity decently close to our own
Sun’s or higher to get many large rocky
planets.
The metallicity of stars is always higher
the younger they are, not because they lose
that as they age, but because as the Universe
ages the amount of metals increases as more
and more stars go supernova so the younger
newer ones tend to be higher.
However, there are plenty of stars younger
than ours with lower metallicity and somewhat
older ones with higher metallicity.
Most aren’t however, we are pretty much
in the thick of the bell-curve in that regard.
You can find a fair number which are a billion
or more years older than ours with higher
metallicity, but they start getting very scant
at more than 8 billion years of age.
We can, however, safely conclude that systems
with lots of rocky planets with the same basic
composition as our own, have been quite common
since at least a billion years before our

Chinese: 
可以肯定，要有類似太陽或更高的金屬量
才造得出大量岩石行星
越年輕的恆星金屬量越高，不是因為失去金屬
而是隨著宇宙年歲增長，越來越多超新星爆炸
釋出金屬，剛形成的恆星金屬含量就更多
然而，還是很多低金屬的年輕恆星和高金屬的較老恆星
然而，還是很多低金屬的年輕恆星和高金屬的較老恆星
但這並非常態，我們還是在光譜的中央附近。
還是可以找到比太陽年長十億多年的恆星，
擁有較高金屬量，但超過八十億歲的已非常罕見。
不過我們很確定，擁有多個岩石行星、
成份類似我們太陽系的系統，至少比太陽早十億年

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
own came into existence, and perhaps a few
more.
We generally divide stars into populations
1 and 2, and really old ones are labeled population
3, based on how much metal they have.
That’s a very broad and arbitrary categorization,
so it might be that not all population 1 metal-rich
stars like our sun have enough metal or that
some population 2 stars do.
Indeed we’ve found planets around fairly
low metallicity stars too.
What this establishes however, is that we
can’t consider the metallicity of our own
sun and its age to be more than a lesser or
minor filter itself in terms of setting boundaries,
though those lesser filters can stack up as
we’ve discussed before.
Ditto the fact that we often discard the inner
galaxy as a place for life because of all
the radiation and higher star density sterilizing
planets or perturbing their orbits, but the

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
就已存在，可能還更早些。
恆星通常根據金屬量分為第一族和第二族，
最老的那些則是第三族。
這種分類蠻廣泛的，
不一定所有第一星族（金屬量多的恆星，類似太陽）
金屬量都比第二星族高。
確實也在金屬量相當低的恆星旁發現過行星。
重點是，我們太陽的金屬量或年齡限制
不會超過「小過濾」或「次過濾」級別，
雖然我們講過那些較小的過濾會加成。
同時我們放棄，星系核心附近生命的可能，
因為過多的輻射和高恆星密度會烘烤行星、干擾軌道

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
但我們銀河系的旋臂有不少第一星族，
故不太會影響。
但我們銀河系的旋臂有不少第一星族，
故不太會影響。
但謹記，離星系核心越遠，物質則越少。
但謹記，離星系核心越遠，物質則越少。
這構成星系的「適居帶」，太內側有輻射和重力干擾，
太外側則物質不足，
實際上不至於超過「小過濾」太多。
太外側則物質不足，
實際上不至於超過「小過濾」太多。
所以我們有兩個「小過濾」，就各自當作一半機率通過
最後再來加成，縱然這是樂觀估計，
這兩個通過機率應低於一半。
當然剛剛講的都只適用於旋臂穩定的螺旋星系，
其他種類的星系較不適居，我也曾提過，
討論費米悖論不能忽略其他星系。

English: 
spiral arms of our galaxy are quite heavy
in the metal-rich population 1 stars so this
isn’t much of a filter either.
It should be noted, though, that the further
you get from a galactic core in galaxies like
our own, the less metals you tend to have.
So we have a galactic Goldilocks zone, too
close, radiation and perturbation, too far
and there are not enough metals, but realistically
it is hard to argue this is much more than
a lesser filter.
So, that gives us two lesser filters so far,
we’ll treat both as 50/50 at the end when
we total everything up, though I suspect we’re
being generous for both and it’s more likely
less than 50/50.
Of course everything I just said applies only
to stable spiral arms galaxies; when you look
at other types, the conditions tend to be
less favorable and as I’ve mentioned on
this topic before, you can’t just write-off
other galaxies from the Fermi Paradox.

English: 
However, for today we will focus on our own
galaxy, so we can use its total stellar population
as our comparison number at the end and also
bypass further complicating stuff like quasars,
galactic mergers, and so on.
Though it is also worth remembering that our
own galaxy is a serious cannibal and has eaten
a ton of lesser galaxies, though by and large
this sort of process shouldn’t tinker too
much with how habitable various individual
solar systems are.
This and other factors have to be considered,
for example, a star’s orbit around a galaxy
being stable and not passing through the hazardous
core or too close to big dense pockets of
stars.
I will add that as another lesser filter and
we’ll call that the “Safe Galactic Orbit”
filter.
A lot of stars are also binaries or in packs
so dense that they would tend to destabilize
stable planetary orbits, and we will make
that our fourth lesser filter, again that’s
probably being generous.

Chinese: 
但今天我們只看本銀河系，
到最後直接用其恆星數推算，並忽略
但今天我們只看本銀河系，
到最後直接用其恆星數推算，並忽略
類星體、星系碰撞等。
且記住，我們銀河系也是吃過很多小星系的魔王
不過總括來說，這類過程不值得
在討論恆星系統的適居性時停太久。
不過總括來說，這類過程不值得
在討論恆星系統的適居性時停太久。
這些因素會在，比方說，恆星繞行星系時
穩不穩定、會不會撞上危險的恆星或星團。
這些因素會在，比方說，恆星繞行星系時
穩不穩定、會不會撞上危險的恆星或星團。
這些因素會在，比方說，恆星繞行星系時
穩不穩定、會不會撞上危險的恆星或星團。
我把它當作「小過濾」層級，
命名為「星系軌道的安全性」。
我把它當作「小過濾」層級，
命名為「星系軌道的安全性」。
還有很多恆星是雙星、多星，靠近到無法存在
穩定的行星軌道，這算做第四個小過濾，
又一個樂觀的高估。

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
Now another one that gets suggested a lot
is being hit by a supernova shock wave or
a dreaded gamma ray burst, but that needs
some quick context.
You need to be very close to one to get a
planet sterilizing event that can kill off
even deep ocean life and that won’t be too
common.
Nevertheless, if it kills off all large land
life, which would take a lot less impact,
you do get a substantial reset.
Yes lots of bacteria will survive, probably
even lots of insects, and certainly stuff
deep in the ocean unless we got really whammied,
but they will recover fairly quickly and let
evolution fill up the missing niches again.
Extinction events are hard to classify for
the Fermi Paradox though, that’s because
it’s hard to predict how common major or
near-total ones were even in Earth’s history,
let alone that of other solar systems in general.
Coupled to that, such events can often be
beneficial, clearing and leveling the Darwinian
battleground as it were.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
還有經常被強調的一點是，
不要被超新星、伽瑪射線爆打到，
但必須先講前提：
你要很靠近這些爆發才能完爆所有（甚至深海）生命，
這種情況不太常見，
你要很靠近這些爆發才能完爆所有（甚至深海）生命，
這種情況不太常見，
儘管如此，滅掉大型陸地生物，只要程度輕很多的爆炸
差不多就相當於砍掉重練—
很多細菌撐得過去沒錯，甚至很多昆蟲，以及
深海生物（必須很痛的爆炸才能消滅），
他們會很快恢復並讓演化再次填補生態空位。
深海生物（必須很痛的爆炸才能消滅），
他們會很快恢復並讓演化再次填補生態空位。
滅絕事件很難在費米悖論中歸類，
因為即使看地球歷史，
也很難預測大型、近乎全面滅絕事件的頻率
更不要說其他太陽系如何。
何況這類事件可能有益，用來清空、重設演化戰場
何況這類事件可能有益，用來清空、重設演化戰場

Chinese: 
也許恐龍完蛋，但若那顆小行星沒有撞上
恐怕也沒有今天的人類。
因此我總括外星滅絕事件：超新星、伽瑪射線爆、
小行星撞擊......概括成一次模糊的過濾，
這會是我們第一個「次過濾」級別。
提醒：通過「小過濾」機會在一半以上，
而「次過濾」是不到一半但還不到極小，
高於1％，我們今天就算10％，
這仍然是最樂觀的估計。
再來，不是每顆恆星都一模一樣，
我們稱太陽為「黃矮星」
但它其實算最大一類的恆星了。
它有如此稱號，殆因昔日只能觀測到最大最亮的恆星，
一如目前只能觀測到最大最熱的行星。

English: 
Dinosaurs were probably already on their way
out, but if that asteroid hadn’t hit, we
might not be here today.
So I am going to ball up all the various extraterrestrial
extinction causes – supernovae, gamma-ray-bursts,
asteroid bombardment, etc into one rather
nebulous filter and that one I will make our
first minor filter.
As a reminder, lesser filters were the kind
we thought lowered the odds to no worse than
a coin flip, while minor was anything that
most didn’t pass through but wasn’t terrible
odds, no lower than 1%, and for our final
calculation today I’ll treat it as 10%,
again we are using the favorable values.
Now not all Suns are the same, and while we
call our sun a yellow dwarf, it is actually
one of the most massive stars out there.
It got that misnomer because in early cataloging
we could only see the biggest and brightest
stars, just as now we can only see the biggest
and hottest exoplanets.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
Interestingly, the Sun is about as massive
as a star can be and still support life.
Stellar lifetime shortens exponentially with
a rise in mass, as its cube, so a star twice
our mass lives one-half-cubed, or one-eighth
as long.
So if our Sun was even 30% more massive it
would be just about ready to die by now.
To make things worse, since a star gets hotter
as time goes by, it’s habitable zone will
probably have shifted much more noticeably
during that time rendering some planets uninhabitable
that used to be habitable.
That is expected to happen here on Earth in
the next billion or so years, even if the
Sun’s main-sequence normal lifetime will
still have a few billions years left on the
clock.
This is not a good filter though, because
only a small percentage of stars are actually
massive enough to live so short a time.

Chinese: 
有趣的是，太陽幾乎是足以支持生命恆星的上限，
恆星質量會以質量的三次方縮短，
比太陽大兩倍的恆星，壽命僅八分之一。
恆星質量會以質量的三次方縮短，
比太陽大兩倍的恆星，壽命僅八分之一。
只要太陽比現在重30％，現在差不多就要死了。
更糟的是，恆星會隨著壽命逐漸變熱，
其適居帶將會更明顯遠離，
更糟的是，恆星會隨著壽命逐漸變熱，
其適居帶將會更明顯遠離，
曾經適居的行星將不再適居。
地球預計約十億年後將不再適居，
儘管太陽還會在「主序星」階段幾十億年。
地球預計約十億年後將不再適居，
儘管太陽還會在「主序星」階段幾十億年。
地球預計約十億年後將不再適居，
儘管太陽還會在「主序星」階段幾十億年。
但這也不是個嚴重的過濾，因為只有少數恆星
質量大到那麼短命。
但這也不是個嚴重的過濾，因為只有少數恆星
質量大到那麼短命。

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
這只適用在假設生命只於G型星旁生成。
我們太陽（G2級）即使在G型星中也算大的，
從0到9，G0最大G9最小。
我們太陽（G2級）即使在G型星中也算大的，
從0到9，G0最大G9最小。
恆星光譜有七大類，O, B, A, F, G, K和M，
只有K與M比G小，
但K型與M型星，兩者都比較大的五型星總數還多。
我們最關心的還是恆星的適居性，因為小恆星多，
最早還為此做了一集影片—但是我們並不管
我們最關心的還是恆星的適居性，因為小恆星多，
最早還為此做了一集影片—但是我們並不管
因為如前面所說，重點在「演化事件」的總數。
因為如前面所說，重點在「演化事件」的總數。
要產生文明之前，需要極多的演化事件，
那支影片的看法真的很黑歷史，

English: 
It matters only if we are assuming life is
limited to other G-type stars.
As a G2 star, our sun is fairly large even
for other G-types stars, that scale goes from
0 to 9, with 0 being largest and 9 smallest.
Of the seven classic Spectral Types, O, B,
A, F, G, K, and M, only K and M are smaller
than G but each of those groups has a higher
population than the other five combined.
The habitability of all those stars is therefore
of great interest to us, as they are way more
numerous, and we did one of earliest episodes
on that topic, BUT, we actually don’t care
about them for today's topic because of what
I mentioned earlier about total evolutionary
events.
For a civilization to emerge it needs a decently
high number of those total events.
It is a regrettably clumsy and ham-fisted
way to look at the issue and we’ll spend

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 

English: 
more time on it later in the series, but for
now we have to consider that if a planet is
tidally locked to a small red dwarf star,
as we have decent reason to think would tend
to be the case, that planet has a far smaller
habitable region to support life.
Less space, less life, therefore fewer evolutionary
events.
Again, we don’t care if they’ve got life,
we care if they’ve evolved into civilizations.
We also need to keep in mind that photosynthesis
on Earth does not use all of the sun’s spectrum,
and smaller stars emit even less light in
that photosynthetic range.
Less useful available energy, less life, more
of the material in that life devoted to basic
fuel gathering rather than other survival
tasks, and so on.
It doesn’t mean all those stars are uninhabited,
there’s a lot of question marks about tidal
locking, atmosphere slowing locking or being
torched away, solar activity being more erratic,

Chinese: 
這個系列之後會講到，但現在重點在行星圍繞紅矮星
可能導致「潮汐鎖定」，這就有足夠理由思考
那顆行星會只有一個很小的地區支持生命
更小的區域，更少的生命總量，更少的演化事件。
我們不管他生命何時產生，只管他們何時出現智慧文明
還要記得，地球上的光合作用，
沒有用盡所有電磁波頻段
更小的恆星釋放出更少的光以逕行更少的光合作用
更少的可用能源，則更少生命。
生命中有更大的比例在收集燃料
更少進行其他任務。諸如此類，餘下不表。
並不是說這些恆星都沒救，但還有一卡車關於
潮汐鎖定、侵蝕大氣層、大氣層被潮汐鎖定或被掀翻、恆星活動不穩定等問題，族繁不及備載。

English: 
and so on, but they aren’t good candidates
to produce civilizations and they make up
90% of the stars.
So I will give this one Minor Filter Status
too, though we will also attach to this category
things that make stars erratic in their output
as well, our sun is pretty stable compared
to most.
So we are at 4 lesser and 2 minor filters
so far.
How about planetary position?
Each star has a habitable zone, we roughly
classify that as any place where water is
a liquid, not too hot, not too cold.
That’s very debatable since you could have
moons around gas giants that were warm enough
by tidal heating for instance, but it is a
decently solid filter.
Not because such zones are rare, every star
has one, and we think most stars have planets
these days, so one being there isn’t too
improbable.
However we have to consider three important
factors on this.
First, what are the odds that planet is about
as massive as Earth?

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
但是以產生文明來講，它們並是不夠格的候選，卻又包含90％的恆星。
但是以產生文明來講，它們並是不夠格的候選，卻又包含90％的恆星。
我真的要給他「次過濾」等級，這層過濾包括
使恆星輸出不穩定問題，我們太陽相形之下就很穩定。
使恆星輸出不穩定問題，我們太陽相形之下就很穩定。
現已累積4個小過濾和2個次過濾。
行星的位置呢？
每個恆星周圍都有「適居區」，
我們大概以液態水能存在為準
不能太熱、不能太冷。
這有許多爭議，因為氣體巨行星的衛星，可以透過
潮汐力等作用加熱，在適居區外擁有液態水
但這是一到如假包換的過濾。
不是因為適居帶很稀有（每個恆星都有），
且現在我們認為多數恆星有其行星，
行星位於適居帶似乎不會太稀奇
不過我們要考量三大因素：
一、這顆行星的質量是否接近地球？

Chinese: 
渺小的火星蹲在適居帶沒用，
它小到不足以撐起大氣層數十億年。
渺小的火星蹲在適居帶沒用，
它小到不足以撐起大氣層數十億年。
木星這種氣體巨行星蹲在適居帶也沒用，
氣態的表面要怎麼長生命—
至少生不出智慧生命。不過大型的衛星可能可以。
後者似乎機率渺茫，因為太陽系中
沒有哪個衛星堪與地球較量。
後者似乎機率渺茫，因為太陽系中
沒有哪個衛星堪與地球較量。
甘尼美德（木衛三）是最大的，
其實體積比水星大（質量卻較小），
表面上的重力也才地球的15％
所以我們要考慮那些接近地球大小的衛星，
但要多接近也難說。
所以我們要考慮那些接近地球大小的衛星，
但要多接近也難說。
我說三件事的第二、行星必須持續待在適居帶。
大部分行星軌道不會是正圓，
地球軌道離心率算低（很圓），
金星更低，而水星最高。

English: 
Doesn’t matter if some tiny planet like
Mars is there, it could never hold an atmosphere
that close to the Sun for billions of years.
Doesn’t matter if a big planet like Jupiter
is there, no life is evolving on a gas giant,
not to technological civilizations anyway,
although maybe a large moon around one might.
That last wouldn’t seem too probable though
since no moon in our solar system is even
close to being as massive as Earth.
Ganymede is the biggest, actually larger than
Mercury though less massive, and has a surface
gravity that’s only 15% of Earth’s.
So we have to consider that it needs to be
a planet decently close to Earth’s own size,
though how close is hard to say.
I said three things though and the second
would be that it needs to be staying inside
that habitable zone, most planets don’t
have circular orbits, Earth has one of the
lowest orbital eccentricities, Venus lower
still, while Mercury has the highest.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
很可能這些適居帶過於高估，其邊緣已經不適合居住，
加上橢圓軌道更慘。
很可能這些適居帶過於高估，其邊緣已經不適合居住，
加上橢圓軌道更慘。
很可能這些適居帶過於高估，其邊緣已經不適合居住，
加上橢圓軌道更慘。
當然即使一個系統中有行星軌道「接近」適居帶，
就會（重力干涉）使其他行星無法穩坐適居帶。
我算他「小過濾5」，
「太陽系生成時，不得有其他天體佔據適居帶」
第六個小過濾，
我要總括行星被踢出軌道、被其他天體捕捉、
被轟出太陽系或被轟向太陽的可能性。
行星的軌道不若你想像中穩定，太陽系剛誕生時，
行星的數量和軌道很可能遠遠不是今天這樣。
行星的軌道不若你想像中穩定，太陽系剛誕生時，
行星的數量和軌道很可能遠遠不是今天這樣。
行星的軌道不若你想像中穩定，太陽系剛誕生時，
行星的數量和軌道很可能遠遠不是今天這樣。
特別是至少一次，地球被另一個行星迎頭撞上，
流行的學說還認為同樣巨大的撞擊導致金星
緩慢的自轉，使金星一天比一年還長。
流行的學說還認為同樣巨大的撞擊導致金星
緩慢的自轉，使金星一天比一年還長。

English: 
Odds are pretty good that the official habitable
zones are already too generous and those near
the edges won’t be hospitable for life,
if you add eccentricity into that it gets
worse.
And of course even if a system has a habitable
zone with planets near it, there might not
be one actually in it, so we’ll make that
Lesser Filter 5, no planet of any sort happens
to occupy the habitable zone, when the system
forms.
For #6, we’ll include the chance that the
planet gets itself knocked out of orbit or
captured or ejected out of the system or into
the Sun.
Orbits aren’t nearly as stable as we often
think; odds are better than good that not
all of the planets we started out with in
our solar system are still here and probably
aren’t all quite where they began.
Indeed, it seems likely that at least one
time Earth got smacked by one, and it’s
also a pretty popular theory that one nailed
Venus causing its peculiarly slow spin, thus
having a day longer than its year.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
Systems with more planets would probably be
even more vulnerable to such things, especially
if they had big planets closer in.
The mass of a planet in the habitable zone,
if we have one, matters a lot.
We do not have a good inventory of planets
yet to say what percentage of them are of
any certain size, but we have started finding
a lot of Super-Earths out there in habitable
zones or closer so we know there’s no special
barrier against their existing.
In between things like Mercury and Jupiter
is a mass difference of about 1000... and
you could go bigger or smaller and still have
that habitable zone dominated by that planet
so no others could be there.
We can’t assume planets are evenly distributed
by mass, that there’s as many planets twice
the size of Earth as there are half the size
or ten times the size.
Indeed, what we do know suggests otherwise,
but if we did assume that for the moment,

Chinese: 
更多行星的系統恐怕更脆弱，
尤其是在巨行星靠很近的時候。
更多行星的系統恐怕更脆弱，
尤其是在巨行星靠很近的時候。
適居帶內的這顆行星（如果有的話）質量很重要。
我們沒有足夠的行星資料，看說某個質量的行星佔幾％
但我們開始發現許多適居帶甚至更內側的「超級地球」
由此可知沒有什麼障礙阻止它們形成。
但我們開始發現許多適居帶甚至更內側的「超級地球」
由此可知沒有什麼障礙阻止它們形成。
水星和木星之間，質量差了約一千倍......
行星還能更大或更小，繞行適居帶而其他行星不得靠近
行星還能更大或更小，繞行適居帶而其他行星不得靠近
不能假設行星質量是均勻分佈的—
像是兩倍地球質量的行星
不一定和一半、十倍地球質量的行星一樣多。
據我們所知事實相反，但如果我們先接受上述假設，

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
then we have a Major Filter right there, because
of possible planets -- from dwarf planet’s
just big enough to dominate their orbit to
super-Jovians nearly big enough to count as
a star - only a tiny range of those could
plausibly support the kind of life we’re
interested in even if we are stretching plausibility.
We’ll give this one Minor Filter Status,
our third, though it would not be hard to
argue it was a Major Filter all on it own...
we just don’t know and where there is uncertainty,
we will err on the side of generosity today.
So 3 minor and 6 lesser.
I’m going to bypass our day length and axial
tilt because those are very dependent on our
moon, arguably so is our crustal composition
since the Moon formed when we got whacked
by some other planet, or rather when two planets
smacked each other to form our current one
and the moon.
For a long time we thought the Moon itself
such an anomaly that it might be a great filter
all by itself, but newer models say that such
giant moons might not be so uncommon after

Chinese: 
一個「主過濾」就砸過來了，因為在所有行星中，
從勉強能夠清空軌道的矮行星，
到幾乎算是恆星的「超級木星」，
只有一小部份可能支持我們在找的那種生命，
儘管我們的標準還只是「可能性」。
只有一小部份可能支持我們在找的那種生命，
儘管我們的標準還只是「可能性」。
我還是將其歸類為「次過濾」級別，
儘管要說他到達「主過濾」標準
亦難以反駁。我們不知道準確數據。
但凡今天有不確定的，我們全部樂觀估計下去。
亦難以反駁。我們不知道準確數據。
但凡今天有不確定的，我們全部樂觀估計下去。
3個次過濾，6個小過濾。
我要講到晝夜長和地軸傾斜角度，
因為受到月球影響甚多，
也許連地殼組成也是，畢竟月球是在地球被
另一顆行星當頭巴下，或是兩個行星對撞才產生的。
另一顆行星當頭巴下，或是兩個行星對撞才產生的。
長期以來我們認為以月球之奇特，可能即是大過濾
但新模型表示大型的月球似乎觸目皆是。

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
但新模型表示大型的月球似乎觸目皆是。
不尋常或破天荒，
我們的巨大月球對於包括行星穩定、適居性
等各種因素有全面影響，可同時那些因素似乎只是
錦上添花，沒有月球的類地行星並非完蛋，
雖然整體看我該把月球列到「主過濾」，
但還是先放在「次過濾」欄位。
雖然整體看我該把月球列到「主過濾」，
但還是先放在「次過濾」欄位。
我們曾經認為月球是關鍵，但舉個例子說
生命可能起源於潮池，而月亮主宰潮汐。可是太陽
也能掀起較低的潮汐；
況且現在更傾向生命起源於海底熱泉的說法，
因此我覺得需要儘量樂觀的給他「次過濾」。
說到海底熱泉，地球的板塊運動和融化的核心
對於提供磁場保護和板塊運動的持續至關重要，

English: 
all.
Uncommon or ultra-rare, our big moon is a
huge factor in all sorts of things that make
our planet stable and livable, yet at the
same time many of these factors just seem
to better the odds for life not really exclude
it for Earth-like planets without a moon,
so while we should probably still list the
Moon as a major Filter overall, I will keep
it at Minor filter status.
We used to be sure the Moon was a key factor,
as I said, but one of the examples for that
is that life began in tidal pools, and the
Moon dominates those, but the sun alone causes
decent tides and we also tend to tilt more
to expecting life to have emerged around underwater
thermal vents, so I feel we should hedge our
bets and say Minor.
Speaking of those thermal vents, our planet’s
tectonic activity and molten core are hugely
important both towards providing us with a
protective magnetosphere, as well as ensuring

English: 
plate tectonics that both give us thermal
vents and help create a geological cycle that
replenishes elements on the surface and ensures
there is surface land that hasn’t been eroded
away, making the planet all one big sea.
Yet while such activity is vitally important,
and probably less common on smaller planets
for instance, we’ve already excluded those
and we don’t have too much reason to think
there’s a very narrow zone of these permissible
that most Earth-sized planets would lack.
These are both very big factors though.
A planet’s magnetosphere controls whether
or not it can keep an atmosphere in the long
term, and the spin rate of planet effects
that, while at the same time, the faster a
planet spins, the stronger the erosive winds
and storms trying to erode away the land.
Too much tectonic activity could be devastating,
indeed, considering how many cities were ruined
by Earthquakes in the past, if those were
stronger and more common folks might never

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

Chinese: 
板塊運動給了我們熱泉，
並創造出補充地表元素-抵銷地表侵蝕的地質循環，
板塊運動給了我們熱泉，
並創造出補充地表元素-抵銷地表侵蝕的地質循環，
讓我們星球不至於淪為一片平坦的汪洋。
雖然地質活動極為重要，在更小的行星上更難見到，
我們直接排除他們，而且不須太多理由足以認定
地質活動的門檻很窄，大多數類地行星都缺乏，
但這些都是重要因素。
行星磁場會決定是否能長期保有大氣層，
但行星的轉速也同時影響，
自轉越快，侵蝕地表的風暴就更強。
但行星的轉速也同時影響，
自轉越快，侵蝕地表的風暴就更強。
太強的板塊運動則導致毀滅，想想有多少城市
被地震震垮，而那些地質更活躍的星球上

Chinese: 
可能永遠無法建造城市......但板塊運動太少將或
沒有足夠陸地，
或沒有地質活動把礦物質帶上來並儘早累積氧氣。
沒有足夠陸地，
或沒有地質活動把礦物質帶上來並儘早累積氧氣。
不確定因素太多，
我們會警戒地把這兩個加入「小過濾」級
這樣就有8個小過濾和4個次過濾
還有很多能檢視的，又有許多已經被我們統合成組了。
還有很多能檢視的，又有許多已經被我們統合成組了。
接下來還有重重難關，
今天只著重於對行星組成、位置有影響者—
那些最核心的地球殊異過濾，
但今天的重頭戲就是加成，來吧。
那些最核心的地球殊異過濾，
但今天的重頭戲就是加成，來吧。
還記得我們把「大過濾」定義為幾乎不可能跨越，
存活率百萬分之一、甚至更低。
還記得我們把「大過濾」定義為幾乎不可能跨越，
存活率百萬分之一、甚至更低。
我們還說今天加總時，
會把「小過濾」當50％而「次過濾」當成10％。
我們還說今天加總時，
會把「小過濾」當50％而「次過濾」當成10％。

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
settle down to build cities… and yet too
little of such activity and you won’t have
land masses or the geological pump that brings
up new minerals and helps sequester oxygen
early on.
Too many uncertainties, so again we’ll be
cautious and call each just a lesser filter,
placing us at 8 lesser and 4 minor.
There are so many others we could look at,
and many we’ve shoved together into broader
filters.
There are many more still to come too, we’ve
just looked at those which are characteristic
of our planet’s composition and position,
the core Rare Earth filters, but that was
our focus for today so let’s total them
up.
Remember that we classified a Great Filter
as something virtually none passed, one in
a million at best and often worse.
We also said that for our totaling today we
would treat a lesser filter as 50/50 and a
minor one as 1 in 10.

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
Many of them we looked at today were probably
way worse odds than that, but let’s see
how we come out with 8 lesser filters and
4 minor ones.
Cumulative odds can just be multiplied together,
the odds of flipping a coin heads is 1 in
2, the odds of doing so twice in row, one
half times one half, or 1 in 4, three times
1 in 8.
So our 8 lesser filters are 1 in 2^8, or 1
in 256.
Not bad, our 4 minor filters, 1 in 10, are
worse, 1 in 10^4, or 1 in 10,000.
Combined together they equal 1 in 2,560,000.
Less than 1 in a million, so we establish
a good case for the conditions on Earth to
be a Great Filter.
Incidentally if we treated those 4 minor filters
as just 1%, our lower end value for minor
filters, it would be 1 in 2,560,000,000, not
a million.

Chinese: 
今天講到很多因素可能遠遠更加險阻，
但是我們先這樣算，8個小過濾和4個次過濾
今天講到很多因素可能遠遠更加險阻，
但是我們先這樣算，8個小過濾和4個次過濾
累積的事件乘起來算：丟一面銅板正面的機率是1/2
丟兩遍是1/4，丟三遍是1/8，以此類推。
丟兩遍是1/4，丟三遍是1/8，以此類推。
所以8個小過濾是1/2^8或說1/256。
不錯，我們四個次過濾更慘些，1/10^4或萬分之一。
兩者乘起來1/2,560,000。
比百萬分之一還小，我們有充分證據指出，
「生成地球這樣的行星」就是個大過濾。
比百萬分之一還小，我們有充分證據指出，
「生成地球這樣的行星」就是個大過濾。
若以低標估計，4個次過濾都僅1％機會存活，
則總結1/2,560,000,000，刷新下限。
若以低標估計，4個次過濾都僅1％機會存活，
則總結1/2,560,000,000，刷新下限。

Chinese: 
但是我們的目標只是確認這是大過濾無誤，
並不是最悲觀估計。
即使這個機率，本銀河細中仍有一百多顆適居行星
比較樂觀的版本則允許數十萬顆。
但它確實嚴重降低文明興起繁盛的機率。
有些人就此打住，的確我們很多「小過濾」
都可能上升到「次過濾」等級，
在此情況機率壓低到一個星系不到一顆行星，
但我覺得雖不中亦不遠矣，
後頭還有發展智慧與科技的過濾在等著壓低生存率。
後頭還有發展智慧與科技的過濾在等著壓低生存率。
這些數值都相當不確定，原因是真的沒有太多能斷言。
這些數值都相當不確定，原因是真的沒有太多能斷言。
但這大概是費米悖論—地球殊異假說的機率，正如所見

English: 
But, our goal was just to show that it qualified
as a Great Filter, not the worst case scenario.
Even that value though would still leave a
hundred planets in our galaxy with those conditions,
and our more moderate value would allow for
a hundred thousand.
But it does seriously lower the odds for civilizations
to emerge and flourish.
Some folks stop here, indeed many of the filters
we used could easily be boosted to Minor Filter
status, not Lesser, and in doing so would
smash the odds down to a lot less than one
such planet a galaxy, but for my part I tend
to think we are in about the right zone with
our figures, and that it’s the filters that
come after this in developing intelligence
and technology that help sweep the odds further
down.
There’s so much uncertainty to all these
values, and the reasoning behind them, that
we just can’t say much for sure.
But this is the basis of the Rare Earth Solution
to the Fermi Paradox, and as you can see,

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
it makes a pretty good case for Earth-like
planets that can foster technological civilizations
to be quite uncommon and possibly so rare
that you won’t find another one even in
the entire galaxy.
Next time in this series we will look at the
biological side of things in more detail and
see how all those factors can stack up to
form yet another Great Filter, but before
that we will be discussing some other topics,
and in next week’s episode we’ll examine
the popular science fiction concept of force
fields and see if there’s any room for that
to become science reality, not science fiction,
and also discuss some of the fun things you
could do with them if you had them.
For alerts when those episodes come out, make
sure to subscribe to the channel, and if you
enjoyed this episode, hit the like button
and share it with others.
If you want to discuss this topic some more,
head down to the comments section below or
join the over 10,000 members on our facebook
group, Science and Futurism with Isaac Arthur.

Chinese: 
很可能類似地球這樣，能發展科技文明的行星
極為少數，在整個銀河系中找不出第二個。
很可能類似地球這樣，能發展科技文明的行星
極為少數，在整個銀河系中找不出第二個。
很可能類似地球這樣，能發展科技文明的行星
極為少數，在整個銀河系中找不出第二個。
本系列下集將著重探討生物性因素，
並看那些因素能再加成出一個大過濾，但在此前
我們會先討論別的主題，下週會說到
「力場」這個科幻常見的概念，檢視能否實現，
在現實而非科幻中。
也會討論一些用力場就能做到的趣事。
在現實而非科幻中。
也會討論一些用力場就能做到的趣事。
記得開小鈴鐺家訂閱，
若你喜歡本集，請按讚並分享。
若想繼續討論此主題，請至下方留言
或加入超過一萬人的臉書社團，Science and Futurism with Isaac Arthur。

Portuguese: 
 
 
 
 
 
 
 
 
 
 
 
 
 

English: 
Until next time, thanks for watching, and
have a great week!

Chinese: 
感謝收看下回見，祝您美好的一週～

Portuguese: 
 
