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00:00 What scares you the most about science?
00:03 Is there any one theory or prediction that really keeps you up at night?
00:06 And have you ever wondered whether actually there are some problems out there that truly
00:10 could ruin everything?
00:11 In our new series, we strive to analyse the biggest and most significant unknowns surrounding
00:16 the key issues of science, technology, life, and everything.
00:22 This is Unveiled, and today we're taking a closer look at thirteen disturbing paradoxes
00:27 that even scientists are terrified by.
00:30 Do you need the big questions answered?
00:31 Are you constantly curious?
00:33 Then why not subscribe to Unveiled for more clips like this one?
00:36 And ring the bell for more thought-provoking content!
00:39 The Fermi Paradox
00:40 Let's start with one of the biggest and most all-encompassing.
00:44 Thanks largely to science fiction, the Fermi Paradox has infiltrated into the mainstream
00:49 in recent times, but that hasn't done much to dilute the more ominous implications that
00:53 it carries in the real world.
00:55 In simple terms, it's a thought experiment that questions the apparent contradiction
00:59 between the vastness of the universe and the lack of evidence of extraterrestrial life.
01:04 It was first posed by the influential 20th century physicist Enrico Fermi in 1950.
01:10 Legend has it, during an otherwise quite casual lunchtime conversation with his colleagues
01:13 at the time, we can think of the paradox as being based on several assumptions.
01:18 First, the universe is billions of years old, giving ample time for life to evolve.
01:23 Second, stars are abundant, providing countless potential sites for life-bearing planets.
01:28 Third, technology can advance over time, enabling civilizations to travel through space.
01:34 With all of these things in mind, however, and as Fermi himself is said to have momentously
01:38 exclaimed, "Where is everybody?", why isn't the universe teeming with alien life, when
01:43 all the markers suggest that it should be?
01:45 As such, and in the years since, the Fermi Paradox has given rise to a number of potential
01:50 solutions, some of which are pretty scary.
01:53 First there's the Zoo Hypothesis, suggesting that advanced civilizations are actively observing
01:58 our planet, but that they deliberately refrain from making contact… all to prevent us from
02:04 developing too quickly or interfering with their plan.
02:07 In this sense, alien life is all around, it's just that we're inescapably caged by it.
02:12 An extension of the Zoo Hypothesis, the Lab Hypothesis, takes it one stage further, too,
02:18 suggesting that not only are we being watched all the time, but we're also being experimented
02:23 on by those that are watching.
02:25 Next there's the Rare Earth Hypothesis.
02:27 This theory claims that Earth's unique combination of conditions is exceptionally favourable for
02:33 life, and therefore the vast majority of other planets may not be capable of supporting complex
02:38 organisms.
02:39 On the face of it, this perhaps isn't quite so frightening as us all unknowingly swimming
02:43 around in an alien petri dish… but many scientists are at least concerned by the potential
02:48 for Rare Earth.
02:50 If true, it would mean that we are entirely at the mercy of our unlikely circumstances,
02:55 that we'll probably never be able to move away from Earth, and that we are therefore
02:58 doomed to extinction one day, no matter what we do.
03:02 And finally, there's the relationship between the Fermi Paradox and the Great Filter.
03:06 Generally, the Great Filter suggests that there are various, insurmountable obstacles
03:11 that prevent most civilizations from reaching advanced technological levels.
03:15 These obstacles could include cosmic disasters, resource depletion, or self-destruction.
03:21 And ultimately, that's why the universe apparently isn't full of life.
03:25 We must then consider whether humans have passed through the Great Filter, or whether
03:29 it still lies ahead for us… and statistically, the chances are slim for the former.
03:33 What's much more likely is that the Fermi Paradox proves that the Great Filter lies
03:38 ahead, and that we're all inevitably doomed as a result.
03:46 The Grandfather Paradox In general, time travel is easily one of
03:50 the first ports of call whenever paradoxes are on the table.
03:54 There's just so much that can go wrong.
03:56 There's just a lot of weirdness whenever the potential to bend and shape time is considered.
04:01 But still, the Grandfather Paradox is one of the best known, and one of the most dangerous.
04:06 In short, it asks, what would happen if time travel were possible, and you travelled back
04:11 in time and did something to prevent your own existence?
04:14 Such as killing your grandfather before your parent was conceived?
04:18 The problem being that, if you did that, then you wouldn't be able to travel back in time
04:23 to kill your grandfather in the first place.
04:26 Because you don't exist, all of the above will have effectively erased itself.
04:30 It's a logical contradiction, a clear inconsistency within the idea of cause and effect, which
04:36 is otherwise vital to how we understand the universe.
04:39 The term "Grandfather Paradox" doesn't have a clear origin, but was popularised in
04:43 science fiction and general discussion about the implications of time travel, dating back
04:47 to at least the early twentieth century.
04:50 There have been a number of proposed solutions put forward, although one in particular is
04:54 somewhat worrying.
04:55 It could be that any action taken by a time traveller would be a part of history all along…
05:01 which means you could never change events to prevent your birth because any attempt
05:04 would fail, or cause an alternate series of events leading up to your existence regardless.
05:09 It's probably the neatest way out of the problem, but it also implies a wholly deterministic
05:14 universe where free will doesn't exist, and any semblance of choice is an illusion.
05:19 Of course, right now, time travel doesn't exist, so perhaps it isn't worth fretting
05:24 over.
05:25 However, the profound philosophical questions are still pushed front and centre, simply
05:29 due to the fact that the paradox can be thought up.
05:33 We can ask ourselves, "Is every moment predestined?"
05:36 Are we ever truly in control of our actions, or even our thoughts?
05:41 And naturally, should we really be trying, or even hoping, to travel in time at all?
05:53 The Cobra Effect Otherwise known as a "perverse incentive",
05:57 the Cobra Effect is traditionally related to the science of economics, although its
06:01 implications are wide.
06:03 And ultimately, it's due to it being a seemingly universal rule as to why it can often feel
06:07 a little unsettling.
06:09 The Cobra Effect is a term used to describe an unintended outcome that is the opposite
06:14 of the intended outcome.
06:15 It occurs when an incentive created to solve a problem ends up exacerbating the very issue
06:21 due to unforeseen circumstances.
06:23 The phrase is said to refer to an historical incident during British rule in India.
06:28 So the story goes, to reduce the number of venomous cobras, authorities at the time offered
06:33 a bounty for every dead snake brought in by citizens.
06:36 At first, it worked.
06:38 But then it led to an increase in the cobra population.
06:41 Why?
06:42 Because people began to breed cobras in order to collect the bounty.
06:46 Finally, when this was discovered and the reward was ended, the impromptu cobra breeders
06:50 released their now worthless snakes into the wild, meaning that at the close, there were
06:55 actually more snakes than ever.
06:57 The effect isn't just about snakes, though.
06:59 It represents any situation where interventions have almost inescapably negative outcomes.
07:05 As well as economics, it's rooted in behavioural psychology, especially highlighting humankind's
07:10 habit for social short-sightedness.
07:13 As a paradox, it challenges, even rubbishes, the belief that well-intentioned policies
07:18 will always have positive outcomes.
07:20 Arguably the most pervasive real-world example is the modern phenomenon of antibiotic resistance.
07:27 Ever since they were introduced, antibiotics have proven essential for treating infections.
07:32 But today, their overuse has led to the emergence of antibiotic-resistant bacteria, rendering
07:37 once life-saving drugs increasingly ineffective.
07:41 We also face similar dilemmas with the emergence of artificial intelligence, where algorithms
07:46 designed for good might perversely optimise for harmful outcomes.
07:50 Elsewhere, analysts worry about how cash injections can eventually distort markets.
07:56 Environmentalists ponder if conservation efforts could actually harm ecosystems.
08:01 Public health officials debate whether certain campaigns inadvertently promote risky behaviour.
08:06 Overall, the Cobra Effect shows our always-limited ability to accurately predict what will happen
08:12 in a complex system.
08:13 It warns us that even the most well-meaning actions can have dire results if we don't
08:18 fully understand every aspect they touch upon.
08:21 All in all, it's a seeming fact of life that can leave you feeling quite powerless.
08:31 The Bootstrap Paradox For our second and last time-travel-specific
08:36 phenomenon, the Bootstrap Paradox has proven a head-scratcher of the highest order for
08:40 decades.
08:41 The term perhaps came to prominence following the publication of sci-fi writer Robert A.
08:45 Heinlein's 1941 short story "By His Bootstraps".
08:50 In it, a man travels back in time, and gives himself the knowledge necessary to invent
08:54 the time machine he used to travel back in time.
08:57 More broadly, the paradox also takes its name from the expression "to pull oneself up
09:02 by one's bootstraps", implying a self-contained process and usually an impossible action.
09:08 In general, then, the paradox refers to any situation where an object or piece of information
09:13 is sent back in time and becomes trapped in an infinite cause-and-effect loop, wherein
09:18 it has no discernible origin.
09:21 Imagine someone travels back in time with a scientific paper containing groundbreaking
09:26 equations.
09:27 They give this paper to a young scientist, who then publishes these findings as their
09:30 own work.
09:31 As time progresses, the equations become famous… until another person decides to take them
09:36 back in time again, repeating the cycle endlessly.
09:40 Where did those equations originally come from if they were never independently created?
09:44 Similarly, consider going back in time and giving William Shakespeare a copy of Hamlet
09:49 before he writes it.
09:50 Where did Hamlet originate?
09:52 Or taking a wheel back to the Stone Age?
09:54 How was the wheel invented?
09:56 While closely related to other temporal paradoxes like the Grandfather Paradox, the bootstrap
10:01 problem focuses specifically on informational or physical anomalies, rather than changes
10:06 to timelines.
10:07 On the one hand, it arguably suggests that time travel will never be possible, because
10:12 such informational headaches should be all around us, if it were.
10:16 But on the other hand, could it imply not only that time travel is possible, but that
10:21 we're all hopelessly trapped within the fixed parameters of it, by default?
10:25 It's an idea that challenges foundational principles.
10:28 The very nature of science relies on traceable chains of evidence and causation.
10:33 An uncaused event simply doesn't fit, and that's enough to leave even the smartest
10:37 of us at a complete loss.
10:39 Mortality is home entertainment!
10:41 This cannot be the future!
10:44 Infinite Divisibility The notion of infinity is easily one of the
10:47 most fascinating in all of science and philosophy.
10:51 But depending on how you look at it, it can either prove a source of immeasurable wonder,
10:55 or it can send you spiraling into never-ending despair.
10:59 In general, infinite divisibility is the seeming paradox that suggests an object could be divided
11:04 in half an infinite number of times without ever reaching an indivisible limit.
11:09 Theoretically, it shouldn't even matter if there really was a bottom-most unit for
11:13 whatever it was you were dividing into two.
11:15 The divider should still be able to half and half and half again, forever.
11:20 It ties back to ancient Greece, with what have come to be known as Zeno's Paradoxes.
11:25 The most famous one, Achilles and the Tortoise, tells us about a race where the swift Achilles
11:30 gives a tortoise a head start.
11:32 But, although Achilles runs much faster, by the time he reaches where the tortoise was,
11:37 it has moved forward slightly.
11:39 According to Zeno's reasoning, since there are infinitely many points Achilles must reach
11:43 where the tortoise has been before overtaking it, he can never actually pass it.
11:49 This introduces the idea that space could be infinitely divisible, while at the same
11:53 time remaining logically absurd.
11:56 More practically, it's something that collides with the principles of quantum mechanics.
12:01 Atoms were once thought to be indivisible, hence their name derived from "atomos",
12:05 which means "uncuttable".
12:06 But of course, now we know that actually they consist of smaller particles like protons
12:10 and electrons.
12:12 We then know of further subatomic entities, like quarks and leptons.
12:16 But could we, due to infinite divisibility, keep going?
12:20 Some believe that there must be fundamental limits, such as the Planck length, beyond
12:24 which space-time really doesn't have any physical meaning and cannot be further divided.
12:30 But that's also a logical stumbling block, because again, logically, something can always
12:35 be halved.
12:36 Mathematically speaking, numbers certainly are infinitely divisible.
12:40 You can always find another fraction between two numbers, no matter how close they are
12:44 together.
12:45 But the fact is that when that's applied to physical reality, such as for distance, matter,
12:49 or even for time, it becomes troublesome.
12:52 Troublesome to the point that, somewhat ironically, no one could ever spend quite enough time
12:57 trying to work it all out.
12:59 "Whoa, this is heavy."
13:00 "There's that word again, heavy.
13:03 Why are things so heavy in the future?
13:04 Is there a problem with the Earth's gravitational pull?"
13:06 Hilbert's Hotel.
13:08 At the other end of the scale to infinite divisibility, there's Hilbert's Hotel.
13:13 This is an imagined hotel with an infinite number of rooms.
13:17 Such a place should always have space for new guests, but at the same time could reasonably
13:22 be described as being always full.
13:24 On the one hand, every room is occupied.
13:27 On the other, the hotel can still accommodate more travellers, which is mind-bending even
13:31 to begin with, but it goes deeper still.
13:34 Consider the role of Hilbert's Hotel manager.
13:37 Their establishment is already infinitely full, but someone new arrives.
13:41 They can accommodate them by quite simply asking everyone who's already staying at
13:45 the hotel to move one room along.
13:47 Room one moves to room two, room two moves to three, and so on, forever.
13:52 The new guest takes the newly vacant room one.
13:55 Even though it seems like there should be no space left, there always will be an infinite
13:59 amount of space to offer.
14:01 The hotel wouldn't even buckle if an infinite number of guests turned up at its door.
14:06 Or an infinite number of planes flew in, carrying an infinite number of guests who all needed
14:10 a room.
14:11 Or an infinite number of planes flew into an infinite number of airports, and so on.
14:16 This particular representation is attributed to one David Hilbert, a German mathematician,
14:21 who's said to have first voiced it in the mid-1920s.
14:24 But there are a number of other, similar models, including Borges' Infinite Library, created
14:30 by the Argentine writer Jorge Luis Borges for his 1941 short story, "The Library of
14:35 Babel".
14:36 This is an endless world filled with books containing every possible combination of letters.
14:41 In practice, this means that the library houses an infinite amount of knowledge, and gibberish
14:46 alike.
14:47 Open any book, and you might well find whatever's written in it to be indecipherable.
14:51 But equally, you might find one word that makes sense, or one sentence, one paragraph.
14:57 And ultimately, in amongst all of the nonsense, there should also inevitably be every possible
15:03 arrangement of letters to convey meaning.
15:05 There will even be many, technically infinite works of literary genius.
15:10 One other way of approaching this is via what's known as the "Infinite Monkey Theorem",
15:14 which suggests that given an infinite number of monkeys hitting keys at random on typewriters
15:19 over the course of an infinite amount of time, they will almost surely type out any given
15:25 text, even the complete works of Shakespeare.
15:27 As fun as all this is to contemplate, however, it's also cause for some to lose sleep.
15:32 Returning to Hilbert's Hotel, and if it never stops, then what does that say about
15:37 the so-called fundamentals of physics?
15:39 For example, the total energy required to run the hotel would also be infinite, therefore
15:45 violating the laws of thermodynamics.
15:47 What's more, the process of organising an infinite number of guests requires an infinite
15:52 amount of time and resources.
15:54 But can any computational process handle that in reality?
15:58 Even in terms of pure space?
16:01 And even if the universe were proven beyond a doubt to be infinite, in itself, then could
16:06 there ever be enough space to accommodate Hilbert's Hotel?
16:10 Which infinity wins out?
16:11 How is anything ever resolved if it simply carries on, and on, and on?
16:18 "So when did the old place get a facelift?"
16:21 "Around four years ago.
16:23 But I assure you, sir, she really hasn't changed much."
16:26 The Twin Paradox
16:28 Whenever there's talk of paradoxes, it isn't long before one Albert Einstein is mentioned.
16:33 And here's where possibly the most famous scientist of all time really enters the fray,
16:37 thanks to a thought experiment and physical reality that's all tied up with his theories
16:42 of special relativity.
16:43 Picture identical twins, Bob and Alice.
16:47 Bob stays on Earth, while Alice travels on a spaceship to a distant star and back again.
16:52 According to the theory of special relativity, time dilation occurs for objects in motion
16:57 relative to an observer.
16:59 Time isn't absolute, but relative.
17:01 It can pass at different rates for different observers depending on their relative speeds.
17:06 In the context of the fate of our twins, this ultimately means that time passes slower for
17:11 Alice on her spaceship (which is perhaps approaching light speed) than it does for Bob on Earth.
17:17 From Bob's perspective, Alice's journey to wherever it is she's going could take
17:21 many years.
17:22 However, from Alice's perspective, zooming through space (although still apparently ageing
17:27 at the same rate) it's a journey that's taken much less time when she returns to Earth,
17:33 due to time dilation.
17:35 Therefore, when Alice arrives back, she's younger than Bob, despite being the same age
17:40 when they parted ways.
17:42 In extreme cases, the space-faring twin may even have missed the entirety of their sibling's
17:47 life… decades of real-time experiences, despite themselves feeling as though they've
17:52 only been away for a short time.
17:54 While this perhaps isn't a paradox with any immediately terrifying practical implications,
17:59 it is still something that can feel deeply unsettling.
18:02 It can evoke existential unease, because it shows that our most basic understanding of
18:06 reality, time itself, isn't universally consistent.
18:10 It doesn't flow the same for everyone or everything… which is something like having
18:14 the cosmic rug suddenly pulled from under your feet.
18:17 Of course, there are some implications for space travel, too.
18:21 The twin paradox raises questions about the effects of long-duration space travel on astronauts.
18:26 Technologically speaking, we are still a long way from this stage… but if humans ever
18:31 were capable of moving between stars, then the effects of time dilation could very quickly
18:36 ruin any sense of a link or continuity from one world to another.
18:41 It's one way in particular that our species would intrinsically change if we ever did
18:46 launch off Earth for good.
18:47 "There ought to be something very special about the boundary conditions of the universe.
18:54 And what can be more special than that there is no boundary?"
18:59 Schrodinger's Cat
19:01 Along with the Fermi Paradox, Schrodinger's Cat is a prime example of a complex, theoretical
19:06 concept that has really caught on in the wider world.
19:09 It's another that science fiction loves to delve into… and by now it's a well-known
19:13 setup.
19:14 But let's recap.
19:15 First we have our cat.
19:16 But then the cat is placed in a sealed box along with a radioactive atom.
19:20 The atom has a fifty percent chance of decaying within an hour, triggering a mechanism that
19:25 will release poison and kill the cat.
19:27 But here's the thing.
19:28 According to quantum mechanics, until the box is opened and the state of the atom is
19:32 observed, the atom exists in a superposition of states.
19:36 This means that it's both decayed and not decayed at the same time.
19:40 And as a result, the cat is also in a superposition of states.
19:44 It's both alive and dead simultaneously.
19:48 That is, again, until the box is opened and the fate of the cat is observed.
19:52 The above is a famous thought experiment designed by the Austrian physicist Erwin Schrodinger
19:57 in 1935.
19:59 Legend has it, during a conversation with Albert Einstein, it illustrates a paradox
20:03 of quantum mechanics.
20:05 Theories on quantum superposition suggest that any given particle only becomes that
20:10 particle when it is observed; that before it collapses into itself, it can exist in
20:15 multiple states.
20:16 But what does that mean as to its true nature?
20:19 The paradox highlights many things.
20:21 One, a fundamental problem in quantum mechanics of how and when a quantum system collapses,
20:27 transitioning it from a superposition of states to a single, definite state.
20:32 Two, it challenges our classical understanding of reality itself, suggesting that objects
20:37 are wholly indefinite, and therefore much more complex and mysterious than we currently
20:42 understand.
20:43 And three, some interpretations of Schrodinger's cat suggest that consciousness plays a role
20:48 as well.
20:49 For example, if we weren't conscious to observe, then what, if anything, would happen
20:54 next?
20:55 This, in turn, raises questions about the nature of consciousness and its relationship
20:58 to the physical world.
21:00 And ultimately, whenever you find yourself doubting even your most inherent physical
21:05 experiences, even your most inbuilt thoughts and intuitions, then that can be a pretty
21:10 scary place to be.
21:11 But they laughed at Jules Verne, too.
21:15 The Soraites Paradox, also known as the Paradox of the Heap
21:19 The Soraites Paradox is a philosophical puzzle that deals with vagueness and the problems
21:24 it presents.
21:25 In its most popular form, it revolves around a heap of sand.
21:29 If you have your heap of sand and remove one grain at a time, then at what point does it
21:34 stop being considered a heap?
21:36 Conversely, if you add one grain to another, and then to another, and so on, then when
21:41 do your grains become a heap?
21:43 The word "soraites" derives from the Greek "for heap", but this is about more
21:47 than just sand.
21:49 It showcases how the imprecision of language can lead to logical absurdities.
21:53 Sticking with sand for now, the key issue is that there seems to be no clear answer…
21:58 because one grain of sand never makes much difference.
22:01 However, we know intuitively that there must be some point at which we'd no longer consider
22:06 our collection of grains to constitute a heap, or vice versa.
22:10 In another variation, it's known as the Bald Man Paradox, because at what point does
22:15 a man with a gradually decreasing number of hairs become bald?
22:19 Either way, it exposes problems in defining terms where there are borderline cases without
22:24 sharp boundaries.
22:26 Whenever there is vagueness present, which in truth is most of the time, because so much
22:30 of language - and so much of our communication methods - are ultimately up to interpretation.
22:36 For scientists, and indeed for anyone interested in precision, the Soraites Paradox is concerning
22:42 because many scientific concepts rely on clear definitions and thresholds - for example,
22:47 a boiling point.
22:48 But if such points are merely vague constructs when you really think about them, without
22:52 any truly inarguable before and after moment, then it becomes extremely challenging or even
22:57 impossible to establish facts.
23:00 From another point of view, the Soraites Paradox challenges the concept of gradual change.
23:05 In fields like biology or psychology, where categories like illness or mental health conditions
23:11 often exist along continua without clear dividing lines, the problem forces us into sometimes
23:17 difficult conversations about classification systems - about how to differentiate, and
23:22 therefore diagnose, between one medical complaint and another, for example.
23:26 Similarly, it's a paradox that might be applied to decisions over law and order, right
23:31 and wrong, justice and injustice.
23:33 It has an effect over social sciences such as demographics, over finance and money - where
23:39 pennies and cents eventually do make pounds and dollars - over education and the question
23:43 of precisely when someone is qualified enough to fulfil a certain role.
23:47 In all cases, the categorization criteria can seem arbitrary… and yet it will inevitably
23:52 carry significant implications.
23:54 Be that for research, medical treatment, policy-making, funding approval… the list is endless.
24:00 And that's why the Soraites Paradox is a source of constant concern… and even fear.
24:12 The Omnipotence Paradox If you ever find yourself questioning the
24:15 existence of God, then perhaps this is the paradox for you in particular.
24:19 The Omnipotence Paradox poses a fundamental challenge to the concept of an omnipotent
24:23 being or creator.
24:25 It asks the question, "Can an omnipotent being create a stone that they cannot lift?"
24:30 If they can create such a stone, then their omnipotence is limited by their inability
24:34 to lift it.
24:35 However, if they cannot create such a stone, then their omnipotence is limited by their
24:39 inability to create it.
24:41 For some, this is simply enough to prove that God doesn't exist.
24:45 It's a logical conundrum that just doesn't seem to fit with the beliefs and stories regarding
24:49 an all-seeing, all-powerful, supernatural force.
24:52 However, the majority of scientists aren't necessarily even thinking about the problem
24:56 from the point of view of some kind of supreme being.
24:59 Instead, this is a seemingly irrefutable puzzle that asks some pretty tricky questions about
25:03 the nature and limitations of power… with a potentially wide-reaching and even existential
25:09 impact.
25:10 Consider humankind's long-running bid to develop a "theory of everything" in physics.
25:15 In short, it boils down to an attempt to finally explain reality in full.
25:20 To leave nothing unknown, and to reach a rule that can and will explain every possible occurrence.
25:25 But even in our wildest dreams, is that ever really achievable?
25:29 The omnipotence paradox could suggest that no, it isn't.
25:32 It could imply that logic itself has limits, which is a potential death knell to scientific
25:38 inquiry in general.
25:39 It then poses questions about whether we can ever fully comprehend or explain our universe
25:44 using reason alone, since reasoning seems capable of leading us into contradiction.
25:49 At best, that's a headache for scientists.
25:52 At worst, it's the realisation that nothing ever actually matters.
25:56 The omnipotence paradox also throws a seemingly irretrievable fly into the ointment for any
26:01 future technology predictor or advanced civilization forecast.
26:05 With the Kardashev Scale - probably the most well-known measure of its type - there's
26:09 always, theoretically, another level above.
26:12 If one entity rules over this reality, then another rules over theirs, and another over
26:16 theirs, and so on, indefinitely.
26:19 But essentially, in everyday life, this is a paradox to prove that nothing is ever entirely
26:25 complete, completely correct, or fully under control.
26:28 There will always be a logical way to ruin it.
26:31 And this inescapable lack of control can feel deeply unsettling.
26:35 "This is not about my life, or Cooper's life.
26:39 This is about all mankind.
26:42 There is a moment."
26:45 Quantum Immortality
26:47 To put it mildly, we know that quantum mechanics is strange.
26:51 Dial down far enough into the fabric of reality, and most of the rules we rely upon to make
26:55 sense of the macro-world basically crumble and self-destruct.
26:58 But, and even with that as a backdrop, theories on quantum immortality are enough to really
27:04 shake you up.
27:05 Here we're at a meeting point between thought experiments like Schrodinger's Cat - which
27:09 serves to highlight how there are multiple states at the quantum level - and what's
27:12 known as the "Many Worlds Interpretation".
27:15 First put forward in 1957 by the US physicist Hugh Everett III, the Many Worlds Interpretation
27:21 is a particular understanding of the multiverse.
27:23 It says that every possible outcome of every quantum event does actually occur in a separate
27:29 universe.
27:30 It says that there are an infinite number of universes, and also implies that each one
27:34 of them houses a different version of you.
27:36 Typically, it's imagined by picturing that in one universe you wore a blue shirt today
27:41 instead of a red one.
27:42 In another, you ate an orange instead of an apple.
27:44 However, it goes much deeper.
27:46 In the more traditional understanding of life, the universe, and everything, we know that
27:50 we all die at one point in the future.
27:53 Death is an inevitable part of life.
27:55 But, through the prism of many worlds, perhaps it isn't.
27:59 Quantum immortality is a controversial and highly speculative hypothesis.
28:03 But in simple terms, it implies that, for every potentially fatal event, there's a
28:07 branch of reality where the person that's suffering that event survives.
28:11 In fact, there should be multiple branches of reality where they survive, and only one
28:15 where they die.
28:16 At first, this seems like it should be a good thing.
28:19 We know that various fields of science are busily trying to achieve immortality so that
28:23 we really can live forever - even in this particular timeline.
28:27 But quantum immortality also presents some major ethical dilemmas.
28:31 First, there's the somewhat unsettling loss of human narrative at play.
28:35 Our lives as we typically understand them are built around key moments which are essentially
28:40 bookended by the most key moments of all - birth and death.
28:43 But if true, quantum immortality removes the latter, and arguably changes what it means
28:48 to be human.
28:50 Even more worrying, however, scientists and philosophers have before mused that quantum
28:54 immortality could lead to a belief that none of our actions in the here and now have consequences
28:59 - a highly dangerous notion.
29:01 Equally, turn the potential paradox on its head, and we might just as well label quantum
29:06 immortality as "quantum prison" - as an overriding construct to reality that no one can ever
29:11 escape from.
29:12 Which, in turn, leads to deep-rooted questions about the nature of free will - about whether
29:17 it ever really exists at all.
29:25 Roko's Basilisk.
29:26 Perhaps no other paradox has generated quite as much modern controversy as this one has.
29:31 So much so that it's now something of a cornerstone for contemporary ideas on science and technology.
29:37 Roko's Basilisk is a thought experiment that emerged from the online community, LessWrong
29:42 - a forum for discussing future tech topics, and especially artificial intelligence.
29:48 Roko refers to the original poster on the forum, while the Basilisk is a nod to a legendary
29:52 beast, king of the serpents in mythology, that's said to kill anyone who looks into
29:57 its eyes.
29:58 In essence, Roko's Basilisk is a hypothetical scenario involving an all-powerful AI that
30:04 comes into existence in the future.
30:06 This AI is supremely dedicated to achieving its goals and ensuring its own creation, as
30:12 it's predicted in general that many AIs will be.
30:15 But now is when things get scary.
30:17 The paradox suggests that this particular AI would punish those who knew about its possible
30:22 existence but did nothing to help it achieve its goal.
30:26 In other words, just by knowing about this potential AI god-like entity, the Basilisk,
30:31 you might be at risk of future retribution unless you make it a reality.
30:35 And naturally, as soon as talk of Roko's Basilisk comes up, then those involved are
30:40 aware of it, and theoretically are at risk unless they act.
30:44 The circular nature of Roko's Basilisk reportedly inspired panic in some who read the original
30:49 post, and discussion of it was even banned on LessWrong for a number of years.
30:54 As such, it's been variously described as a "dangerous" thought experiment, as
30:58 it implies that even our own thoughts aren't safe in the face of the rise of AI.
31:03 That we'll one day be so totally at the mercy of machines, that we'll be inescapably
31:08 punished, even tortured, for past actions or inactions that we could and can do very
31:14 little about.
31:15 It might also be labelled as an "information hazard", as it is theoretically information
31:19 that's hazardous to know.
31:21 More broadly, the Basilisk has been compared to Pascal's Wager, attributed to the 17th
31:26 century French philosopher Blaise Pascal.
31:29 It's a proposed gamble on belief in God, arguing that if God exists and you believe,
31:34 you gain everything, such as eternal life, but if you don't believe and God exists,
31:38 you lose everything, via eternal damnation.
31:41 So, logic says it's best to live as though you do believe, just in case.
31:45 Unsurprisingly, Roko's Basilisk is by no means the only AI-centric paradox out there,
31:51 either.
31:52 Another especially troubling example is the "paperclip maximizer", proposed in 2003
31:56 by Swedish philosopher Nick Bostrom.
31:58 It suggests that an AI designed to make paperclips could ultimately decide to make paperclips
32:03 until the universe is nothing but paperclips.
32:06 Or it could deem it best to make paperclips of the atoms inside us, the otherwise useless
32:11 humans, as per its one-track perspective.
32:21 The Dark Forest With the Dark Forest hypothesis, we at once
32:24 have a potential solution to another paradox, the Fermi Paradox, and the outline for a separate
32:30 paradox relating to cause, effect, action, and intent.
32:34 The Dark Forest is primarily a thought experiment that explores the potential dangers of revealing
32:39 oneself to other civilizations in the vastness of space.
32:43 It was proposed by the Chinese science fiction writer Liu Shixin in his novel, The Dark Forest,
32:48 the second installment in a trilogy starting with the Three-Body Problem.
32:52 The theory is based on the premise that the universe is a dark forest, where every civilization
32:57 is a hunter with a weapon, lurking in the shadows, trying to avoid detection.
33:02 Or at least, that's what every successful civilization is doing.
33:06 The reason for this is simple; if a group reveals its existence by emitting signals
33:10 or engaging in any other activities that can be detected by others, then it is immediately
33:15 putting itself at risk of being attacked and destroyed.
33:18 As there's no room for trust or cooperation in the dark forest, any civilization that
33:23 is discovered by another is assumed by them to be hostile, and must therefore be eliminated.
33:29 This leads to a chilling conclusion; the only way for a group to survive is for them to
33:33 remain hidden and silent.
33:35 And as a result, the dark forest is now a leading potential solution to the Fermi Paradox,
33:41 which asks, "Where are all the aliens?"
33:43 Clearly, there are a number of reasons why many are scared by this.
33:47 It suggests that the universe is simply a much more dangerous place than we may have
33:52 ever imagined; that it's a cold and unforgiving wilderness where only the most paranoid and
33:57 ruthless can survive.
33:59 But also, because we know that via radio communication and even probes such as the Voyagers, humankind
34:05 has before actively sought to make its presence known.
34:09 Then it implies that we've already sealed our own doom; that there's no rowing back
34:14 from the actions we've already taken.
34:16 Finally, though, some interpret the dark forest as being indicative of the pitfalls to human
34:21 nature itself.
34:23 In any situation, not just with regard to hypothesized alien contact, we project our
34:28 own behaviour onto others, and assume that they'll act as we do.
34:31 To some degree, it might be viewed as a positive mindset.
34:35 But ultimately, for so long as there's even the possibility for a negative, destructive,
34:40 or even fatal outcome, then that's what will happen, time and time and time again.
34:45 In short, while no one asked to be in the dark forest, no one can escape it either.
35:07 So how's your brain?
35:08 Muddled?
35:09 Befuddled?
35:10 Or possibly enlightened?
35:12 Air your thoughts in the comments.
35:14 Be sure to tell us which paradox you found most interesting… or most terrifying.
35:19 And if you know of a paradox we haven't covered, or if there's any you'd like to
35:22 know more about, then let us know.
35:28 What do you think?
35:29 Is there anything we missed?
35:30 Let us know in the comments, check out these other clips from Unveiled, and make sure you
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