The Old Question Nobody Has Been Able to Answer

this video is kindly sponsored by keeps find out more later in the video hey 42 here in the southeast of england on the banks of the river way sits a quaint leafy town known as waybridge it's prim streets are lined with artisan coffee shops and bohemian boutiques and aside from once hosting the marriage of henry viii to catherine howard it's enjoyed a fairly uneventful past but earlier this year the town's residents were scandalized by a mystery tree fella who under cover of darkness took a chainsaw to nearly 50 trees instead of taking the wood home with him this timber tyrant left his woody corpses strewn across the town's paths roads and river leaving the locals with an unsightly mess and a number of unsettling questions why if the culprit didn't need the wood did he embark on such a destructive spree how did he manage to cut down so many trees without making a sound and if a tree falls but nobody is there to hear it does it still make a sound whilst you're sitting there pondering 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orbiting the sun of course there is but in 1710 berkeley decided to out philosophize everyone by claiming that the entire physical world just plainly doesn't exist you see berkeley was an idealist not in the way that word is often thrown around today to mean someone who's a little bit naive like your grandma who just doesn't understand why that mr putin man on the news can't just make friends with everyone no barkley subscribed to a philosophical doctrine called idealism idealists believe that the essential nature of reality doesn't lie in the material world around us but in things like consciousness ideas and reason it's a tricky concept to get your head around and you wouldn't be alone in raising an eyebrow or two when the writer samuel johnson discovered barclay's view he was so outraged that he kicked a large stone and declared i refute it thus and that's because many of us subscribe to the pretty intuitive belief that there is a physical world one that exists completely independently from us we know this because our senses feed us information about it every second and because well if we don't exist in a physical world where the hell are we but barkley believed that the things our senses tell us about reality and reality itself are actually the same thing take a familiar object like a strawberry it has knowable properties it's red small a little bumpy and sweet but now try to imagine that strawberry without the redness and without its shape or its texture or its taste it's pretty much impossible because what is a strawberry without its properties so if objects are inseparable from their properties and those properties can only be perceived as sensory experiences in our minds then there can't be a physical world that exists separately to us right this was barclays doctrine essa est passippi or to be is to be perceived if we aren't there to perceive an object it simply doesn't exist now briefly returning to johnson's foot kicking the stone barkley would have expected him to feel pain but he would also have argued that the stone didn't exist outside of the sensory experiences it created i.e pain and so if a tree falls in a forest but nobody is there to hear it then according to barclay no it doesn't make a sound because there is no tree that all sounds completely mental i know but berkeley wasn't the first philosopher to question our relationship with reality around 70 years earlier rene descartes released his magnum opus mediations on first philosophy in the second mediation he considers how everything he knows about a piece of wax its smell colour and texture changes once the fire melts it the wax itself remains but the sensory experiences don't then he rambles on about wax and his limbs for another five pages before eventually reasserting a famous maxim he'd originally penned four years earlier i think therefore i am around this time science was having a lot of fun overturning most of what we knew about the world in the 1660s robert hook discovered the cell showing that all living organisms are composed of tiny structural units that are imperceptible to the human eye meanwhile isaac newton took an interest in colours [Music] which in hindsight wasn't his smartest move because in a dramatic demonstration of dedication to knowledge he prodded the underneath of his eyeball by shoving a blunt sewing needle called a bodkin inside his eye socket just to see what would happen but every masochistic act has a silver lining because in doing so he proved that white light is composed of a spectrum of seven visible colors and if light itself is the source of color then it couldn't be a property that belonged to external objects objects have no colour instead they reflect light which our brains then interpret as colour so with scientists everywhere suddenly bulldozing every long-established axiom it's hardly surprising that philosophers began to question the reality of the world if an experience as fundamental as color is purely a manifestation originating within our minds how much influence do we actually have on reality of course this kind of skepticism wouldn't be very useful in everyday life imagine for example explaining to your neighbor that you didn't feed her cat because there is no cat so let's just presume for the time being that i really exist you really exist and there are definitely things out there called trees that exist independently of us if one of them fell but you or i weren't there to hear it would it make a sound well put simply the answer is it depends how you define sound according to psychoacoustics the study of how humans perceive sound when a tree falls it compresses the air particles around it causing them to vibrate the faster it falls the more they vibrate those air particles then vibrate the particles around them creating air waves these waves travel through the air at 343 meters per second transferring energy to surrounding objects if your ear was one of those objects a spiral structure within known as the cochlea would vibrate which converts the physical energy of the wave into electrical impulses which surge to the brain for an auditory nerve finally your brain does its human calculator thing to interpret those signals as sound in your mind the bigger the vibrations the louder the perceived sound so in a nutshell if a tree falls but there is nobody there to hear it then no according to science it wouldn't make a sound because sound is not a physical property of our world it is simply the interpretation of information by the brain obviously there would still be vibrations if you weren't around during the tree's demise and those physical vibrations will have a small effect on the surrounding environment but sound needs to be perceived to exist and therefore requires a hearer to be present and i can sort of prove to you that sound is not a physical property of our world but something that only happens inside your head because your brain can be fooled pretty easily take horror films for example it would be inconvenient and probably illegal to convince an actor to actually chew human flesh but you can create a pretty convincing zombie bite by chomping down on a tomato you can crush a pepper to replicate a skull crush and you can create the sound of intestines being pulled out by molesting a raw chicken which oddly enough is not illegal but we can take this neural trickery one step further still if part of an audio recording is replaced by a period of silence [Music] the gaps would be quite obvious but if someone starts coughing over someone else speaking your brain simply works out what should be there in place of the cuffs and fills in the gaps and here's an even cooler example listen to this digital piano and see if you notice anything odd at first it just sounds like a cat trapped inside a piano having a seizure but observe what happens once words are put on the screen [Music] creepy right this is because our brains utilize context and prior knowledge to make sense of the world around us you understand english only because of the prior knowledge your brain possesses and the context that that person you're talking to is speaking english icelandic is just a bunch of complex vibrations yet an icelandic native can decipher those vibrations because of his prior knowledge and context whereas you just hear the vague grumblings of an angry viking so for yet another time in this video to answer the old chestnut if a tree falls in a forest and no one is around to hear it does it make a sound no it creates a disturbance of the air but it does not make a sound [Music] course we also have to assume no animals are present since they have the same vibration to sound conversion engine otherwise called ears and the brain as we do but hold on a minute a tree has plenty of other biological friends around it what about plants evidence that plants can and do respond to sound has mounted over recent years we know that sound stimuli can make plants more tolerant towards infections more resistant towards droughts and even grow more quickly in one experiment where plants were placed next to an opaque tube with water constantly rushing through it over time the plants grew towards the tube suggesting they could hear the water passing through the pipe this might come as a surprise especially because plants lack one of the essential components of hearing an ear although we don't yet fully understand how they pull it off it's thoughts the bowl shape of many flowers may have evolved as a way to catch more of the vibrations around them and in a sense turn up the volume on their environment the evening primrose for example produces a sweeter nectar roughly three minutes after hearing the sound of a bee buzzing or a synthetic sound reproduced at a similar frequency but it won't respond to any other frequencies so maybe we should talk to plants to help them grow after all but be careful how you talk to them they don't respond well to shouting so keep things sweet with a low dusted toe ideally around 115 to 250 hertz so it turns out if a tree falls in a forest but no human or animal is present to hear it it will probably still make a sound from the perspective of nearby plants so far we've attempted to answer this question using a combination of philosophy and science and surprisingly they both agree that perception plays a big role in whether or not something makes a sound where idealism and science differ however is that according to idealism a lack of perception equates to a lack of existence and hence a lack of a tree science on the other hand typically assumes something definitely does exist even if our senses aren't experiencing it directly take neptune for example scientists predicted the existence of neptune before they saw it because there were discrepancies between calculations and data for the planet uranus using the laws of physics einstein was able to successfully predict the bending of light and the existence of black holes in the 1950s scientists were able to anticipate rising co2 levels and we now work on the assumption that dark energy exists a type of energy that acts in opposition to gravity yet we still haven't observed it and perhaps we never will but as science evolves so may the answer to the classic falling tree conundrum einstein believed the world continues to function exactly the same regardless if we are around to observe it as he so eloquently puts god does not play dice with the universe some quantum physicists however beg to differ they argued that each of us lives within our own virtual reality of sorts and the universe behaves in a unique way depending on who is observing it and from where this mind-melting concept was conceived by niels bohr and werner heisenberg back in the 1920s and is known as the copenhagen interpretation it's an idea so convoluted even its creators bow and heisenberg couldn't agree with each other about what it actually was whether you subscribe to quantum mechanics established science idealism or pastafarianism i think the real lesson here is that it's our experiences of life and the world around us not the objects themselves that give us real meaning perhaps in a peculiar and somewhat reckless way this was what the timber tyrant of weybridge was trying to tell us all by chopping down 50 trees but let's be honest he was probably just stupid and blind drunk thanks for watching check out my new podcast random interesting facts available on youtube spotify apple podcast and anywhere else you get your podcasts link in the description below thanks

Channel: Thoughty2

Views: 1,212,139

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Id: dJztOOQ0_lM

Length: 19min 39sec (1179 seconds)

Published: Wed Jun 16 2021