If a tree falls in a forest, does it make a sound?


If a tree falls in an empty forest, does it make a sound? Originally this question was made for meditative purposes, but answering the question incorporates several fascinating ideas about human perception and psychology. Tune in to learn more.

Robert Lamb: Hey. Welcome to Stuff to Blow Your Mind. I'm Robert Lamb.

Julie Douglas: And I'm Julie Douglas.

Robert Lamb: Tell me Julie, what does your cat do all day when you're not [inaudible]?

Julie Douglas: Well, I think I've told you before that he is working ala inception to plant thoughts into my mind.

Robert Lamb: Okay.

Julie Douglas: Yeah, so he's just working on mathematical models basically.

Robert Lamb: Okay. That's your theory, right?

Julie Douglas: No, that's what my webcam is telling me.

Robert Lamb: Oh, that's what your webcam is telling you?

Julie Douglas: Yeah. We've got a little blackboard in the office and -

Robert Lamb: Oh, okay. See, I knew I should - see, we don't have a webcam set up, so it's all a mystery to me what the cat may or may not be doing in the house or outside the house while I'm away. She could be sleeping on the pillows all day where she's not allowed. She could be turning on the Xbox. I have no idea.

Julie Douglas: Huh. This is sort of like that proverb.

Robert Lamb: Yeah.

Julie Douglas: If a tree falls in the forest, and no one is around to hear it, does it make a sound?

Robert Lamb: Yeah, it's a - this is an old philosophical question. The idea is not necessarily to answer the question. Of course, some people listening to this probably have that kind of mind where they're like, "This is something we can test. We can do this," but it's more about training the mind and throwing a good paradox at it to beef it up.

Julie Douglas: Okay, so it's like a thought sandwich that we can chew on.

Robert Lamb: Yeah, a big, chewy thought sandwich.

Julie Douglas: It's a double-decker of a sandwich.

Robert Lamb: Yeah, you could soften it up if you put it in the microwave a little bit, but straight up, it's gonna be pretty tough.

Julie Douglas: Should we talk about just the bones of it, the fact that the sound is vibration that's carried through a medium at a frequency range capable of being heard by the human ear? So there's that. There' s the sound that's out there, so regardless of whether or not you're here to listen to it or I'm here to listen to it, sound is going to exist, right?

Robert Lamb: Yes, but if that sound isn't received though, that kinda gets into the question. If the sound is not received by a listener, by an observer, then did it take place? Was it really sound?

Julie Douglas: See and I think there are multiple, multiple answers to this, right?

Robert Lamb: Right.

Julie Douglas: Because you could say, "Well, if it - other organisms are listening" first of all, but I guess this is just concerning us Homo sapiens.

Robert Lamb: Yeah. And it really comes down to what it says about our perception and how it affects our understanding of the universe.

Julie Douglas: Okay. So I'm thinking right now like patterns that we tend to pick up on.

Robert Lamb: Right.

Julie Douglas: Right, so sometimes I'll notice something that's happening in the world, and I'll sort of think, "Oh my goodness. Armageddon is just around the corner."

Robert Lamb: Yeah, there's always something like - especially if teenagers do something like suddenly everybody's paying attention to what these teenagers are doing and it's, "Oh my goodness. The end of the world is near."

Julie Douglas: Right.

Robert Lamb: They're all listening to this horrible music or they're wearing these jean shorts that are going to bring about the end times. And people have been saying this for ages.

Julie Douglas: I didn't know that jean shorts was the cue for the four horsemen of the Apocalypse.

Robert Lamb: Well, no. It's the Antichrist. The Antichrist will come in the form of -

Julie Douglas: Oh, of jean shorts?

Robert Lamb: Yeah, in jean shorts. I've been rereading the Name of the Rose recently, so I have a lot of this apocalyptic stuff in my mind. So I can imagine an old monk talking about - explaining very detailed why teenagers in jean shorts are the sign that the Antichrist is walking among us. So - but anyway, at any rate, we've been reading too much into data for a long time and we continue to do it even though it might relate more to say geothermal events than it does to the arrival of the Antichrist on Earth.

Julie Douglas: Okay. So if I'm looking at the weather for instance and I notice that there have been a ton of floods or hurricanes or tornadoes, and I start to think to myself, "Oh my goodness. What's going on? There seems to be more activity and weather than ever before. Could it be true?"

Robert Lamb: Right. And you can totally freak out like that on an individual level, but you also see it broadly in scientific studies where it's called a reporting effect. Now a great example of this is something that I came across when I was writing an article titled "Are Volcanic Eruptions Increasing" for Discovery News. And it's - I have done a number of these that I'll tackle - seemingly simplistic questions. And I was really delighted with how interesting this one was. The short answer is no. And I didn't just look this up. I talked to some experts.

I talked to Lee Siebert, the director of the Smithsonian Global Volcanism Program or the GVP as the kids call it in their jean shorts. And he broke it down for me; great guy. He said that basically, we've been - they've been looking - the GVP has been looking at volcanic eruptions for 40 years. And if you really start digging, you have about 200 years worth of data to look at. So if you plot those last 200 years, there's a clear increase in the number of eruptions over time. Look at the data and you're like, "Oh well, they're" - and this is totally - the numbers are totally off. You read them and you're like, "Oh, there's five this year and the next year there's ten. Then, there's 15. Volcanic activity is clearly going up." But that's - but it's not the case. This is the reporting effect in action because -

Julie Douglas: Tell us just straight: what does that mean? Why would we see that pattern and why wouldn't it be true?

Robert Lamb: Well, you take this apparent increase in volcanic eruptions and you can compare it to other data and things start making a whole lot more sense. For instance, the apparent increase in volcanic eruptions parallels the rise in global population. It parallels human encroachment into areas of volcanic activity. There are suddenly more people around to observe volcanoes erupting. There are more people living in the vicinity of volcanoes to report on it. You see the number increase with the evolution of our telecommunication systems. Suddenly, not only can more people - more people are in a position to observe volcanic activity, but they're in a better position to report it.

Julie Douglas: So the - yeah, tweeting is what's going on.

Robert Lamb: Right, tweeting about it, e-mailing, call - just as simple as being able to call somebody or - instead of just writing a letter or just marking it in your journal.

Julie Douglas: So that means that all of a sudden, we have an avalanche of data.

Robert Lamb: Right. And then another interesting aspect that they encountered is that if you - you look at the apparent volcanic activity, just based on reports; you see two really curious dips in volcanic activity in the 20th century, once during the first world war and then again during the second world war. Now you could make the argument that these world wars caused volcanic activity around the world to decrease, but of course you would be - that would be insane.

Julie Douglas: Right, I'm raising my eyebrows right now at you.

Robert Lamb: That's kind of like - it comes down to the fact that we were pretty distracted during those times. We had world wars going on and we just didn't have time to really focus on what the volcanoes were doing for the most part. Again, it's kinda like the cat: if you've ever been really busy and you don't notice the cat doing anything, it doesn't mean the cat's not doing anything. In fact, it may result in the cat doing all sorts of horrible things to get your attention depending on the cat. It's just where your attention is at.

Likewise, they found that the following - the really dramatic eruptions of Krakatoa in 1883 and Mount Pelèe in 1902, you saw an apparent increase in volcanic activity following those events. Now it would be a lot easier in this case to say, "Oh, well, there's just a huge volcanic vent, so these other volcanoes were acting up too." No, it's just that you have this huge event and people were suddenly paying a lot more attention to what all the other volcanoes are up to. It's kinda like somebody hits the news for something: somebody robs a bank while wearing tight jean shorts.

And then suddenly, everybody's focused on jean shorts: "Are more people wearing jean shorts? Are more crimes being committed with jean shorts?" No, it's just suddenly our mind is focused on it.

Julie Douglas: It was that one monk, right?

Robert Lamb: Yeah.

Julie Douglas: Should we go back and look at this seriously? Yeah.

Robert Lamb: Clearly.

Julie Douglas: Yeah, all right, okay, so I'm seeing. So the pattern isn't necessarily telling the whole truth. When you really peel back the layers, you see that we just have more access to more data. So even with hurricanes, right; this is the same thing?

Robert Lamb: Right, hurricanes. You see reporting effects in - with hurricanes, other kinds of atmospheric anomalies. You see it in economic studies. You see it in health reports. And it just underlines that no matter what we're looking at and trying to understand, we can look at it to the point where we don't really have a good understanding of it. We've analyzed it too much. We've over analyzed it and we were not - we have to take that information that we've gathered and put it in perspective with pretty much everything else in the universe to make complete sense of it.

Julie Douglas: Yeah, I'm even thinking about slate. Don't they have a feature that's sort of the bogus trend of the week?

Robert Lamb: Oh yeah, I think they do.

Julie Douglas: That they sort of debunk the myth? I think they had one; it was like rompers, like everybody's wearing rompers.

Robert Lamb: Now refresh my memory: what is a romper?

Julie Douglas: Romper is - oh, how to explain this? It's a sort of onesie for grownups and -

Robert Lamb: Like a prison outfit or like big feetie pajamas?

Julie Douglas: No, no I should say there - it's like shorts; a shorts onesie. And so there were a lot of magazines that were saying, "It's come back and it's the sexiest thing ever. Men love it."

Robert Lamb: Like cutoff overalls?

Julie Douglas: Cutoff overalls: yeah, but with sleeves sometimes. Yeah, see; you're getting the idea.

Robert Lamb: Yeah, it's kinda - it sounds like a sneed.

Julie Douglas: Oh right. Is this the blanket the -

Robert Lamb: No, that's the Snuggie.

Julie Douglas: Yeah, the Snuggie.

Robert Lamb: But then the Sneed was the thing that everyone needs that the oncler in The Lorax made.

Julie Douglas: Oh, okay.

Robert Lamb: It was some sort of horrible garment that appeared to have no function, but became really popular because the oncler was telling everybody they needed it, if I remember correctly.

Julie Douglas: Yes, that's right. So there you go. You're - there's pattern recognition everywhere, even when patterns don't exist, I think is what we're saying. So whether or not it's an increase in volcanic activity or the onslaught of the romper onto American women's bodies -

Robert Lamb: Or more trees falling all over the world because we're paying attention to them.

Julie Douglas: Yes, that's right; going back to The Lorax actually.

Robert Lamb: Yeah. Oh yeah, so a lot of trees fall in that. It all comes together.

Julie Douglas: That's right. So I'm thinking about quantum indeterminacy and how this relates back to that because we always have to take on a little quantum in each podcast.

Robert Lamb: Okay, quantum indeterminacy and this is the apparent necessary incompleteness in the description of a physical system that has become one of the characteristics as standard description of quantum physics. That's your stuffy description.

Julie Douglas: Right, in that the - right, the stuffy - and the important part of that is the apparent necessary incompleteness. So before this, prior to quantum physics, it was thought that a physical system had a determinant state which uniquely determined all the values of its measurable properties, and conversely B, the values of its measurable properties uniquely determine the state, but you throw quantum into the mix.

And essentially, quantum indeterminacy is saying, "Actually, there's all sorts of outcomes, and in fact, we could be wrong. We could - this is a sort of place holder and what we're trying to determine and it is - we'll just go ahead and say right off the bat that it is incomplete. It is not the end all the be all. We don't know if a tree is falling in the forest with quantum indeterminacy, but we know the possibility is there.

Robert Lamb: Right.

Julie Douglas: Right, so it's a game of possibilities.

Robert Lamb: Well, of course it instantly brings to mind, especially since we mentioned cats earlier, the idea of Schrödinger's cat.

Julie Douglas: Yeah.

Robert Lamb: Yeah, which of course the idea is that the cat's in a box and you have this sort of elaborate system set up with the decaying radioactive substance and -

Julie Douglas: Yeah, atomic particle, right?

Robert Lamb: Yeah. And it has like an hour and it -

Julie Douglas: It has a 50 percent chance of decaying, right? And a 50 percent chance of not decaying.

Robert Lamb: Yeah, there's a Geiger counter and if it decays, then a hammer hits a flask and poison - it fires a gun. There are various -

Julie Douglas: Various ways to kill the cat, I think.

Robert Lamb: Yeah, but it basically comes down to the fact that there's a box, kind of like your home and there's a cat in it and you cannot be sure exactly what state the cat is in. And since you can't be sure, in the case of Schrödinger, the cat is alive or dead. The cat is there in what is called a super position meaning that it is both alive and dead. You don't know for sure. It's just a complete uncertainty. Likewise right now: what's my cat, Biscuit doing? Is she laying on a pillow? Is she playing the Xbox? I don't know. I just don't know.

Julie Douglas: Mine has just broken through with the theory of everything.

Robert Lamb: Oh, well, that's because you've got a webcam.

Julie Douglas: I know. I know. I just saw it. I saw - wow.

Robert Lamb: But see, the box is open for you because of the webcam. For me, the box is closed, so anything is possible.

Julie Douglas: Right. So what I think is cool about this concept is that it really is a driving force in science. When we think about science, we think about what we know and we think about this sort of infallible, A is A and B is B and C is C, and that's the story, folks; when in fact, science is just a murky, murky field with all sorts of spooky things happening. And there's a neuroscientist named David Eagleman who gave a talk at the School of Life about this uncertainty, this quality in our universe that we've come to understand is the limits of our knowledge essentially.

Robert Lamb: Right, he has kind of a rock star persona as I remember. He's pretty - a pretty hip dude.

Julie Douglas: Oh yeah. He starts out his conversation by saying, "Hey, do you guys know about deep field observation?" He'll ask the audience and this [inaudible] case of course like half of them know. He says, "All right, cool. Let me just blow your mind right off the bat." And then he says, "Okay, there's the Hubble telescope; went up in 2003 and has been orbiting in a geosynchronous orbit. And they just decided to point their lens at a really tiny spot in space. And what did they find after millions of seconds of data? They thought maybe they'd find a start or something. They ended up finding 10,000 galaxies, which is thousands of billions of suns observed in a tiny, tiny patch." And to me, that was the ultimate example of the vastness of what we don't know.

Robert Lamb: Right, especially in this he mentions that people were like, "Why don't we just analyze everything to that extent?" And we could, but it would take millions and millions of years to do, so -

Julie Douglas: Yeah, right. If you pointed that lens, if you tried to map out the entire space, there's no way we could do it, but we can - that tiny little spot, we can gather data on.

Robert Lamb: Right; yeah, just a tremendous amount of focus on one portion of the sky.

Julie Douglas: Yeah. And so he uses this as a jumping off point to say, "Everything that we thought was true, we kinda have to back up and look at." And then he goes into this concept of possibilionism, which he used actually as a joke term a while back and it's actually gained some legs. Yeah, he was -

Robert Lamb: It sounds like something Jack Donaghy would make up on 30 Rock.

Julie Douglas: That's right, possibilionism. Lemon, it's the new -

Robert Lamb: Reagan.

Julie Douglas: Right, the new reaganism, but basically what he's saying is it's that the active exploration of new ideas, which is trying to understand the structure of that possibility space. So he's saying, basically, everybody is welcome at the table, but we're gonna use science to try to cut away at the parts that don't make sense to us and we're gonna acknowledge the real limits of knowledge that we have. And then he kinda talks about all the different puzzle parts that we have that we know about right now, but what we don't know about. And quantum theory is basically one of those things that he talks about.

He says, "It's given us a tremendous amount of information, but at the same time, we still are kind stuck even in that mode of what's right: the Copenhagen interpretation, or the many worlds theory?" So time collapse theory, which of them is right? Are there many, many worlds that we can observe or is there just this one world that we can observe because nothing beyond that exists? Which goes back to that tree in the forest, you know?

Robert Lamb: Right. Now you mentioned - when we were prepping for this, we went over relativity a little bit and about how the original theory of relativity is the idea of - it's - you can sort of compare that to a tree falling in the forest.

Julie Douglas: Right, with Einstein and basically saying, "Okay, this is my projection based on mathematics," but this is still just a thought. This is still a thought experiment in a sense?

Robert Lamb: Yeah, and it was something that subsequently, we had to prove, the things like observable time dilation, and also like gravitational lensing with stars of observing how this interesting relationship between time and space and its reality as space time/

Male Speaker: This presentation is brought to you by Intel, sponsors of tomorrow.

Julie Douglas: So yeah, basically when Einstein was looking at that, this was just the seeds for what we now can apply to different disciplines, to breakthroughs that we've had in science, but still, we have this unknown quantity and I think about dark matter as an example. We definitely underestimated the gravitational pull and now we find out that 90 percent or we think, of the matter of the universe that we don't know what it is or where it's coming from.

Robert Lamb: Yeah. It's kinda like - there was a - one particular Sherlock Holms story and I forget the title of it, but they're investigating a house and Sherlock was able to determine that there's not enough - based on the visible space, there's a secret room here somewhere. And dark matter's kind of a similar situation based on how much matter there should be in the universe, there's something missing, so therefore, dark matter.

Julie Douglas: Right. And that's a great example or a great analogy because we can't see it, but we know that based on our models that there has to be like 90 percent of something -

Robert Lamb: Something there; there's a hidden room and it's filled with dark matter and we just have to figure out exactly what that means.

Julie Douglas: Yeah. And then if you take it down to even just the level of what's available to us know like for instance, we've got photography which - high speed photography now, which we can slow down mundane events, even a dog lapping up water.

Robert Lamb: Oh yes, or a cat. There was recently a study on that.

Julie Douglas: Yeah.

Robert Lamb: Exactly how a cat's drinking.

Julie Douglas: Yeah, it's completely different than we ever thought, especially with the dog, if you look at it. We used to think the dog was using his tongue as a sort of cup and bringing all that water up into him, but now we understand that it's actually curling it's tongue under and getting the water in that way. So you begin to think to yourself how many things am I actually missing on a day-to-day basis because I'm not quite equipped to perceive things?

Robert Lamb: Yeah, like we slow it down even more and we see that when the tongue curls like a tiny dog head comes out of a hole in the tongue and then drinks the water.

Julie Douglas: That's not true.

Robert Lamb: It might be true. We just don't know yet. We don't know yet. We just can't be certain.

Julie Douglas: I really wish that were true. But it does make me think about another example which David Eagleman gives is that we've got photo receptors at the back of our eyes picking up signals and picking up a tiny slice of electromagnetic radiation spectrum, which is what we call visible light. The same stuff is passing through us via cell phones, but the difference is that cell phone signals: we can't decode them because we don't have the specialized receptors for it. So again, it brings us back to that question of maybe we're just ill equipped to be able to do more at this point in time in our evolution.

Robert Lamb: Right, we kind of end up thinking of the visible world, the world that's visible to humans as being reality; that it actually may work out to wear the version of reality - it would just seem like a slim slice of reality. The rest is like we've got blinders like a horse.

Julie Douglas: Yeah, yeah. And David Eagleman had this really great point. He was sort of talking about all the - where we are historically in terms of breakthroughs and saying, "Can you imagine being able to even understand a computer, let alone quantum computing if you didn't even have electricity to plug in that computer?"

Robert Lamb: Yeah, I can't even imagine understanding one with electricity, but that's me.

Julie Douglas: Right. It still breaks my brain, but so you think about where we're going to be on that timeline 100 years from now or 1,000 years from now. We essentially might look like cavemen and then all the things we think right now may just be some sort of guessing game that probability: half of it turns out to be correct; the other half: not correct. And this is, I think, one of the most important points that David Eagleman makes, which is that science really is a guessing game. It doesn't look - science does not move in a linear fashion. It takes great creative leaps, and then it tries to backfill to substantiate those leaps.

Robert Lamb: Yeah.

Julie Douglas: So that's another reason why science - scientists are rock stars.

Robert Lamb: Well, it goes back to taking into cosmology the idea of geocentricism and heliocentricism, the idea that okay, you're the center of the universe. Let's throw some math at that. Okay, that doesn't work out. The sun's the center of the universe. Well, that doesn't work out either. It's like they take this leap and sometimes the leap is based on things that aren't science, but then by - through scientific evaluation, they are able to determine whether that was a leap that's gonna land us onto solid ground or not.

Julie Douglas: All right, yeah. So I'm liking this because - this concept of scientists have stayed pipe smoking, plaid vest wearing men and women because - with mustaches; I'll just go that far is completely wrong. They're sort of like the graffiti artists trying to put things together. Graffiti artist sounded kinda cool, but as you said, they're just throwing things - they're throwing darts at the dartboard of ideas and just trying to get there.

Robert Lamb: Yeah. And one day they'll look back and say, "I can't believe that they thought that dark matter was a thing and they didn't know that dog tongues had a little bitty dog head that came out of them.

Julie Douglas: Right, exactly.

Robert Lamb: Totally didn't understand even their own pets.

Julie Douglas: And jean shorts; what was that all about?

Robert Lamb: Indeed.

Julie Douglas: But examples, I think of this, of this creative leap is with relativity as you had brought up before with Einstein. That was just a little seed of an idea before, but then it actually had some real time applications.

Robert Lamb: Yeah, and we were later able to observe gravitational lensing to see how light traveling near a very large start actually warps around it. Being able to ob serve how the clocks in an orbiting satellite - how time passes a little bit differently in orbit than it does on Earth.

Julie Douglas: Right, and that's the geosynchronous satellites, right?

Robert Lamb: Right.

Julie Douglas: And so that's what - that's how we keep time aboard spacecrafts.

Robert Lamb: Yeah, by being aware of the change.

Julie Douglas: Okay. And then we've got atomic energy and atomic warfare. These are huge things that were just predicated on a thought. Of course, a lot of math too, but turned out to be on the 50 percent right part of the board there.

Robert Lamb: Yeah, it's kind of like we're pawing our way blindly through a fog and the fog is the universe. We can never really see the whole picture, but we can sort of reach ahead and sort of feel our way through it and figure out what's going to be solid ground and what's going to be a plummet into an abyss.

Julie Douglas: We can't see the trees for the forest.

Robert Lamb: Oh, there you go.

Julie Douglas: All right. Well, that helps explain a little bit, but I think the coolest thing is that it helps us to understand that uncertainty is okay, right?

Robert Lamb: Yeah, uncertainty is a huge part of it.

Julie Douglas: Right, it's the building block of our knowledge.

Robert Lamb: Right. Yeah, the second you have everything figured out, that's where the problem is.

Julie Douglas: You're in big trouble. In fact, Voltaire said, "Doubt is an uncomfortable position, but certainty is an absurd position."

Robert Lamb: I always come back to the book of Job where Job's having a miserable time. I've probably mentioned this before, but then God is basically - and he decides to mouth of to God. God's like, "Who are you to ask questions; you're never gonna understand anything?" And it's a very - it's probably my favorite chapter in the bible because it's got - or book of the bible because it comes down to uncertainty, cosmic uncertainty, geologic uncertainty, philosophical.

Julie Douglas: Yeah. I like that chapter too and the one on jean shorts.

Robert Lamb: Yeah, the one on jean shorts is pretty good, but it's a cautionary tale.

Julie Douglas: Of course. You won't see any on me.

Robert Lamb: So if you wanna learn more about these topics, just visit the homepage and you can drop in quantum physics, relativity, jean shorts, whatever into the search bar and we have a plethora of articles for you to look over.

Julie Douglas: And don't forget to check out David Eagleman's talk on uncertainty which is on schooloflife.com.

Robert Lamb: And in the meantime, you can check us out on Twitter and Facebook. You can find us; just do a search on Facebook for Stuff to Blow Your Mind, or just put in blow the mind. That's our Facebook and Twitter handle.

Julie Douglas: And please drop us a line at blowthemind@howstuffworks.com.

Announcer: For more on this and thousands of other topics, visit howstuffworks.com. To learn more about the podcast, click on the podcast icon in the upper right corner of our homepage. The How Stuff Works iPhone app has arrived. Download it today on iTunes.

View Transcript here.

Topics in this Podcast: human psychology, Stuff to Blow Your Mind podcast, perception, Stuff to Blow Your Mind, robert, meditation