Practice English Speaking&Listening with: How Does Do Science? │ Figuring out what's true

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Lets say if we have this many of something, well call itone”, and represent it

with this symbol. If we have this many, well call ittwo”, and use this this symbol.

If theres none. If theres a certain amount of something and that amount is

none many, well call it zero and use this symbol. This many, call it three. Duh duh

duh duh duh. If theres this many, well call it ten. And were all out of symbols.

So well just start reusing symbols. And so on. This is a way, we can represent quantities

with words and symbols. And we represent lots of properties with words.

Like redness. They can have shapes. Things can cold. Scattered or patterned. They can

be wooden or wet. Even though 2 things are shaped differently

and are made of different materials we may still call them by the same name because of

other characteristics. Things can have movements or behaviours. And

we can have descriptions that only come when were comparing or looking at multiple things.

Any characteristic, property, or concept that we think about something, we always also have

a word for it. …I thinkthat might not be right. You.

Try to think of something that exists, in a way that you cant describe with words.

If youre not talking... well know that idea was wrong.

When light bounces off an object, the light can be directed by a lens to form an image.

A lens in the eye does this and creates an image at the back of the eye, where we have

an array of neuron cells that detect the light and send the information on the image to the

brain. And its a similar story for your other sensory cells that pick up other stuff.

From there your brain tries to makes sense of the signals, classifying concepts and trying

to build a model of what its observing. I dont know how that works exactly. How

neurons connecting to neurons becomes conscious concepts like white duck jumping.

Should probably ask like a brainologist. But for now, lets say our goal is we want

the concepts or pictures that we build in our mind to be the same as the world outside.

We want to accurately recreate the universe or at least a part of it, into our brains.

We dont want to be wrong. How do we do it?

Well, observations are the start. If we want to know what the world is like, looking directly

at it, is really going to give us the best idea.

But at the same time theres a lot of signals that our sensory cells and brains have trouble

with. Like certain wavelengths of light and sound. Things that are too small. Or too far

away. Or too fast. It can be hard to see an individual part if theres too much stuff

going on in the background. If theres too much noise.

We can have trouble processing things even when theyre right in front of us. Like

a face with the eyes and mouth upside down. Goes fromhappy birthday Mr.President

tomy sister and mother are the same person”. The haphazard way our brains and senses evolved

to be wired didnt give us a perfect accuracy, perception or memory.

But we can use tools to detect things we cant detect. Microscopes for things that are too

small, telescopes for things that are too far away. A tool that bits of radiation and

plays a fun noise. And instead of trying to remember and communicate

properties by feel, we can have this thing we call a centimeter. Just count how many

centimeters are the same length as this other thing. And we can use whatever standard of

comparison we need. And we can try to always go slowly and systematically.

But some people, after theyve had the neurons in a part of their brain die, they may no

longer perceive faces. They may not be able recognize their friends and family, celebrities,

or themselves. They can still see eyes and noses and mouths, and describe their layout.

The signal about the light is still coming in. But the brain no longer classifies this

arrangement we call a face. In the end there may be a lot of things like

thisuseful classifications about the universe, that all of our brains cant conceptualize.

But the point because those signals coming into the brain from the sensory cells, are

the only way information can get into the brain. Observations are the only way of really

knowing what the universe is like But we can also, come to new ideas by playing

around with old ones. For example we call this many six, and this

many four. But we can also frame them together. Then what do we get? Well we already have

a word for that amount, we call that ten. Split it in half, how do we describe that?

Make a sort of square array out of it, can we describe that quantity?

OK, five times five equals twenty five, isnt an observation. Its more a play on our

definitions. Its a statement that according to our naming scheme, five times five, and

twenty five, refer to the same thing. Or lets say we notice that a parallelogram

always has the same area as a square. If the parallelogram always has the same base length.

And height. Then we can look at the squares and play around.

Go bushoomp, bushoomp, bushoomp. OK, taking what we knew we can come to a new

useful model without having observed it first. I dont think this is how they actually

found this equation but they could have. We can do something like: if everything that

we call a Flaggle is blue. And everything that we call a Beener is a Flaggle. If thats

the information that we know, then we should also be able to know that every Beaner is

blue. Even when theyre nonsense words, the new ideas we come to make sense. Because

its creating a world in our mind and seeing what we would absolutely have to observe in

that world, because of the rules that we set. So if we build our rules and definitions and

ideas based on observations, we can form new ideas and models that actually describe and

match the real world. OK this is deduction. But we cant always describe the world with

this much certainty. For example, if we start rolling this dice

and we put it in with our eyes closed or something. Theres no way we could ever know, ahead

of time, what face will turn up when we stop rolling it. What do we know?

There are 6 sides, Only 6 possibilities for what will be turned up. Perfectly cubed, perfectly

balanced. We dont have any reason to think one of the sides is going to turn up more

or less than the others. Lets represent the likelihood of each event

occurring as being a certain proportion of all the possibilities. Added together they

will equal 100%. In this case we think each one has an equal probability of occurring

so theyre just one sixth of one hundred percent.

So we might say, rolling a 3 has a probability of decimal one six seven. Or of all the things

that could happen, rolling a 3 is 16.7% of those possibilities. Or we would expect to

see a 3 about one sixth of the time. This is all we can do, we dont know whats

going to happen so we describe the possibilities. What are the odds of rolling a total of 3

when rolling 2 dice? Each dice has the six possibilities, their outcome is independent

of one another and we can get any combination between them. Each combination having an equal

probability of occurring. These are all the possible mutually exclusive dice rolls. So,

weve got these 2 ways of rolling a 3, of 36 possible rolls. There is a 5.6% chance

of rolling a 3. Anyways. Weve got observation and deduction

to form an idea about the world. And theyre good, you know theyre pretty good. But

this other way we can form an idea, is by guessing. Just imagine the way the world is.

Great! Why would we do that? I mean theres a lot of possibilities for

things that could be in this mystery box, only one of those possibilities actually is.

So why dont we just look? We can verify the thing thats in there, and falsify all

the other possibilities. Its because sometimes its useful not to wait for an observation.

Hear thunder? The last time we heard thunder it rained. Maybe thunder always comes before

rain and its going to rain. We better put away any horse meat we dont want to get

wet. We just saw Frank eat these mushrooms, and

now hes bleeding out the eyes. These mushrooms must cause bleeding out the eyes. Lets

say away from them. We do it because seems faster and safer. Our

guesses arent always accurate, in fact you could say theyre often not accurate.

For example the idea that: the stars and the sun circle the Earth, while the earth remained

stationary. Sure it looks like theyre swirling around us and it doesnt feel like were

moving. But at the time I think a lot of people were very opposed to other ways of modelling

the system. Or the idea that you can sweat out toxins

through your sweat. I dont know the observation that led to this idea, maybe that you smell

after eating certain foods. But it doesnt matter the substance, cyanide, sugar or water,

you can take a certain amount and its not going to hurt you. Its when you take to

much that it starts to cause damage. If we definetoxinas a substance that hurts

you then, “toxinisnt a class of chemical. A toxin is any substance you have too much

of. So detoxification would be sort of the recognition when theres too much of something

and excreting it. Which doesnt happen at the skin. Small amounts of some stuff does

happen to leak out with the sweat, but unlike urine and stool, sweat doesnt have a lot

in it. Its almost entirely water. And theres no specializing cells at the skin sorting

chemical or making things easier to excrete. Skin cells function mostly as a barrier.

How about the idea that theres this God named Thor behind those loud lights in the

sky so scary. We better sacrifice another horse.

Frank? Frank eats everything he sees. It may very well have been something else he ate

when we werent watching. OK, guessing in fine, Its us wondering

about the world. Its not the problem. The problem is assuming that we know. Not recognizing

that were guessing. Well often take the first idea that pops into our head and

treat it as though it were true. Or treat an idea as true because someone told it to

us. We all tend to do it. We all have trouble sayingI dont know”. Me, Im no

exception. Im pretty sure Im wrong more than Im right. Im probably wrong

in this video. But lets see what we can do.

Lets call a guess or hypothetical idea about the world: a hypothesis. It will either

match the world outside, or not match the world outside.

For us to know whether an idea is true, for us to verify it, we have to observe it directly

out there. Turn the made up idea into an observation. For us to know that its false, to falsify

it, we have to distinctly see the real world being inconsistent with the hypothesis.

But just because we can imagine something, doesnt mean we can see it. Some ideas are

unverifiable. For example, the idea that: “every time

we drop this pen, it will fall”. Its falsifiable, if we see the pen float or go

up or something, just one time. Well see that NO, the pen doesnt always fall. And

the hypothesis is wrong. But its not verifiable. That is theres

nothing we can see that will let us know that this idea is true. Even if every time weve

ever seen the pen dropped, it fell. The hypothesis wasntevery time weve seen it”,

the hypothesis wasevery time”. Every time will always include, the next time, in

the future where we cant observe it. So this specific idea will never be able to be

an observation in our mind. Seems like its stupid overly strict semantics.

but the point of it is we never want to confuse the feeling that were right, with making

the observations to actually know something. If the hypothesis was different. Every time

we drop this pen in this room today, it will fall. The boundaries of the idea have been

set and we can see within those boundaries. But a universal idea about the way the world

is has no boundaries. And we can never see it entirely.

But at the same time, the pen falling seems to be very consistent. And weve never see

something else happen. Maybe we treat it as though it were true, since its so universally

predictive. But remembering in the back of our mind, observations are the way that we

know stuff. And we cant literally see all of this idea.

Along these same lines an idea can be unfalsifiable. For example the idea, a squirrel that looks

exactly like this, exists somewhere. Somewhere on Earth lets say. Its verifiable. What

would we have to see to know it? Just have to see the squirrel. Well know it exists.

But its hard to falsify. We would have to see every inch of the planet, simultaneously

in case it moves around, and see no squirrel in all those places to be able to have observed

the absence of the animal. Which lets say is possible. Although maybe this is a bad

example. If weve never seen one, and weve never seen any signs of it. And we know that

animals almost never have 2 tails. You know the squirrel is mostly just a made up idea

We can talk about the low probability of its existence and ignore the idea until theres

some sort of observational basis for itand we probably should. But its just, this

isnt entirely falsifying the idea. We havent truly observed the squirrels absence.

Unfalsifiable ideas can be tricky. Even if an idea is unverifiable, if its falsifiable

you can at least eliminate stuff as you make observations and the hypotheses that are left,

are maybe left because theyre true. Maybe. With unfalsifiable ideas we cant eliminate

stuff. And the idea can stick around with little to no observational basis.

An idea isnt automatically right or automatically wrong just because we cant see it. Saying

its unverifiable or unfalsifiable is about the disconnect the disconnect between being

able to imagine something, and being able to observe it.

OK, some ideas are both, unverifiable and unfalsifiable. Theres nothing we can see

to know that theyre true and theres nothing we can see to know that theyre

false. For example, since your experience of the world is all controlled by your brain,

its possible your brain is really attached by wires to a computer or something and all

the reality you perceive is fake. Verifiable? Nope. You could even wake up, in your vat,

wires coming out of your nips. But that could still just be a part of the simulation. Falsifiable?

Nope. If its not true, everything would look exactly the same.

OK, its like a hypothesis about a that squirrel we had no observational basis for,

except we think the squirrel is also invisible. Its like a hypothesis about a God who has

the supreme power who could manipulate the world and our lives. But its only exerting

its will in mysterious ways that are indistinguishable from regular ways.

Or a hypothesis that the universe popped into existence 10 seconds ago and the only reason

we didnt notice was because all the atoms and light and our neurons and memory and everything

came to be in the exact shape and position they are now. It also may have happened a

year ago, or 6 thousands years ago. Again, not automatically right or wrong its

just we cant see it entirely. Our bodies may be being harvested for energy, while were

kept subservient within a simulation. But at least theres pie.

To summarize so far were wrong a lotand learnins real hard.

OK. Lets say theres this new disease, you get a big lump. But people have been saying

that eating carrots can make them smaller. And we want to know if its true or not

true. Basically weve got two incompatible hypothesis

and we want to know which one matches the world. You know if were in a world where

carrots do shrink lumps, how would that world look? What observations could we expect to

make. The problem with these are they are hard to

verify or falsify even on an individual level, because of the noise. Kind of like with Frank.

Just because we observed them eating carrots, and then observed some change in their lumps,

doesnt mean the carrots are causing it. Could be something else theyre eating or

something else going on in their life thats causing this.

Even comparing them against somebody who didnt eat carrots might not be much more help. Because

again we dont know what else is important and if carrots only had a small effect it

may be lost among the noise. So what else? While we dont know how important

the other factors are. Maybe if we sample lots and lots of people and put them into

two different groups, only feeding carrots to one of the groups, maybe all this other

stuff will average out? And then if we see a difference in the average lump size between

the groups, maybe we can attribute it to the main difference between them. The carrots.

Would be nice if we record or survey these other factors so we can check to see if theres

a relationship between these other stuff and lump size. And check to see if theres any

interactions. You know maybe carrots only shrink lumps when the person also eats broccoli.

Or something. Or better yet, have both groups eat the same things, have the same lifestyles

and be genetically identical clones so that we can be very sure that any changes we see,

are from the carrots. Although that could be really hard.

OK, two groups, measure lumps sizes before, measure again after some amount of time, feeding

carrots to one group the whole time but not the other. Lets say these are how much

each persons lumps have changed in size over the course of the experiment. And these

are the average lump size changes of the groups. On average, the carrots eaters lumps shrunk

more or grew by less. So carrots shrink the lumps? Carrots can help?

MaybeBut it could also be the noise from all the other stuff. Maybe carrots did nothing

and all these peoples lumps were going to shrink and grow for other reason and it

was just the random way we put them into groups that created these results.

What we can do to investigate that is to look at every possible combination we could have

made with these people, assuming nothing we did mattered. Kind of like what we did with

the dice. What were looking for is the probability

of seeing what we saw, assuming carrots do nothing.

Its like if rolled ten apparently normal dice. And we rolled a 10, we rolled all 1s.

What are the odds of that happening? Pretty low, theres only one way of rolling a 10,

and with ten dice theres 60 million combinations we could have got. If we were testing a hypothesis

that these are normal dice, you would expect to see rolls in the 30 to 40 range. Theres

loads and loads of ways of rolling those. Rolling all 1s is so unlikely that the hypothesis

that these are normal dice is probably wrong. Maybe these are loaded dice. Or maybe the

dice only have 1s on them, or maybe somebody used a camera trick.

So same over here. This is the range of possibilities for the differences between the groups assuming

carrots werent a factor. This would be if we had randomly placed people into the

groups like this. And over here if we have randomly put people

into the groups like this. And everything in between. And this is how likely each difference

was of being rolled. If we see a difference between the groups somewhere over in the middle,

it looks like it was just random. But if the difference between the groups was somewhere

over in this region somewhere, where under random conditions theres only a 5% chance

of seeing it, or better yet a 1% chance of seeing it, then maybe it wasnt random.

Chances are good that theres actually something going on.

Where does our experiment we did fall on here? Here. If carrots did nothing and this was

just random, then we shouldnt be that surprised seeing the results that we saw in our study.

The hypothesis that it was random is relatively likely.

Its not that this difference between the groups was so small that its just not important.

Its about all this variance were seeing. If our results instead of looking like this,

looked like this. Same average difference, but what are the odds of randomly putting

everybody whose lumps shrunk in one group, and grew in the other? Very low. Its like

rolling all 1s, carrots would almost certainly be an important factor. Actually they look

like the only factor. But in our experiment is it just the other stuff affecting lump

size, or do carrots have some small effect getting drowned out by the noise?

We cant tell for sure from the observations we made. And unfortunately we dont know

which hypothesis is true. But theres not a strong reason to think that carrots shrink

lumps. Lumps seems to shrink and grow more for other reasons. Or maybe not. 14 people

isnt really enough to get a good result. That was a lot of work. Definitely too much

work. Can we just trust what other people say about

the world? Like if the all-time greatest physicist says

the universe was born some 14 billion years ago after something called the big bang. Can

we just go with that? Maybe…. But not if thats all they tell us. We still

need to hear the observations behind the idea. A hypothesis doesnt suddenly become true

because someone really smart says it. We still need to go through it in our heads as well.

. Even if its just communicated to us. If we think theyve made a mistake or lied

in such a way that we could never find out by looking at their work, you know, they recorded

an observations wrong or something. Then we would want to see some other people

able to make the same observations. And Ive never heard of someone who was always right,

so even if we trust them we should be double checking.

It can be hard and slow, and full of uncertainty. But this is the process of learning new things,

the process of science. Maybe not a proper definition, but its about: building ideas

from good and thorough observations, acknowledging what we have and havent seen, what we can

and cant see. To try to get what we build in our mind, to match the universe we observe.

Our ideas are always changing, even the tools and equations we use to build ideas might

change, entire areas of study might end up being wrong. But the goal is same.

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