0:07 you're listening to brains on from
0:08 American public media we're serious
0:11 about being curious I'm Molly bloom
0:13 there's an interesting trend happening
0:16 right now in kitchens at schools and all
0:19 over YouTube kids everywhere are making
0:23 homemade slime that stretchy you'll eat
0:28 Slurpee stuff to make it you just need a
0:31 few simple things like laundry detergent
0:33 and Elmer's glue in fact we've got a
0:35 video showing you one recipe at brains on.org
0:36 on.org
0:38 maybe you already know about this stuff
0:40 or maybe you don't but a lot of our
0:45 listeners are way into it well slime is
0:55 sticky stretchy imagine taffy but you
0:57 can play with it and it's much more
1:02 stretchy it's like how is it not so cool
1:05 to watch it gets spread across and I
1:07 like turning it over and over it looks
1:10 so cool and and you can add like
1:12 different colors and sparkles to it it's
1:18 really fun to play with that's Ashley
1:19 from Burke Virginia Charlie from
1:21 Rockville Maryland Ava from Los Angeles
1:23 California and Irene from Minneapolis
1:26 Minnesota and they are slime obsessed
1:29 today on brains on we are also slime
1:32 obsessed what is it and why do we like
1:34 touching and poking and squeezing it
1:43 let's find out today's episode was
1:45 inspired by this question hi my name is
1:47 Eva I'm 11 years old from Los Angeles
1:50 California I love to make slime my
1:53 question for brains on is how does
1:55 sticky glue becomes slime when you add
1:57 laundry detergent yeah what is happening
2:00 when you make slime ah this is a great
2:01 question to help us find an answer we
2:03 called up Rachele Burks she's an
2:05 assistant professor of chemistry at st.
2:07 Edwards University in Austin Texas I
2:09 have a PhD in chemistry and a master's
2:11 in forensic science and a bachelor's in
2:14 chemistry so I'm a big door
2:17 right there with you Rachel she told us
2:19 the magic starts when you add something
2:21 called sodium borate to water in laundry
2:23 detergent these are already mixed but
2:25 some slime makers do it themselves and
2:28 when you add that compound sodium borate
2:31 into water it makes an anion which is a
2:33 negatively charged compound
2:35 so remember molecules those tiny atomic
2:37 structures that make up well pretty much everything
2:38 everything
2:40 sometimes they interact with other
2:42 molecules to become a new compound
2:44 sometimes that compound is either
2:46 positively charged or negatively charged
2:48 it has to do with how many tiny
2:50 particles called electrons the compound
2:53 ends up with when water and borate form
2:55 a new compound that compound has a
2:56 negative charge
2:59 it also takes on a special shape I like
3:00 to describe it it is if you looked at
3:03 your hand you can turn it into a bit of
3:06 a cloth so you could grab stuff right
3:10 and that's what this ion does next this
3:13 grabby ion meets the glue and starts
3:15 grabbing glue is made up of something
3:18 called polymers these are just strings
3:20 of molecules bonded together rochelle
3:21 says you can think of a polymer like a
3:24 long rubbery spaghetti noodle
3:27 and so when glue is just glue it's just
3:30 a bunch of loose spaghetti noodles all
3:34 sliding past each other but once you add
3:37 in the borate compound you've added in a
3:40 bunch of claws and what that does is one
3:44 claw grabs one sticky glue polymer got
3:48 you another claw grabs another one and
3:51 that means that now two polymer strands
3:54 are actually connected through these
3:58 kind of a claw bridge I think I can't
4:00 get away that means that the polymers
4:03 can no longer be slippy and sliding past
4:05 each other they're actually connected
4:08 this happens all over the glue with all
4:14 of that boring and so it goes from being
4:17 little slippy slide a spaghetti noodles
4:19 to being like speck
4:21 the next day when it's left over and you
4:23 stick a fork in it and you pull it up
4:25 and it's one giant massive connected
4:28 dried-out spaghetti noodles that is what
4:30 is happening here
4:33 so borate is actually connecting these
4:36 polymer spaghetti noodles and clumping
4:38 them all together and giving us what we
4:42 call slime of course unlike a clump of
4:45 spaghetti you can't see the individual
4:46 polymer strands and slimes since they're
4:49 so small but it's this interaction
4:51 happening on the microscopic level that
4:53 gives slime its texture so now we have
4:55 slime which brings us to our next
5:04 question my question is what state of
5:06 matter is slime
5:09 solid or liquid it is what we like to
5:11 call it's got a really cool name after
5:14 Isaac Newton it's a non-newtonian fluid
5:17 non-newtonian to understand this let's
5:19 start with regular old Newtonian fluids
5:22 17th century scientist Isaac Newton
5:24 thought how well a liquid flows depends
5:27 on how warm or cold it is let it be
5:30 known the warmer the fluid the smoother
5:33 the flow the cooler the fluid that flow
5:37 be slow Newton out this characteristic
5:39 how thick or runny a liquid is is called
5:42 viscosity you can easily see this in
5:44 lots of common liquids like honey cold
5:46 honey is really gooey and thick but heat
5:48 it up and it's more slippery and more
5:51 runny so that is actually called a
5:53 Newtonian fluid when temperature affects
5:56 kind of how easily it moves well there
5:58 are these what are called non-newtonian
6:01 fluids where it's not just temperature
6:04 that affects them it can be like a force
6:06 like a shearing force like you pulling
6:07 on it or you poking at it
6:09 Rochelle Burke says for these
6:11 non-newtonian fluids pressure and force
6:14 actually change how runny they are how
6:17 they respond to the stress is different
6:20 so if you take slime and you can't get
6:22 really fast with a really high force you
6:24 can snap it right into like like
6:26 breaking a pencil run ain't like if you
6:28 just snap the solid but if you
6:30 took the same slime and you just applied
6:33 the same force but over a longer time
6:37 not that sharp application of force the
6:40 slime would just stretch like a big
6:44 piece of taffy candy so just how we
6:46 treat it gives us kind of different
6:48 properties that we're seeing sometimes
6:50 it acts like the liquid or like the
6:52 thick like a honey very viscous but
6:55 still all in one piece and sometimes we
6:57 apply a force and it snaps like we would
7:02 expect from a solid think of water it's
7:05 a classic Newtonian fluid if you throw
7:07 it against a wall well it splashes
7:09 everywhere that force doesn't change how
7:11 it behaves but if you threw slime
7:13 against a wall it would smack almost
7:16 like a solid but if you poured Syme
7:18 slowly into a bowl it would flow more
7:20 like a thick liquid that's classic
7:22 non-newtonian fluid behavior
7:24 Rochelle says slime isn't the only
7:26 non-newtonian fluid out there there are
7:28 others like quicksand or silly putty or
7:30 even something you might have in your
7:32 refrigerator a food item that's also a
7:35 non-newtonian fluid is ketchup it fits
7:37 in the bottle anyone's ever wrestled
7:39 with a ketchup bottle you know that it
7:41 can be a bear to get out of the bottle
7:44 but once you give it the right amount of
7:46 force it just moves straight out of the
7:48 bottle so it has some really interesting
7:51 properties when you apply just the right
7:54 force in just the right way so slime
7:57 this cool non-newtonian fluid happens
8:00 when 4/8 water and glue mix you can get
8:01 the borate lots of ways like using
8:03 laundry detergent or contact solution
8:06 some recipes call for borax which is
8:08 used as a cleaning product now an
8:10 important safety note this borax stuff
8:12 can sometimes irritate the skin so be
8:14 very careful if you decide to use it
8:17 check with your parents first don't rub
8:19 your eyes or face while playing with
8:20 slime and wash your hands when you're
8:23 done if you'd rather skip the borax
8:25 there are lots of recipes without it
8:27 online have your parents help you find
8:30 one and get creative add food coloring
8:33 or glitter while you're researching your
8:48 slime let's make slime try to make some slime
8:48 slime
8:51 let's make slime it's about as fun as
8:53 compete first let me tell you all the
8:55 stuff you'll need you'll need a big bowl
8:58 and a bottle of glue white clear or
8:59 glitter glue it's up to you you need
9:03 baking soda not baking powder so double
9:05 check it before you get started some eye
9:08 drops or contact solution a spatula or
9:09 something to mix now let's get to it
9:20 make slime yeah let's make slime now
9:22 open the tool and pour it all into the
9:24 bowl it's real sticky so don't lose
9:26 control now open the eye drops or
9:28 contact stuff put in a few drops taking
9:31 slope there's no rush I can do drip ten
9:33 drops of soap start mixing it in start
9:35 mixing it in okay
9:37 baking soda how much you need you never
9:39 know so start with a little and stir it
9:41 in as you go a few more eye drops a
9:44 little more baking soda in no time you
9:47 got slime now mix it up mix it up mix it
9:51 up mix it up yeah now pick it up pick it
9:53 up squish these in you're free good
10:05 mix it up yeah let's make slime yeah my
10:08 slime so cool my slime is so fun my
10:10 slime so weird man it blows my mind when
10:12 you're all done making the plan with
10:14 your slobs in a sandwich bag save it for
10:33 next time slime that song and slime
10:35 recipe comes from Steph Alexander a
10:37 rapper with the Doomtree collective he's
10:40 also a father and slime aficionado that
10:42 song is gonna be stuck in my head for
10:44 sure would you say it says sticky as
10:46 slime hey Sandin hey mark are you guys
10:47 here to talk about your next debate
10:49 yeah we've been flexing our mental
10:52 muscles practicing our pronunciations
10:55 elocution elocution we're ready we just
10:57 need the next topic we've argued which
10:59 are better bridges or tunnels we've
11:03 pitted fire against lasers and we've now
11:06 devout cats or the evil or just
11:08 misunderstood our next debate is about
11:11 well we don't know that's where you come
11:13 in we want to know what you'd like us to
11:16 tackle in our next verses episode is it
11:19 gonna be bears vs. Bobcats planets vs.
11:22 stars is cereal a soup what I mean think
11:23 about it right
11:25 soup is just a liquid with stuff
11:26 floating in it that's what cereal is
11:27 that's crazy
11:29 soup has some vegetables and yeah that
11:31 cereal has grains and you could argue
11:32 though whoa whoa save it for the debate
11:34 guys but yeah send mark and sand in your
11:38 ideas at hello at brains on org thanks
11:41 guys no problem Molly totally a suit not [Music]
11:43 [Music]
11:46 if you're a teacher interested in using
11:48 brains on in your class drop us a line
11:50 at that same email address hello at
11:52 brains on org put teachers list in the
11:54 subject line and we'll feed your lesson
11:56 plans with upcoming episode ideas not a
11:58 teacher no problem we still want to hear
11:59 from you
12:01 you can send drawings and questions that
12:03 same email address like Abe did from
12:05 Chevy Chase Maryland how I know old is
12:10 snakes smell food it comes my name is a
12:12 will answer that one at the end of the
12:14 show in our moment of um plus you'll
12:15 hear the latest group of inductees to
12:17 the prestigious and exclusive brains
12:22 Honor Roll are you listening to this in
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12:30 staying put we're really excited to
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13:03 an org
13:05 you're listening to brains on I'm Molly
13:08 bloom now let's get back to slime some
13:09 of you told us that the first time you
13:12 saw a slime was on social media in fact
13:14 videos of people playing with slime can
13:16 get hundreds of thousands of views why
13:18 are people so obsessed with watching it
13:20 and playing with it our chemistry friend
13:22 Rachelle Burks thinks maybe it has to do
13:24 with how weirdly slime behaves it
13:28 doesn't do what we expect it to because
13:30 we expect things to be either a liquid
13:33 or a solid we we usually don't expect
13:36 things to kind of exist in this middle
13:38 realm we also asked our slime experts
13:39 Ashley Ava
13:42 Charlie and Irene to weigh in after you
13:45 make it it's fun to feel and play with I
13:47 think it's fine to bank and everyone
13:49 doesn't think of some people think it's
13:51 stressful but I think it's like relaxing
13:54 and fun and you get a fun end product in
13:58 my opinion my mom used to say slime is
14:00 gross because of the sounds but I think
14:03 it's actually very relaxing and calming
14:05 it's actually just like a nice
14:07 consistency and it's satisfying in a
14:10 releases stress Charlie gave us another
14:12 explanation for why she thinks so many
14:13 people like watching slime videos I
14:16 think it's because of the ASMR I don't
14:18 know what it stands for but I hear
14:20 people say it and that's I think that's
14:22 why I people watch it because it sounds
14:26 amazing and satisfying ASMR what is that
14:29 we asked Nick Davis a psychology
14:30 professor at Manchester Metropolitan
14:33 University in the United Kingdom is Emma
14:35 which stands for autonomic sensory
14:37 meridian response which is a very
14:40 strange relaxing tingly feeling that
14:42 some people get that might be triggered
14:46 by calming things in their environment
14:50 like like having their hair touched or
14:51 something like that nick has studied
14:54 ASMR and he says it's sort of a calm
14:56 chill on your head or your spine some
14:57 people get it when their back is
14:59 scratched others get it from hearing
15:01 soft sounds like the faint crinkling of
15:10 maybe you know what ASMR is or maybe you
15:12 don't it doesn't happen to everyone but
15:14 Nick says people who get that tingly
15:15 sensation often get it from similar
15:19 situations a lot of people get triggered
15:23 by whispering sounds or people paying
15:26 close attention to them so if you are in
15:28 a situation like a haircut where
15:30 somebody gets very close to you that
15:32 seems to trigger people's sort of
15:34 relaxed tingly sensation and we also
15:36 found that the sorts of things that
15:39 triggered ASMR seem to be related to
15:41 feeling very comfortable in another
15:44 person's presence so it's like being
15:48 maybe when you're being cuddled by your
15:49 mother when you're very young it takes
15:53 you back to that sort of sensation
15:55 nick says his team has never studied
15:56 slime specifically but he thinks that
15:58 when people play with it it makes soft
16:00 sounds sort of like the sounds you hear
16:01 from someone's mouth when they whisper
16:03 in your ear for some people those sounds
16:07 trigger ASMR of course all of these
16:09 ideas are just theories they're sort of
16:11 educated guesses about why we might like
16:13 slime in order to get a solid answer
16:15 we're going to need more research if
16:16 you've got a theory about why people
16:19 love slime feel free to send it to us at
16:22 hello at brains on org is it the sound
16:26 the texture the colors let us know
16:29 and speaking of sounds we almost forgot
16:42 it's time for the here it is did you
16:44 catch that here it is
16:50 once more got your guests here's the
16:54 answer I'm Eli McGinnis I am 10 years
16:57 old that was the sound of my dad hanging
17:00 a wool football with a metal bat this
17:02 sound was recorded in my yard where my
17:04 family was playing baseball together I
17:07 don't plan a baseball team buy a lot of
17:10 hit baseballs in my yard our family I
17:13 like to use different kinds of bats like
17:16 plastic wood and metal and like to
17:18 compare the different sounds they make
17:22 thanks Eli play ball now before we end
17:23 we're going to give shout outs to the
17:25 latest group of brainiacs to join the
17:27 honor roll but first we're going to
17:29 answer Abe's question about how snakes
17:30 smell with their tongues it's our moment
17:39 of my name's Carroll Spencer and I'm a
17:42 staff curator of herpetology at the
17:43 University of California at Berkeley
17:45 it's a Museum of vertebrate zoology
17:48 herpetology is a study of amphibians and
17:51 reptiles and I take care of the
17:54 specimens we have here in the museum
17:58 snakes are actually great at snowing in
18:00 a couple different ways and they smell
18:03 fills our nose but the way they smell
18:05 with their tongues is they have an organ
18:08 in their mouth and so they can pick up
18:10 something with their tongue either
18:12 chemicals or little pieces of something
18:14 they're floating around the air on the
18:17 tip of their tongue and then it goes
18:18 into the top of the roof of the mouth
18:20 and actually touches this organ called
18:24 the vomeronasal organ and they are able
18:26 to sense the sort of taste and smell
18:32 using this organ tell the farmer or
18:34 nasal organ because it's right and
18:36 biting you bones and all the bomber and
18:39 the needle for humans are right in the
18:41 front your face but first make it on the
18:46 top of their head so they can sense
18:49 something to eat them or they can even
18:52 send their mates and so and the coolest
18:53 part button to me is that because they
18:55 have makes and wizards all that forked
18:58 tongue their tongue can actually sense
19:00 direction so they can tell us something
19:03 in front of them or on the side or and
19:05 apparently they use this a lot more than
19:10 whoa
19:13 snakes are cool and speaking of cool
19:15 here's the latest group of kids to power
19:17 the show with their drawings questions
19:20 and awesome ideas it's the brains on a roll
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19:38 Becca from Baltimore Addison and Elsie
19:40 from Jacksonville Florida Lucy from duit
19:41 Michigan kiya from
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19:46 from Petaluma California links and
19:48 Fisher from Hayden Colorado ELISA and
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19:54 Anna from Seattle Maya and Tolly from Montreal
19:54 Montreal
19:56 Kol and Owen from Arlington
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20:21 Dylan from Switzerland Xavier and Silas
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20:25 Erin from la Madeleine and Thomas from
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20:35 Washington thanks for listening and stay
