BIO 20 Lesson 1 Introduction

ASirulnik at Saddleback College
2.0K views • July 27, 2020

Introduction to BIO 20

0:00 hello and welcome to introduction to
0:02 biology
0:04 in this lesson you will be introduced
0:08 to some of the most fundamental concepts
0:10 of biology
0:12 and you'll be introduced to the process
0:14 of science
0:17 when you learn about biology you are
0:20 learning about the biology
0:22 of all living things there are
0:24 fundamental properties that are shared
0:27 by all living things for example
0:30 order order refers to
0:34 the patterned arrangements of
0:37 an organism's body or the patterned
0:40 events that occur within a cell for
0:43 example
0:44 think about the placement of your arms
0:46 and your legs and your head
0:48 this is the same for all humans
0:52 and the plant example you see here the
0:54 arrangement of the leaf
0:56 is the same for all members of this
0:58 species
1:01 reproduction is also part of life
1:04 for all living things reproduction
1:08 refers to the creation
1:12 of offspring that are genetically
1:15 similar to
1:16 although sometimes identical to the
1:18 parents
1:22 and a response to the environment
1:25 by responding to the environment an
1:28 organism
1:29 is able to avoid danger and find food
1:35 just as all living things are capable of
1:37 reproduction
1:38 so are all living things capable of
1:41 growth
1:42 growth is necessary for a newly produced
1:45 offspring to reach the size of
1:48 reproductive maturity
1:52 regulation another word for which is
1:55 homeostasis
1:57 refers to responding to changes in the
2:00 environment
2:01 such as responding to changes in
2:03 temperature
2:05 responding to the changes in how dry
2:08 or moist the environment is homeostasis
2:11 means maintaining a constant internal
2:15 environment even when the environment
2:18 itself
2:18 is changing all of these properties that
2:22 you've seen
2:24 reproduction growth homeostasis
2:28 order they all require that the organism
2:32 acquire and utilize energy
2:36 animals obtain energy from food plants
2:39 obtain energy from the sun
2:42 these processes of growth reproduction
2:46 homeostasis maintaining order they all
2:49 require energy
2:53 and the features you see that are
2:55 different
2:56 amongst different species on
2:59 our planet those differences are
3:02 adaptations
3:04 adaptations refer to traits
3:07 that a species has that allows it to
3:11 survive and reproduce successfully
3:14 in its particular environment
3:18 and finally all of those properties of
3:21 life that you have seen
3:22 so far reproduction responding to the
3:25 environment etc
3:28 these are shared amongst all living
3:32 things on earth because of the
3:36 shared ancestry that all life has
3:40 that shared ancestry is referred to as
3:43 the
3:43 unity of life
3:48 each species is unique from one another
3:53 and individual members of a species
3:57 are often unique from each other as well
4:00 that uniqueness is referred to as the
4:02 diversity
4:03 of life the diversity of life
4:07 as well as the unity of life is
4:10 explained by the process
4:12 of evolution evolution is the process
4:17 by which the features of particular
4:20 species
4:21 change over time
4:25 when we talk about biology we can
4:28 discuss biology at many different levels
4:31 we can talk about biology at the most
4:34 fundamental level of life
4:36 individual atoms or we can talk about
4:38 biology
4:39 from the largest perspective of life
4:42 called the biosphere
4:44 these different levels of organization
4:47 are known as the hierarchy
4:48 of organization
4:52 at the very smallest level is an atom
4:57 individual atoms make up molecules
5:04 an organelle refers to a structure
5:07 inside a cell
5:08 and organelles are made of molecules
5:12 individual cells are made of organelles
5:17 a tissue is a structure made of
5:20 multiple cells of the same type
5:24 an organ may be made of multiple tissues
5:29 an organ system may be made of multiple
5:32 organs
5:33 and an organism is made of
5:38 multiple organ systems
5:41 so for example going to the example of
5:44 the fish you see here
5:47 individual atoms such as
5:51 carbon hydrogen oxygen make up the
5:55 molecules
5:56 of the fish such as the
5:59 protein and dna molecules
6:04 those molecules collectively make up
6:06 organelles
6:07 such as a nucleus
6:12 all of the organelles collectively
6:16 inside a cell make up a cell for example
6:20 we can have in the fish a muscle cell
6:24 or a nerve cell
6:27 multiple cells of the same type that
6:30 work together
6:32 are known as a tissue they're going to
6:34 be muscle tissue
6:36 nervous tissue an organ
6:39 is made up of multiple tissue types
6:42 for example the stomach is an organ the
6:45 heart
6:46 is an organ an organ system
6:49 is made of multiple organs so for
6:51 example
6:52 the circulatory system is made of
6:56 the organ which is the heart the organs
6:58 which are the blood vessels
7:01 the organism is made of multiple organ
7:03 systems
7:04 such as the circulatory system and the
7:07 digestive system
7:08 and the nervous system
7:12 a population refers to
7:15 a group of organisms that are
7:19 interacting and breeding with one
7:21 another
7:22 breeding with one another is a really
7:24 important feature of defining a
7:26 population
7:28 because of the shared gene pool
7:31 the shared genetics they have
7:36 a community refers to many
7:39 populations of different species
7:42 so for example we may have this species
7:46 of fish
7:47 and this species of fish as well as the
7:50 non-fish
7:52 such as this mangrove plant and this
7:55 bird and these birds all of these
7:58 different species
7:59 living together make up this community
8:04 an ecosystem refers to
8:07 all of the living things the bird
8:10 the plants and the non-living parts
8:15 of this habitat the water
8:18 the air the nutrients
8:22 and then finally the biosphere the
8:25 biosphere refers to
8:28 all of the ecosystems on the planet
8:31 and we reference the biosphere because
8:35 different ecosystems
8:37 far away from one another on the planet
8:40 actually
8:41 interact with one another because of
8:44 air flow and currents there
8:48 is an effect that can be seen
8:51 between ecosystems far apart from one
8:54 another
8:58 organisms can be grouped together
9:02 according to how closely related to one
9:05 another they are
9:06 the largest such groupings is known as
9:09 the
9:10 domain there are three domains of life
9:14 and they are bacteria archaea and
9:17 eukarya all members of
9:21 the domain bacteria are more closely
9:24 related to one another than
9:26 they are to either of the other two
9:29 domains
9:30 likewise all members of archaea are more
9:33 closely related to one another
9:35 then to either of the other domains and
9:38 all members
9:39 of the domain eukarya are more closely
9:41 related to one another
9:43 than they are to either of the other two
9:46 domains
9:49 there are some fundamental features that
9:51 are distinctive
9:52 of these domains
9:55 one feature is that bacteria
9:59 are made of prokaryotic cells
10:03 likewise archaea are made of prokaryotic
10:06 cells
10:07 but eukarya are made of eukaryotic cells
10:12 there are some fundamental differences
10:13 between prokaryotic cells
10:16 and eukaryotic cells
10:20 prokaryotic cells are simple
10:23 eukaryotic cells are complex and what
10:26 makes prokaryotic cells simple
10:28 is the absence of nuclei and the absence
10:32 of any other organelles
10:35 eukaryotic cells are more complex
10:38 because they have
10:39 nuclei and they have organelles
10:43 organelles are compartments within the
10:46 cell
10:47 a nucleus is one such compartment
10:50 you will learn about these organelles in
10:52 upcoming chapters
10:55 bacteria are characterized also by being
10:58 unicellular
11:00 that means an individual bacterial
11:03 organism
11:04 is made of just one cell archaea are
11:07 likewise unicellular
11:10 eukarya on the other hand has members
11:13 that are unicellular
11:14 and eukarya has members that are
11:16 multicellular
11:19 where these can be found well bacteria
11:22 can be found in
11:23 diverse habitats anywhere from the
11:26 inside
11:27 of the cells or organs of other
11:30 organisms to the soil
11:31 to the oceans archaea on the other hand
11:36 while their habitats are diverse they
11:38 tend to occupy
11:40 extreme habitats such as
11:43 very hot boiling hydrothermal vents
11:47 very cold frozen arctic glands
11:51 eukarya also inhabit diverse habitats
11:56 they inhabit the soils the oceans the
11:59 lakes
12:05 the domain eukarya
12:08 can be further broken down into kingdoms
12:13 there is the kingdom plantae the kingdom
12:17 animalia
12:18 and the kingdom fungi these are probably
12:22 the most familiar
12:23 organisms to you the plants
12:26 the animals and the fungi
12:34 there's another category in the domain
12:36 eukarya
12:37 that we call protists protists is not a
12:40 kingdom
12:40 protis is not any kind of classification
12:44 but it's a very general term that just
12:47 refers
12:48 to unicellular
12:52 eukaryotic cells or unicellular
12:55 eukarya
12:59 and there are some protists that are
13:02 closely related to the kingdom plantae
13:05 there are some protists that are closely
13:06 related to animalia and there are some
13:08 protists that are closely related to
13:10 fungi
13:17 biology is a science what it means to be
13:20 a science
13:22 is science is the process by which we
13:24 gain knowledge
13:26 in fact the latin root
13:29 of science scientia means knowledge
13:33 biology is a natural science
13:36 that means it is a science that relates
13:39 to
13:39 the physical world and the phenomena
13:43 and processes that occur in the physical
13:45 world
13:47 phenomena refers to the observations or
13:51 the events that we see
13:53 or detect and the processes refer to
13:57 how those events occur
14:02 the scientific method is a
14:05 step-by-step process by which we
14:09 gain knowledge the scientific method was
14:13 developed
14:15 to have a regular and predictable method
14:19 that scientists
14:20 are to follow such that we gain
14:23 knowledge
14:24 that we can have confidence in
14:27 confidence that it is
14:29 close to true
14:32 a hypothesis is how we begin the
14:35 scientific method
14:37 hypothesis is a suggested explanation
14:41 meaning what we think is causing
14:45 the phenomena that we observed or
14:49 how we think the process occurs
14:55 hypothesis is then tested using
14:58 an experiment very often
15:02 the results of the experiment do not
15:06 support the hypothesis if the results of
15:09 the experiment do not support the
15:11 hypothesis
15:13 then the scientists need to develop a
15:15 new hypothesis
15:17 if the results do not support a
15:19 hypothesis that's not a bad thing
15:22 it just means we are peeling away the
15:24 layers
15:25 to try to gain knowledge
15:30 when we use the phrase scientific theory
15:34 we are referring to an explanation that
15:37 has been proposed
15:39 in other words a hypothesis but has been
15:42 tested over and over and over again
15:46 with the same predictable results
15:50 such that we have a high degree of
15:53 confidence that we know the explanation
15:57 for the observation or we know the
16:00 process
16:01 responsible for the event
16:05 a scientific theory is as close as
16:08 scientists get
16:08 to true knowledge
16:12 the word theory is used differently by
16:14 people in common everyday conversation
16:18 in common everyday conversation we use
16:20 the word
16:21 theory more like how scientists use the
16:24 word hypothesis
16:25 for example you might say i have a
16:28 theory about why my friend was late
16:31 to dinner
16:34 but if you were speaking as a scientist
16:36 instead you would say
16:38 i have a hypothesis as to why
16:42 my friend was late to dinner
16:46 a scientific law is
16:50 a description of how elements of nature
16:54 will behave
16:55 under certain specific conditions
16:58 for example the law of gravity
17:02 or the speed of light is a scientific
17:05 law
17:12 science is a long and arduous process
17:18 science requires abundant observation
17:23 and going back to the drawing board over
17:25 and over and over again
17:31 inductive reasoning is one of the
17:34 methods
17:35 used in science to develop
17:38 conclusions
17:42 with inductive reasoning
17:46 we make observations
17:50 several observations
17:53 perhaps hundreds or thousands of
17:55 observations
17:57 and when we see the same pattern over
18:01 and over again
18:02 we can then arrive at a general
18:04 conclusion
18:06 an example i have illustrated here of
18:08 inductive reasoning
18:10 is this scientists have questioned
18:15 which part of the brain is stimulated by
18:18 music
18:21 a neuroscientist had an idea if we could
18:25 do
18:25 brain scans on people while they're
18:28 listening to music
18:29 we may see which part of the brain
18:32 becomes active when listening to music
18:36 the neuroscientists ask volunteers to
18:39 listen to music
18:40 and have brain scans and then
18:44 the neuroscientists needed also to have
18:46 volunteers have brain scans
18:49 while having no music
18:52 this way the neuroscientists could
18:54 compare the brain activity
18:56 while listening to music to the brain
18:58 activity while listening to nothing
19:01 and only then could they identify
19:05 which part of the brain was activated by
19:08 music
19:11 what these neuroscientists observed was
19:14 that the very same region of the brain
19:16 was active
19:17 in the volunteers who were listening to
19:19 music
19:20 and that same region of brain was not
19:23 active
19:24 when volunteers were experiencing no
19:26 sound
19:28 using inductive reasoning then the
19:30 researchers conclude
19:32 that that region of the brain that was
19:35 active while listening to music but
19:37 inactive when there was no sound is
19:40 activated by music
19:42 and it was named accordingly this region
19:44 of the brain
19:45 has been named the auditory cortex
19:50 auditory means sound
19:53 so using inductive reasoning the
19:56 scientists
19:58 saw the same pattern over and over and
20:01 over again
20:03 and drew a conclusion about the region
20:06 of the brain
20:08 activated by music
20:15 scientists also use deductive reasoning
20:20 deductive reasoning is almost like
20:23 the reverse of inductive reasoning
20:27 with deductive reasoning scientists take
20:30 a
20:30 general principle or even a law
20:34 to predict a very specific result
20:39 i will give you an example to illustrate
20:42 deductive reasoning
20:43 again using the auditory cortex
20:49 after the neuro scientists
20:52 had figured out that the auditory cortex
20:56 was the part of the brain stimulated by
20:59 music
21:00 this became a general principle
21:04 there were doctors who have reported
21:06 having patients who
21:08 hallucinate music that means they hear
21:11 music even if there is none being played
21:15 but they believe it's real
21:18 these doctors knew that the
21:22 auditory cortex is the part of the brain
21:25 stimulated
21:26 by music and therefore they
21:30 predicted that patients who hallucinate
21:33 sound
21:33 may have a problem with their auditory
21:36 cortex
21:37 meaning perhaps their auditory cortex
21:39 was active
21:40 even though there was no sound
21:45 so what these doctors did was they
21:47 predicted
21:49 that these patients will have activity
21:51 in the auditory cortex
21:54 and then the doctors
21:57 could proceed
22:00 with an approach
22:03 to dimming that activity
22:07 to try to help the patients not have
22:11 those musical hallucinations
22:25 science relies heavily on descriptive
22:28 science
22:29 descriptive science actually usually
22:32 does not begin with a hypothesis
22:34 but instead it simply begins with
22:36 observations
22:39 for example the neuroscientists
22:42 who sought to discover the area of the
22:45 brain
22:46 that would be active in people listening
22:48 to music
22:51 who asked the volunteers to have their
22:53 brains
22:54 scanned while listening to music or not
22:57 listening to music
22:58 the scientist observed the brain
23:02 activity the whole brain
23:03 the scientists did not have a hypothesis
23:06 about which part of the brain would be
23:08 active the scientists simply wanted to
23:11 observe where was it was it here was it
23:14 here
23:15 was it here was it here no
23:18 it was here this is descriptive science
23:23 describing what was observed
23:30 hypothesis-based science
23:34 is the science of
23:37 proposing an explanation and then
23:40 developing an experiment that can be
23:42 used to test
23:43 whether or not that proposed explanation
23:47 can actually explain the phenomenon
23:56 and hypothesis based science
24:00 comes after descriptive science
24:04 or is based on descriptive science so
24:06 for example
24:08 the neuroscientist had observed
24:11 elevated brain activity in the auditory
24:15 cortex that was descriptive science
24:18 but in order to have a more robust
24:23 set of data and have greater confidence
24:27 that this region of the brain was indeed
24:30 the region of the brain active in
24:33 people in general while listening to
24:36 music and not just the few people who
24:38 volunteered
24:40 the scientists needed a more robust
24:43 experiment
24:45 based on the scientific method
24:48 and so the science the scientists then
24:51 developed a hypothesis
24:53 and the hypothesis was that
24:57 when listening to music there would be
25:00 activity in the auditory cortex
25:04 when not listening to music there would
25:06 not be activity
25:07 in the auditory cortex and then to test
25:11 that hypothesis
25:12 the scientists needed to have lots and
25:15 lots and lots of volunteers
25:18 and the volunteers needed to be of all
25:20 different ages
25:22 men and women so that there wasn't any
25:25 kind of
25:25 bias as to what type of people had
25:28 activity in the auditory cortex while
25:31 listening to music
25:32 but instead testing the hypothesis that
25:35 people in general
25:36 have activity in the auditory cortex
25:39 when listening to music
25:49 we test hypothesis hypotheses
25:53 is the plural of a hypothesis we test
25:56 hypotheses
25:58 via the scientific method and the
26:00 scientific method
26:02 is a series of defined steps
26:06 that involves
26:09 experiments that are carefully designed
26:13 and observations that are carefully made
26:20 the scientific method begins
26:25 with an observation
26:28 such as
26:34 people respond to music
26:37 that's an observation or
26:42 the brain controls our responses to our
26:44 environment
26:46 that's an observation
26:51 and so the question that follows is how
26:54 does that work
26:55 why does that happen
26:59 and the next step is to form a
27:01 hypothesis that answers that question
27:06 the hypothesis would be
27:09 a proposed explanation or a proposed
27:13 answer to the question
27:17 the next step in the scientific method
27:19 is to make a prediction
27:21 based on the hypothesis such as
27:28 i predict that there will be activity
27:31 in the auditory cortex it volunteers
27:34 when they listen to music and there will
27:36 not be activity
27:38 in the auditory cortex when people are
27:40 not listening to music
27:45 i'll design an experiment i will have
27:49 hundreds of volunteers of all ages and
27:51 sexes
27:53 and i will randomly assign half of them
27:56 to listen to music
27:58 and half of them to have no sound around
28:01 them
28:02 and i will do brain scans of all of
28:04 those volunteers
28:07 i will analyze the results afterwards
28:10 the next step
28:10 after conducting the experiment is to
28:12 analyze results
28:14 meaning well how many of the volunteers
28:17 who listened to music
28:18 had activity in the auditory cortex and
28:22 how many
28:22 had activity when there was
28:26 sound and how many had activity when
28:28 there was no sound
28:32 if most of them had activity
28:35 when there was sound but no activity
28:39 in the auditory cortex during silence
28:42 then the hypothesis is supported
28:45 but if there's no pattern for example
28:48 what if i saw activity in the auditory
28:50 cortex sporadically here and there
28:52 regardless of whether there was sound
28:54 then my hypothesis would not be reported
28:57 sorry supported either way
29:00 the hypothesis has to be the results
29:03 have to be
29:04 reported even when the hypothesis
29:08 is not supported by the data those
29:11 results are important
29:13 knowing something knowing how something
29:16 does not work
29:17 knowing a particular explanation is not
29:20 accurate
29:21 is very very useful in science
29:26 the scientific method was developed by
29:28 sir francis bacon
29:32 this occurred about sixteen hundred
29:37 and the scientific method was a huge
29:41 breakthrough in the development
29:44 of the modern world
29:48 the scientific method gave us a means
29:52 of seeking knowledge
30:04 not every hypothesis is a good one
30:12 in order for a hypothesis to be one that
30:15 is
30:16 useful the hypothesis has to be
30:20 testable and falsifiable
30:25 what it means to be testable is there
30:26 has to be some kind of way of detecting
30:29 it
30:29 or ex or measuring there has to be some
30:33 tests that can be done
30:36 and falsifiable means there has to be a
30:40 conceivable method to show that the
30:42 hypothesis
30:43 is false so for example
30:48 here's an example of a non-falsifiable
30:51 hypothesis
30:52 in other words this is a bad hypothesis
30:56 cotton candy is delicious
30:59 we cannot falsify that the reason why we
31:03 cannot falsify that
31:05 is because there's no evidence that we
31:07 could possibly acquire
31:09 to show that it's false what could we
31:12 possibly measure to show that
31:16 cotton candy is not delicious why
31:20 because there's no way to test
31:23 for delicious there's no way to measure
31:27 delicious you can't count delicious
31:30 you can't do a chemistry detection
31:34 experiment
31:35 to detect whether delicious is in there
31:37 or not
31:39 there's no experiment that we could
31:41 design
31:43 where we could say it's not delicious we
31:46 can't conceivably falsify
31:48 it however
31:53 we could change this hypothesis
31:56 into one that is falsifiable
32:00 here is a falsifiable hypothesis
32:04 elementary school children are more
32:06 likely to report
32:07 that cotton candy is delicious compared
32:10 with adults
32:12 we can falsify conceivably
32:17 that elementary school children are more
32:21 likely to report
32:23 that it's delicious how we ask them
32:30 for this to be potentially falsified we
32:33 perform a test
32:34 a survey of opinion is an atta is a test
32:37 that we could do
32:40 here are the predictions we would make
32:42 from this hypothesis
32:45 again our hypothesis is that elementary
32:48 school children are more likely to
32:50 report that cotton candy is delicious
32:52 compared with adults
32:54 here are the predictions that we could
32:57 develop if there's no difference between
32:59 children and adults and the number of
33:01 individuals who report that cotton candy
33:03 is delicious
33:04 then the hypothesis is falsified
33:08 if more adults than children report that
33:10 cotton candy is delicious
33:11 then the hypothesis is also falsified
33:16 but if more children than adults report
33:18 that cotton candy is delicious
33:20 then the hypothesis is supported
33:33 when we test a hypothesis
33:37 we need to identify a variable
33:41 a variable is any part of the experiment
33:44 that can change
33:45 for example fondness for cotton candy
33:48 can change
33:49 people could be fond of it or not fond
33:51 of it
33:53 also the age of the person surveyed can
33:55 change
33:56 we can survey children we can survey
33:58 adults those are different
34:01 when we talk about variables some
34:04 variables are dependent
34:05 some are independent
34:09 and some are controlled
34:15 an independent variable is the one
34:18 that is hypothesized to have an effect
34:25 for example age
34:30 is the independent variable in the
34:33 cotton candy
34:34 hypothesis because age has an effect
34:38 at least in our hypothesis it does we're
34:40 hypothesizing that age
34:42 has an effect on fondness for cotton
34:45 candy
34:47 dependent variable on the other hand
34:52 is the variable that is hypothesized to
34:55 be affected
34:57 by the independent variable fondness for
35:00 cotton candy we are predicting
35:03 is affected by age
35:06 another way to think of it is fondness
35:08 for cotton candy where hypothesizing
35:11 is dependent on age
35:19 when there is a controlled variable
35:23 we're talking about a controlled
35:25 experiment
35:26 not all experiments are controlled
35:31 but when there is a controlled
35:32 experiment it means the researcher is
35:35 making changes intentionally to the
35:38 samples being tested
35:40 for example
35:46 if we are testing the hypothesis
35:49 that a certain medication can be useful
35:52 in treating a particular medical
35:54 condition
35:56 we need to provide the medication itself
36:01 as well as the control meaning
36:04 not the medication the placebo
36:08 the control is how we compare the
36:11 medication
36:12 to the non-medication
36:17 another example of a controlled
36:20 experiment is if we wanted to test the
36:22 hypothesis that plants
36:24 increase the growth rate when carbon
36:26 dioxide concentrations are increased
36:29 we have to control the experiment by
36:32 providing excess carbon dioxide to some
36:35 plants
36:36 and less carbon dioxide to others
36:40 another hypothesis that is an example of
36:43 a controlled experiment
36:45 is the hypothesis that insect pest
36:47 numbers
36:48 will increase if ladybugs are absent
36:52 if we have plants with ladybugs
36:56 we have to have a control plants without
36:59 ladybugs
37:01 and we compare the number of insect
37:04 pests
37:05 between the plants that have ladybugs
37:08 and the plants that do not have ladybugs
37:10 and we do that by adding or removing
37:13 ladybugs
37:16 when we are talking about controlled
37:18 experiments
37:20 we have an experimental variable
37:24 and a control variable
37:28 again a variable is the part that
37:30 changed
37:31 the control variable is the part
37:35 that remains unchanged
37:38 whereas the experimental variable is the
37:41 one that is changed
37:47 for example the control
37:51 variables would be in the first example
37:56 of where the hypothesis is that a
37:58 particular medication would be effective
38:00 for treating a
38:01 medical condition the control variable
38:04 would be volunteers who are given a
38:06 placebo instead of a medication
38:09 in the hypothesis that plants increase
38:12 their growth rate when carbon dioxide
38:13 concentrations increase
38:15 the control variable or the greenhouses
38:17 that have unchanged carbon dioxide
38:20 levels
38:22 and in the hypothesis that insect pest
38:25 numbers will increase if ladybugs are
38:27 absent
38:28 the control variable would be farms or
38:30 plants or plots
38:31 where ladybug populations are
38:44 undisturbed
38:59 it happens a lot that the hypothesis
39:03 is not supported by the data
39:07 usually these experiments do not make
39:11 the news and you don't hear about them
39:13 but the scientists do
39:17 and what does a scientist do when the
39:19 hypothesis is not supported
39:21 well they scratch off that hypothesis as
39:24 a proposed explanation
39:27 and they go back to the drawing board
39:30 and they develop another hypothesis
39:33 and they do that again and again
39:38 until the hypo they come up with a
39:40 hypothesis
39:41 that is supported by the data