What’s the difference between a scientific law and theory  - Matt Anticole - video Dailymotion

TED-Ed

Chat with a friend about an established scientific theory, and she might reply, “Well, that’s just a theory.” But a conversation about an established scientific law rarely ends with “Well, that’s just a law.” Why is that? What is the difference between a theory and a law... and is one “better”? Matt Anticole shows why science needs both laws and theories to understand the whole picture.  Lesson by Matt Anticole, animation by Zedem Media.

Transcript

00:00Transcription by CastingWords

00:08Chat with a friend about an established scientific theory,

00:11and she might reply,

00:13well, that's just a theory.

00:15But a conversation about an established scientific law

00:19rarely ends with, well, that's just a law.

00:22Why is that?

00:24What is the difference between a theory and a law?

00:27And is one better?

00:29Scientific laws and theories have different jobs to do.

00:33A scientific law predicts the results of certain initial conditions.

00:37It might predict your unborn child's possible hair colors,

00:40or how far a baseball travels when launched at a certain angle.

00:45In contrast, a theory tries to provide the most logical explanation

00:50about why things happen as they do.

00:53A theory might invoke dominant and recessive genes

00:56to explain how brown-haired parents ended up with a red-headed child,

01:01or use gravity to shed light on the parabolic trajectory of a baseball.

01:07In simplest terms, a law predicts what happens,

01:10while a theory proposes why.

01:13A theory will never grow up into a law,

01:16though the development of one often triggers progress on the other.

01:20In the 17th century,

01:22Johannes Kepler theorized cosmic musical harmonies

01:26to explain the nature of planetary orbits.

01:29He developed three brilliant laws of planetary motion

01:33while he was studying decades of precise astronomical data

01:37in an effort to find support for his theory.

01:40While his three laws are still in use today,

01:43gravity replaced his theory of harmonics to explain the planet's motions.

01:48How did Kepler get part of it wrong?

01:51Well, we weren't handed a universal instruction manual.

01:54Instead, we continually propose, challenge, revise,

01:58or even replace our scientific ideas as a work in progress.

02:03Laws usually resist change since they wouldn't have been adopted

02:07if they didn't fit the data,

02:09though we occasionally revise laws in the face of new, unexpected information.

02:14A theory's acceptance, however, is often gladiatorial.

02:19Multiple theories may compete to supply the best explanation

02:22of a new scientific discovery.

02:25Upon further research,

02:26scientists tend to favor the theory that can explain most of the data,

02:31though there may still be gaps in our understanding.

02:34Scientists also like when a new theory successfully predicts

02:38previously unobserved phenomena,

02:40like when Dmitry Mendeleev's theory about the periodic table

02:44predicted several undiscovered elements.

02:48The term scientific theory covers a broad swath.

02:51Some theories are new ideas with little experimental evidence

02:55that scientists eye with suspicion or even ridicule.

02:59Other theories, like those involving the Big Bang, evolution, and climate change,

03:05have endured years of experimental confirmation

03:08before earning acceptance by the majority of the scientific community.

03:13You would need to learn more about a specific explanation

03:16before you'd know how well scientists perceive it.

03:19The word theory alone doesn't tell you.

03:22In full disclosure, the scientific community has bet on the wrong horse before.

03:28Alchemy, the geocentric model, spontaneous generation, and the interstellar ether

03:34are just a few of many theories discarded in favor of better ones.

03:39But even incorrect theories had their value.

03:42Discredited alchemy was the birthplace of modern chemistry,

03:46and medicine made great strides long before we understood the roles of bacteria and viruses.

03:53That said, better theories often lead to exciting new discoveries

03:57that were unimaginable under the old way of thinking.

04:01Nor should we assume all of our current scientific theories will stand the test of time.

04:06A single unexpected result is enough to challenge the status quo.

04:11However, vulnerability to some potentially better explanation

04:15doesn't weaken a current scientific theory.

04:18Instead, it shields science from becoming unchallenged dogma.

04:23A good scientific law is a finely tuned machine,

04:26accomplishing its task brilliantly,

04:29but ignorant of why it works as well as it does.

04:32A good scientific theory is a bruised but unbowed fighter

04:36who risks defeat if unable to overpower or adapt to the next challenger.

04:42Though different, science needs both laws and theories

04:45to understand the whole picture.

04:48So next time someone comments that it's just a theory,

04:51challenge them to go nine rounds with the champ

04:54and see if they can do any better.

05:06close your hands,

05:11close your eyes

05:12and see if they can do anything

05:13they might be doing anything.

05:15In aASE

05:16or even a third,

05:17you can see if they can do anything.

05:19And so you can see them

05:20who can respond to these things.

05:21And so,

05:23it is not enough to do anything.

05:25So I'll just do anything.

05:26Exactly thing.

05:27By going in a time,

05:28you can see how they can I do it.

05:29So I'll just do something.

05:31It's really good.

05:32I can't wait a minute.

What’s the difference between a scientific law and theory - Matt Anticole

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