What’s the difference between a scientific law and theory? - Matt Anticole
-
0:08 - 0:11Chat with a friend about
an established scientific theory -
0:11 - 0:16and she might reply,
"Well, that's just a theory." -
0:16 - 0:19But a conversation about
an established scientific law -
0:19 - 0:23rarely ends with,
"Well, that's just a law." -
0:23 - 0:24Why is that?
-
0:24 - 0:27What is the difference
between a theory and a law, -
0:27 - 0:30and is one better?
-
0:30 - 0:33Scientific laws and theories
have different jobs to do. -
0:33 - 0:37A scientific law predicts
the results of certain initial conditions. -
0:37 - 0:41It might predict your unborn
child's possible hair colors, -
0:41 - 0:46or how far a baseball travels
when launched at a certain angle. -
0:46 - 0:50In contrast, a theory tries to provide
the most logical explanation -
0:50 - 0:54about why things happen as they do.
-
0:54 - 0:57A theory might invoke
dominant and recessive genes -
0:57 - 1:02to explain how brown-haired parents
ended up with a red-headed child, -
1:02 - 1:07or use gravity to shed light
on the parabolic trajectory of a baseball. -
1:07 - 1:08In simplest terms,
-
1:08 - 1:13a law predicts what happens
while a theory proposes why. -
1:13 - 1:16A theory will never grow up into a law,
-
1:16 - 1:20though the development of one
often triggers progress on the other. -
1:20 - 1:26In the 17th century, Johannes Kepler
theorized cosmic musical harmonies -
1:26 - 1:29to explain the nature of planetary orbits.
-
1:29 - 1:33He developed three brilliant laws
of planetary motion -
1:33 - 1:37while he was studying decades
of precise astronomical data -
1:37 - 1:41in an effort to find support
for his theory. -
1:41 - 1:43While his three laws
are still in use today, -
1:43 - 1:49gravity replaced his theory of harmonics
to explain the planets' motions. -
1:49 - 1:51How did Kepler get part of it wrong?
-
1:51 - 1:55Well, we weren't handed
a universal instruction manual. -
1:55 - 2:00Instead, we continually propose,
challenge, revise, or even replace -
2:00 - 2:04our scientific ideas
as a work in progress. -
2:04 - 2:05Laws usually resist change
-
2:05 - 2:09since they wouldn't have been adopted
if they didn't fit the data, -
2:09 - 2:15though we occasionally revise laws
in the face of new unexpected information. -
2:15 - 2:19A theory's acceptance, however,
is often gladiatorial. -
2:19 - 2:23Multiple theories may compete
to supply the best explanation -
2:23 - 2:25of a new scientific discovery.
-
2:25 - 2:26Upon further research,
-
2:26 - 2:31scientists tend to favor the theory
that can explain most of the data, -
2:31 - 2:35though there may still
be gaps in our understanding. -
2:35 - 2:38Scientists also like
when a new theory successfully predicts -
2:38 - 2:41previously unobserved phenomena,
-
2:41 - 2:45like when Dmitri Mendeleev's theory
about the periodic table -
2:45 - 2:48predicted several undiscovered elements.
-
2:48 - 2:51The term scientific theory
covers a broad swath. -
2:51 - 2:55Some theories are new ideas
with little experimental evidence -
2:55 - 2:58that scientists eye with suspicion,
-
2:58 - 3:00or even ridicule.
-
3:00 - 3:01Other theories,
-
3:01 - 3:05like those involving the Big Bang,
evolution, and climate change, -
3:05 - 3:08have endured years
of experimental confirmation -
3:08 - 3:13before earning acceptance by the majority
of the scientific community. -
3:13 - 3:16You would need to learn more about
a specific explanation -
3:16 - 3:20before you'd know how well
scientists perceive it. -
3:20 - 3:24The word theory
alone doesn't tell you. -
3:24 - 3:25In full disclosure,
-
3:25 - 3:28the scientific community has bet
on the wrong horse before: -
3:28 - 3:29alchemy,
-
3:29 - 3:31the geocentric model,
-
3:31 - 3:32spontaneous generation,
-
3:32 - 3:34and the interstellar aether
-
3:34 - 3:39are just a few of many theories
discarded in favor of better ones. -
3:39 - 3:42But even incorrect theories
have their value. -
3:42 - 3:46Discredited alchemy was the birthplace
of modern chemistry, -
3:46 - 3:48and medicine made great strides
-
3:48 - 3:53long before we understood the roles
of bacteria and viruses. -
3:53 - 3:57That said, better theories often lead
to exciting new discoveries -
3:57 - 4:01that were unimaginable
under the old way of thinking. -
4:01 - 4:04Nor should we assume
all of our current scientific theories -
4:04 - 4:07will stand the test of time.
-
4:07 - 4:11A single unexpected result is enough
to challenge the status quo. -
4:11 - 4:15However, vulnerability to some potentially
better explanation -
4:15 - 4:18doesn't weaken
a current scientific theory. -
4:18 - 4:23Instead, it shields science from becoming
unchallenged dogma. -
4:23 - 4:27A good scientific law
is a finely-tuned machine, -
4:27 - 4:29accomplishing its task brilliantly
-
4:29 - 4:32but ignorant of why it works
as well as it does. -
4:32 - 4:37A good scientific theory is a bruised,
but unbowed, fighter -
4:37 - 4:42who risks defeat if unable to overpower
or adapt to the next challenger. -
4:42 - 4:43Though different,
-
4:43 - 4:48science needs both laws and theories
to understand the whole picture. -
4:48 - 4:51So next time someone comments that
it's just a theory, -
4:51 - 4:54challenge them to go nine rounds
with the champ -
4:54 - 4:56and see if they can do any better.
- Title:
- What’s the difference between a scientific law and theory? - Matt Anticole
- Description:
-
View full lesson: http://ed.ted.com/lessons/what-s-the-difference-between-a-scientific-law-and-theory-matt-anticole
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.
- Video Language:
- English
- Team:
closed TED
- Project:
- TED-Ed
- Duration:
- 05:12
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Jennifer Cody edited English subtitles for What’s the difference between a scientific law and theory? - Matt Anticole |