THEORY,LAW,FACT

WHAT IS THE BASIC

ASSUMPTION OF SCIENCE?

Nature is OrderlyWith this assumption we can explain

phenomenon using scientific theories

SPEC

UL

ATIO

N

A speculation is a general statem

ent about nature that is constructed without fact (or enough fact)

Scientific speculation is a legitim

ate part of the scientific process that develops early ideas that are not yet robust enough to be a testable, falsifiable or worthy of being a m

ore formal

"hypothesis".

QU

ESTIO

NS

: What m

akes up a theory?

What is Speculation?

What is the difference between

a scientific law and a scientific fact?

What theories/facts/laws do you

know?

SCI

ENT

IFIC

FAC

T Amazing facts: D

id you know that

there are 206 bones in the adult hum

an body and there are 300 in children (as they grow

some of the

bones fuse together).

The longest living cells in the body are brain cells w

hich can live an entire lifetim

e.

The cosmos contains approxim

ately 50,000,000,000 galaxies.

There are between 100,000,000,000

and 1,000,000,000,000 stars in a norm

al galaxy.

Hydrofluoric acid w

ill dissolve glass

A fact is an objective,verifiable observation.It is the same everywhere.It can and has been,verified many times.

It is a statement intended to

explain a phenomenon.

How certain is a theory?

Many people say it’s a guess or

speculation, which is how standard English uses the word Theory

When a scientist speaks about a

theory it means som

ething com

pletely different:

HOW WOULD YOU DEFINE THEORY?

Scientific Theory:

An explanation of how

and why a

natural phenomenon behaves the

way it does that is confirm

ed by all available evidence such that it could be used to predict new

,as yet unobserved phenom

ena

SCI

ENT

IFIC

THE

ORY

Examples of Scientific Theory:

The theory of relativity: that the laws of physics are the sam

e for all observers

The theory of evolution by natural selection: that the observed changes in species occur due to non-random

selection of well adapted specim

ens over less well adapted specim

ens

The Big Bang Theory:that the universe began as an infinitely sm

all point that underwent expansion to form

the universe as we know it today.

AR

E THE FO

LLOW

ING

TH

EOR

IES OR

FAC

TS?

Some illnesses are caused by

microscopic organism

s. The germ

theory of illness.

That the planets in our solar system

orbit around the sun. The heliocentric solar system

.

That the Earth is round, and not flat, or som

e other shape. The round earth theory

That all matter is m

ade up of atoms.

The atomic theory of m

atter

Why are these “facts” still

considered theories?

They are indeed facts, but they still fit into

the definition of theory because they

intend to explain

HO

W

DO

YO

U

FOR

M A

THE

ORY

?

THE

ORYF

ACT

Most theories cannot ever

be transformed into fact.

A theory is a

general statem

ent intended to explain facts

EVOLU

TIO

N

The theory of evolution by natural selection

Evolutionfact

Scientists considered evolution a fact before Darwin proposed his theory of natural selection.

SCI

ENT

IFIC

LAW

A law is similar to a theory in that it can be used to make predictions, but is less general and tends to be more mathematical in nature.

EXAM

PLES O

F SC

IEN

TIFIC

LAWS: N

ewton’s Law

s of motion:

statements about how large

objects made of atom

s behave when m

oving at low speeds relative to each other.

The Laws of Therm

odynamics:

statements about entropy,

temperature, and therm

al equilibrium

.

Law of G

ravity: Every particle attracts every other particle with a force that is proportional to the product of their m

asses and inversely proportional to the distance between them

.

LAWS M

AY BE PR

OVEN

FA

LSE, SO W

HY D

O W

E K

EEP THEM

?Newton’s laws of m

otion break down when the objects are very sm

all or moving very fast

relative to other objects. Why

do we keep them?

Because in everyday world situations they are very good at predicting. Engineers use them

for designing sky scrapers and travel through space is possible because of them

even though they are not always correct.

Remem

ber also that most

laws have never been

proven to be false!

SUM

MA

RY:

A theory is constructed most of

all from facts.

Theories contain laws, but laws m

ean very little without facts.

Theories also contain logical inferences that talk about how we know what we know.

Accumulating all of these, the

scientist makes a general

statement to explain all the

evidence. Other scientists reaffi

rm the facts and use the

theory to make predictions and

obtain new facts.