Thinking like a scientistThinking like a scientist

Galileo Gallilei and his telescope

The goal of scienceThe goal of science To investigate and understand the To investigate and understand the

world around usworld around us To explain events in the natural worldTo explain events in the natural world To make useful predictionsTo make useful predictions

AIDSvirus

Orion nebula

Tools of a scientistTools of a scientist ObservationObservation- gathering information - gathering information

in an orderly wayin an orderly way SkepticismSkepticism- asking questions and - asking questions and

needing proof needing proof LogicLogic- interpreting data analytically- interpreting data analytically Collaboration-Collaboration- willingness to share willingness to share

ideas and work with othersideas and work with others

Spontaneous generationSpontaneous generation People believed People believed

that life could that life could somehow arise somehow arise from non-living from non-living thingsthings

A recipe for bees

1. Kill a bull in winter2. Build a shed3. Place the dead bullon branches inside the Shed4.Wait for summer. TheDecaying body of the bullWill produce bees

From the Romans, circa 8 CE

Redi and the Redi and the maggotsmaggots

People thought People thought that maggots that maggots (larval flies) arose (larval flies) arose from meatfrom meat

In 1668, F. Redi did In 1668, F. Redi did an experiment to an experiment to test this ideatest this idea

Redi’s experimentRedi’s experiment 3 sets of jars: one left open, one sealed 3 sets of jars: one left open, one sealed

with a lid, one covered with clothwith a lid, one covered with cloth

Looking at variablesLooking at variables

Controlled variablesControlled variables: both jars have meat, : both jars have meat, location and temp the samelocation and temp the same

Manipulated variableManipulated variable: gauze covering keeps flies : gauze covering keeps flies off the meatoff the meat

Responding variableResponding variable: whether maggots appear: whether maggots appear

Gravy is boiled.

Flask isopen.

Gravy is teeming with microorganisms.

Gravy is boiled and sealed

Flask issealed.

Gravy is free of microorganisms.

Spallanzani’s Experiment : microbes in gravy

In the 1700s, micro-scopes reveal theexistence of cellularlife

Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

Pasteur’s experimentPasteur’s experiment

In 1864, spontaneous generation was finally disprovedby this experiment

Knowledge in science is built upon the Knowledge in science is built upon the work of others.work of others.

Experiments must be repeatableExperiments must be repeatable Conclusions are made based on fact Conclusions are made based on fact

and logic, not popular belief.and logic, not popular belief. Science knowledge is always changingScience knowledge is always changing

Superconductors at low temperatures