In the scientific method how do you test a hypothesis?

Answer 1

1. Ask a question

2. Make a prediction

3. Plan and conduct an experiment

4. Communicate their results

Take this make-believe scenario: I am investigating the properties of water, and I need to know all I can about how water, ice and heat interact. I know that when water gets cold enough, it freezes, and that when ice is exposed to heat, it melts. I might come up with a hypothesis-- a first attempt to understand what is happening with water and ice. I hypothesize: Since water is the liquid state of H2O, and liquids are warmer than their solid forms, water must be warmer than ice. It must be that as soon as water forms from melting ice, it is at least a little warmer than the ice. After all, at zero degrees water becomes ice. At this point, I do not know for sure, but I am speculating (hypothesizing) based on the general information that I have. I wonder how I can test my hypothesis: Let us assume that I can measure the temperature of ice and of water with great accuracy. I should be able to easily make a mixture of ice and water, while measuring the temperature of each independently.

• If my hypothesis is correct, I will find that at one atmosphere of pressure and in a chamber kept at exactly zero degrees Celsius the ice will warm to zero degrees Celsius and it will get no warmer. When it is warmer, it is water and not ice.
• I will also observe that the water will be at least a little above zero degrees Celsius when it first melts away from the ice.
• I apply heat to the ice and some ice melts.

To my surprise and annoyance, I find that the water is exactly zero degrees Celsius. We have a problem. My fellow engineers need an answer, and I've been hyping my hypothesis all over the place. Eureka! I have found it! Keeping the chamber at zero degrees is the problem; as soon as the ice melts, the chamber air starts to cool the water, and it must also be cooling the thermometers, leading to an experimental error in the readings! I'll keep the chamber at 5 degrees Celsius. I go back to the lab and I notice that my containers now all have a mix of ice and water, and the chamber is at exactly zero degrees Celsius. Not only that, all the ice is now at zero degrees Celsius, and so is the water! Exactly! Now I am just plain confused. I leave the chamber exactly as it is for several days and nothing changes. Everything in the chamber is verified to be at zero degrees Celsius, water is not in the process of freezing, and the ice is no longer melting. It just all stays in equilibrium. If my hypothesis were correct, there would be no water in the chamber, because supposedly at zero degrees Celsius all water is ice, and water is always at least a little above zero degrees. My hypothesis has tanked; time for a new one. I wonder and wonder, and spend a few sleepless nights. Then I realize-- it has something to do with heat; it must. It has something to do with adding or with taking away heat... Hmmm. Testing a hypothesis is something like that. You wonder, and you explore. There is no fixed formula for always coming up with the right hypothesis or the right way to test it. Think about it; if there were such a formula, then all the questions along with all the right answers would be derivable from the formula alone. No such thing. [This would not be analogous to the Theory of Everything.]

Answer A hypothesis is tested by designing an experiment to prove or disprove it. The new Hadron Collider is trying to prove or disprove several hypotheses. One is that there is a particle called the Higgs boson. So watch out for the results.

Answer 2

A hypothesis is tested by performing the appropriate experiments. There are many possible approaches to this. In general, experiments are set up to allow an outcome that exposes the hypothesis as false. Advocates of the hypothesis hope that this outcome does not happen, and opponents of the hypothesis hope that it does. Below is one famous example. See Discussion for a more recent one.

Louis Pasteur lived at a time when many believed in spontaneous generation, the idea that living things could basically spring up out of nowhere. People observed that maggots 'sprang' to life in meat that was left to rot. Many other kinds of life could be seen 'forming' where before there could be seen no evidence of life.

The Swan Neck Flasks. He thought of a way to test this, and his experiment is widely taught as a wonderful piece of science. He put a nutrient rich solution into glass flasks and then using a flame he drew the necks of the flasks into "S" shapes. The result resembles the appearance of 'traps', like the traps just under the sinks in your home.

Then he boiled the liquid in the flasks, leaving some liquid in the flasks when finished. This killed any microbes inside the flasks, or so Mr. Pasteur believed. When the steam in the flasks began to condense, liquid formed in the neck curves, sealing off the liquid inside. No matter how long he waited, nothing grew inside any of the flasks. But when he broke off the neck of a flask, or tipped one so that the solution inside touched the liquid that condensed in the trap, then things began to grow in the solution. The untouched flasks remained microbe free.

Pasteur's opponents would have been happier if microbes had grown in all the flasks, suggesting that Pasteur's idea of living airborne microbes was as nutty as it must have seemed to them. But no one could escape the conclusion that no life was spontaneously springing from the boiled and sealed solutions, and after contact with the air or contaminated condensation, the solutions were teeming with life.

See Discussion for another more recent example.

Answer 3

They plan their investigation, make it fair etc. After they've found the results they probably; to double check this, do the whole thing over again, if this brings them to their results they've found the first time, they are right.

Answer 4

with an experiment, usually a controlled one which means one variable is manipulated and the others remain constant.

Answer 5

Experiments