Think about it for a moment. Don't cheat by looking ahead.
When we talk about learning and knowledge and matters of faith and science, then these questions illustrate some important principles. Science is a human activity. Obtaining knowledge can be a tricky process.
Before 1982, doctors knew what caused ulcers. Too much acid caused ulcers, and usually as a result of stress. You might be a successful businessman, but if you had ulcers, it indicated something wrong with your mental health. Your stress might be caused by remembering your overanxious mother.
How did we treat ulcers? Antacids were the first line. Rest and relaxation was prescribed to help you reduce stress. Go on vacation -- but take the antacids with you in case you were too stressed there. If you can't handle the stress, change your job to something less stressful! And yes, psychotherapy would be in order. You just have to get that issue with your mother resolved.
So now we visit an Australian team of scientists who were looking at the corpses of people who had died from ulcers. They noticed that small, curve, rod-shaped bacteria were always found in the inflamed tissue, and the more inflamed the tissue was, the more bacteria was present.
This was rather a puzzler. First of all, they knew about this bacteria, H. pylori. You couldn't culture it. Besides, the stomach was an acid environment. Stuff that went into the stomach got digested. These particular stomachs especially. Lots of acid.
Still, that every corpse was infected with H. pylori was strange. So they tried culturing the bacteria, of course, without success. You just couldn't culture it. That is, until a culture sample was left for six days by accident, instead of the standard two days. So they discovered that the bacteria could be cultured after all, and that the bacteria grew slowly.
So now they could culture the bacteria. That was good. But there wasn't any proof that the bacteria caused the ulcers. Maybe the bacteria were able to infect the stomach because of the ulcer? After all, many people had H. pylori in their system, but did not have ulcers.
You see, medicine has rules for understanding disease. If you want to prove that an organism like bacteria causes a disease, there are some principles to follow. Koch's Postulates say that the organism should be found in the bodies of those with the disease (and not in the bodies of those without the disease). The pattern of infection should explain the lesions. So then, grow the germ outside the body, introduce the germ to a new, disease-free body, cause the disease, and see if the pattern of infections there explain the lesions. Neat and nice.
Except that this involves people. It is unethical to try to cause disease in a person. But the researchers believed they were onto something, so Marshall and anther volunteer ingested a culture of H. pylori.
That's right, they cultured a sample, put the bacteria in a beaker with water, stirred, and down the hatch. Feel free to be ill at the thought. But they did it!
In very little time, they had developed gastritis -- an inflammation of the lining of the stomach. At that point, they were well on the way to developing ulcers, but they took antibiotics to kill the infection they knew was there. They recovered and did not develop ulcers.
The researchers hadn't proven that H. pylori caused ulcers. They were close, but they stopped short of it. Still, their experiment suggested a new treatment for ulcers. Use antacids to lower the acid levels of the stomach, and use antibiotics to cure the infection. The results? For the first time, ulcers became curable.
Warren and Marshall eventually won a Nobel prize for their work. They had completely changed a medical paradigm. Instead of the "stress causes ulcers" notion, they substituted, "H. pylori causes ulcers. And if you have little beasties eating holes in your stomach, you are going to have stress, you betcha."
But even today you will hear people say that stress causes ulcers. Old "knowledge" is hard to replace, even when the new knowledge is so much better.
Which brings up a few things about how we know things.
First of all, we don't always know what we think we do. It pays to try different approaches, even if you fail with most of them. Yes, rules are still important, but you can use the rules to explore different ways to do things.
Creationists criticize science for changing. But change is what makes science so important. If you want to understand a problem, you have to follow the pattern of evidence. So what if you don't understand it all? Partial success is still success, and can be used to help you even further.
You learn things by doing, by trying, by pushing the envelope, and even by mistakes and serendipity. Just pay attention. Even the authorities are wrong from time to time. It makes sense to check things out.
Other things that brought about this learning were volunteering and collaboration. Scientists are pretty good at those things. They worked this problem hands-on, and they made a discovery that changed our world. We now know what causes ulcers, and we can treat them effectively. From once being a major cause of death, ulcers now rank as an annoyance.
What do you know? How do you know it? Are you so sure that you wouldn't be willing to have your mind changed if the evidence indicated it?
Learning is a human endeavor. Start exploring and see what you can discover, too.