One thing that I appreciate the textbook that I use for my Conceptual Physics class is that it spells out the basic foundations of how science ideas come to being. Yes, it does have the scientific method in the beginning, but what I am referring to is the difference between hypothesis, law, theory, and fact. When you ask the common public about these terms, chances are they would think that they are all similar, or they would not correctly understand a particular definition. This drives me crazy at times, because people tend to have this idea that if it comes out from science, it's something that doesn't change. Ask yourself this question: Have you EVER said these phrases before?


If you have said ANY variation of these phrases, then you don't understand these terms when you said them. In other words, you are wrong to say such phrases. Sometimes these understandings can be detrimental to the progression of science because they make this illusion that science is something that is solidified and can not be changed, when "change" is exactly what drives science in the first place. Science EXPECTS changes in our understand for the better.

Before I go on, it's time to tell the difference between these 4 words.

Hypothesis. Most people know this as an "educated guess." It means that you cannot just random guess something without any reason. There has to be some basis or knowledge beforehand to make such a guess. Another important part of an hypothesis is that it HAS to be testable. This is the reason why in the scientific method that schools teach you, the hypothesis is near the beginning of that process, because you would need to test that hypothesis.

For example:
This is a hypothesis: "The moon is made of cheese." This is testable. If we get a moon sample, and compare it with the material of cheese. If they are the same, then the hypothesis is true. If not, then the hypothesis is disproven.

This is NOT a hypothesis, but speculation: "Humans will never reach the core of the earth."

Law. A law is actually a statement or a hypothesis based on patterns and observations of the real world. Laws tend to be defined by equations in physics, relating two or more variables together. 

For example:
The Ideal Gas Law relates Pressure, Volume, and Temperature together (PV=nRT)

Theory. A theory is an idea to overall explain phenomenons of the universe after doing repeated experiments and researched fact. A key word that scientists use along with theory is that it is a synthesis, or a combination of two or more ideas to make an overarching idea If Law is "how things work" then Theory is "why things work that way" 

For example:
The Law of Gravity depends on the mass of two objects and the inverse square of the distance between one another. (F = Gm₁m₂/r²)
The Theory of Gravity (currently) is that objects with mass/energy bends the fabric of space time, which cause objects that bend that fabric less to be attracted  to the objects that bend it more.

Fact. Finally, a scientific fact is something that is verified repeated through experiments and is commonly agreed upon by the majority of people. In order for something to be deemed a fact, there has to be experiments that are repeated to get the results that you expect and that it is agreed upon by the majority of the scientific community.

Now that we got those out of the way, here's the thing about these scientific ideas: They can change over time. Obviously, hypothesis can change because if you did an experiment and it didn't fit your hypothesis, then you would have to change your hypothesis in order to retest. Laws can change because when we see a consistent misfit in our law through observations, then we would have to change that law to fit both observations if there is still a pattern showing. Theories have been changing for centuries because of how much research have been done on a subject. Facts obviously change because we went from Aristotelian science to Newtonian science to Modern science. All of these were considered facts during their time. 

Perhaps the best example of how science has changed our understanding over time is the atomic theory. We went from debates on whether atoms exist or not, to describing atoms as a round thing with an empty shell, to discovering the nucleus, to discovering positive and negative charges within the atom, to Bohr's model, to quantum orbitals. So from this we can see that a theory has been tested for a period of time and continuously studied, but as more results come in, a theory needed to either be corrected or updated for the better. Does this mean that we should ignore theories, like the phrase "it's just a theory"? No. Theories are well established ideas based on the observations and experimentation that support them, so being a theory in the scientific world means that it is deemed as the updated and currently most correct understand of the universe based on the observations made, so if there are no immediate challenges to that theory, that is the best possible understand of the topic, so it should not be taken lightly.

So with the scientific ideas that we have today, do we expect them to possibly change or update themselves in the future? The answer is yes. We don't have all the answers and just like the movement from Classical Mechanics to Quantum Mechanics, what we understand now might be limited to where we are or what we observed, so I wouldn't be surprised if there is a new discovery or a new result that would force us to develop a different but more correct way in understanding how things work. Science will never get us all the complete answers, but it demands change.

Thank you play, I once did this at school but, not as detailed as it is on this thread...it helped me to understand a bit more of the knowledge that I need, and to know more as well. ^-^

So basically, nothing is absolute? For some reason, I had this idea that laws and facts were. Now I can get that assumption out of my head.

Mistress : Well, no. There are such things as absolutes. That goes to the ideas of philosophy and logic. Science doesn't prove things right, but logic does. But yes, laws and facts may change. Now, is it possible that you got the most correct law or the most correct fact? Possibly, but you'll never know through science. The best thing that science can do is to keep testing and keep testing and hope that it gets similar results. If you get different results consistent, that might be a counterexample to prove a previously perceived fact to be wrong.

A lot of facts can depend on how we see the world, like how Pluto was a planet, but later Pluto is no longer a planet. We see that facts do change.

The good thing about laws and facts is that if they are heavily supported with no counterexamples or contradictions, it's ok to go with it. We do have some laws that have withstand the test of time for a long period of time or have only taken minor changes or tweaks.

So where does the statement that, Matter can be neither created or destroyed, fit?  Is it a law or fact or theory?  My question really is how is it any of these?  I see matter everywhere, if it can't be created then how did it get there? 

play4fun :

Well, I think that pluto has always been what it has been as far as what makes it up in materials. Although the definitions that we use can change, or become more precise.

I hope I don't come across wrong, but even when I'm listening to people I really trust talk about something, my mind is constantly testing everything that is said and seeing how true a statement, or idea is, and I have a question.

Why is this phrase wrong?

"Oh, well, it's just a theory, so I don't have to take it as true."

I mean, there are lot's theories out there, but they are often just as false as a hypothosis, being a theory does not mean that you have to accept it as true. There are many contradicting theories out there.

(I hope I'm not being to disruptive)

Sword legion : You don't have to accept it. That is not the point. What is wrong with that phrase is that you are, in a sense, putting theory on the same level of hypothesis. They are completely different. Saying "It is just a theory" shows that you have no true grasp of what 'theory' is in the science world. Gravity itself is a theory. So if you use the statement "It is just a theory" as a reason for not accepting something, then you must be willing to put that same logic to gravity, because the theory of gravity holds no more power than any actual accepted theory in the science community. 

rcarter2 :

Okay, thank you for telling me that.

I understand the difference between a hypothosis and a theory, but, I still say that no one has to believe something just because it is a theory.

Sword legion : Well, nobody really has to believe anything period. There is still a well known group that insists the Earth is flat. With free will, everyone is allowed to believe or disbelieve anything that they want.

I had to go back and read your thread, and I have to admit it's very well written. I never struggled with the terms myself, but I don't know that I ever gave deep thought to their meanings.  I do have a question for you though... which may be stupid...

Is there a scientific term for an 'untestable' guess, such as the one you provided (Humans will never reach the center of the earth)?

Also, since you started off with these terms, do you think you can write us an article on the proper way to set up a scientific experiment?  (With controls and all)?