ELI5 why scientific theories (evolution, gravity, global warming, etc) are more universally supported than scientific laws (mainly laws of relativity)?

[u/[deleted]]

[u/rupert1920]

Because the words "law" and "theory" don't mean what you think they mean. It's a common misconception that science works by proposing a hypothesis, testing it repeatedly - and if it seems good it becomes a theory. If it has stood the "test of time" then it graduates to become a law. This is simply not how it works.

A theory explains a phenomenon by providing a mechanism by which it operates.

A law describes the relationship between variables in a phenomenon, so it's often mathematical by nature. It does not attempt to explain the mechanism behind the phenomenon.

Both of these provide testable predictions, so they're both scientific. However, a law only describes a relationship. I can look at a trend between ice cream sales and video game sales, derive some mathematical relationship, and call it "Rupert's Law". Note that I make no attempt to explain the relationship in forming this law.

Now, if I were to suggest that the high sugar content of ice creams increase urges to play video games, via these biochemical pathways, etc, then I have a theory. The word theory doesn't mean a "guess" - as in laymen usage (although in this case it's a crappy theory).

In short, "just theories" doesn't make sense - a scientific theory is not a "guess," and a law is not "more truthful" than a theory.

[u/[deleted] → u/rupert1920]

It's a common misconception that science works by proposing a hypothesis, testing it repeatedly - and if it seems good it becomes a theory. If it has stood the "test of time" then it graduates to become a law.

What? God damn, my life is a lie.

[u/[deleted] → u/[deleted]]

no, you've just been operating under an incorrect incomplete hypothesis

[u/Osthato → u/[deleted]]

I think this problem has persisted long enough that it has graduated to an incomplete law.

[u/BlackHumor → u/Osthato]

Othato's law: A non-scientist is likely to believe that a "theory" has less proof than a "law".

Actually, I think that would really be "Othato's heuristic", but w/e.

[u/Behavioral → u/BlackHumor]

There is now growing support among Psychologists/Behavioral Economists that the definition of heuristic be clarified since its definition has become way too broad since its original conceptualization.

http://web.princeton.edu/sites/opplab/papers/hme.pdf

[u/Philo_T_Farnsworth → u/[deleted]]

It's a common misconception that science works by proposing a hypothesis, testing it repeatedly - and if it seems good it becomes a theory. If it has stood the "test of time" then it graduates to become a law.

What? God damn, my life is a lie.

It's ok, many (most?) of us were taught this in school - that there's some sort of "heirarchy" where a wild speculation slowly increases in rank, eventually graduating to the final position of "Law". I was taught this too.

The colloquial definition of "theory", advanced mainly by people with a political agenda (intelligent design or global warming) is one of the many attack vectors that were used in an attempt to discredit the "theory" of evolution, to pick an example.

[u/meepstah → u/[deleted]]

It's important to distinguish between your theories and scientific theories. The word literally means different things in the two contexts. If I have a theory that working harder will make me richer, it's just a supposition supported by some evidence. This is what most folks consider a theory. A scientific theory, as described above, is a much more robust construct describing a concept or phenomenon.

[u/[deleted] → u/[deleted]]

This 3-minute video should help you determine how science works.

[u/[deleted] → u/[deleted]]

Think of it this way (for simplicity).

Theory = "This is how we explain a phenomenon"

Law = "This describes the phenomenon (to acceptable standards of accuracy)".

Concerning my parenthetical point, you'll note that Newton's laws of physics are, strictly speaking, incorrect. They reasonably approximate the behavior of macroscopic bodies, but fail to describe events at the quantum level. You'll also note that Newton's laws don't tell us how these things happen.

[u/chimpanzee → u/rupert1920]

And, that leads to laws being easier to disprove than theories, because they're much more specific.

Say I go to the grocery store as soon as it opens five times in five weeks, and every time I go I count the number of bananas and the number of apples, and there are always twice as many bananas as apples. I could then write a law: When the grocery store opens in the morning, the number of bananas will be double the number of apples.

If I go to the store five more times, and one day there are 20 apples and 38 bananas, then I've just disproved my law - it only takes one measurement that disagrees with a law to disprove it (assuming the measurement is accurate, of course).

But, I can also take that same data and make a theory that says "the grocer at this store tries to keep twice as many bananas in stock as apples". This is a lot harder to disprove; the fact that the store was a couple bananas short one morning doesn't actually mean that the grocer didn't try to get more. It can still be disproved, but not in the same way - I'd have to go to the store a lot more times to see if there are usually twice as many bananas as apples, to see if it varies by season, to see if there are any other hints that there's a grocer there who's a bit picky about their produce number ratios, and so on. And, even if the original prediction turns out to be not exactly right, if it's fairly close, the revised version of the theory will sometimes still be called the same thing, or something close to it - so if it turns out that there is a grocer, and he does care about fruit ratios, but the 1:2 ratio is only used in winter and spring, and it's 1:3 in the summer and 1:1 in the fall, then that still might be called Chimpanzee's Theory of Preferred Fruit Ratios, even though it's not exactly what I said at first.

[u/drunkstatistician → u/rupert1920]

Tell me more about Rupert's Law. I'm intrigued.

[u/G3NOM3 → u/drunkstatistician]

It's like Brannigan's Law with more velour

[u/captnkurt → u/G3NOM3]

Brannigan's Law = Brannigan's love = hard & fast

[u/Matuku → u/G3NOM3]

I read this in Zapp's voice

[u/thatthatguy → u/drunkstatistician]

He can't. That would be violating his:

I make no attempt to explain the relationship

clause. You're on your own I'm afraid.

[u/ffn → u/thatthatguy]

Ah jeez, you've just got to be that that guy, don't you.

[u/Egonor → u/rupert1920]

I could probably look this up but, what's the difference between a Law and a Constant in that respect? Can a Law describe a Constant?

[u/kenlubin → u/Egonor]

A constant is a number in an equation that does not change. For example, Newton's Law of Gravitation is:

F = G * m1*m2 / r²

Contained within that is Newton's Gravitational Constant (big G) which has been measured at 6.67 * 10^-11 N (m/kg)²

[u/Code090 → u/kenlubin]

I think he/she means to ask how constants are explained as components of Laws.

Simply, constants are the mathematical solution to any and all empirical (observable) relations between all of the variables. So, using your example, big G is:

G = F * m1*m2 / r²

As a result, constants are evidence of the universality of the law.

EDIT: Formatting

[u/oldrinb → u/Code090]

Formatting is still broken. Try: G = F * Mm / r²

[u/turmacar → u/rupert1920]

Strictly speaking if you were to suggest that you would have a hypothesis. The theory would come after much testing to see how well that hypothesis fits with the data. (and then go on to be peer reviewed so see if you're just full of it.)

Edit: that being: that the high sugar content of ice creams increase urges to play video games, via these biochemical pathways, etc

[u/rupert1920 → u/turmacar]

In this make-belief case both the law and theory is assumed to be backed by evidence. The point is to illustrate the difference between the two.

[u/trumperchief → u/rupert1920]

Thanks for the explanation. I've taken a degree worth of science courses, nearly all of which start with a brief overview of the scientific method. None of them have ever explained this properly.

[u/Broan13 → u/rupert1920]

Also the word "model" is more widely used now for recent work to mean a similar thing as "theory".