As far as I know, "det är" isn't inflected. It can mean "it is" as well as "they are", "those are" etc.
I agree, the thing is that in Swedish, we use det as a formal subject to introduce talking about something, regardless of the gender and number of that thing. The problem is that in English, you wouldn't want to say It is just theories.
What if it’s referring to previously-introduced things: Quantum mechanics is well-established, but string theory and quantum gravity are not. Those are just theories. Would this still count as a formal subject and use Det är…, or would it be De är… in this kind of context?
That's an excellent example of when you might use de. But having said that, det might still be more common even in that scenario.
Well, we accept "those", "it", "they", "this", "these"... just need an idiomatic option to put as the default. :)
"De" is definitely more correct. Swedes will often say "det", but since "teorier" is plural, "det" is incorrect, just like "It is just theories." would be incorrect in English.
I disagree. Read the comment by @Arnauti above. I consider it incorrect to say "De är bara teorier", it doesn't sound good unless you've already specifically talked about some theories before uttering this sentence.
I agree with you, unless it's explicitly stated what de refers to, it must be det. This is called a presenting construction, I wrote much longer about them here: https://www.duolingo.com/comment/9708920 – As a native speaker of Swedish, it's easy to forget that they really don't like using the It is construction for plural objects in English.
I see what you mean! Depending on context, they could both be correct/wrong. Since we don't know the context, both could be used. I still feel "de" is a closer translation to the English sentence though!
I really hate this sentence... As a scientist there's no thing as "JUST theories". A theory is a proven thought, while a hypothesis is an unproven thought.
For me, as a mathematician, I would consider a theorem a proven thought while a theory is more of a framework. So a theory is one way of looking at the world where you can have both theorems, conjectures and other things inside that framework.
The theory in itself can't be wrong, but it can be a bad model of reality.
Anyways, I agree, it's a weird sentence.
A theory is still speculation, even when it has been tested in experiments, and the expression "just a theory" suggests that further testing could expose flaws in the theory:
I disagree, as a philosopher I know the big bang theory is indeed just a theory, it may or may not be true. Same goes for relativity :P Either way, a theory is just a idea about the truth. The day we stop questioning is the day we are all doomed
Do you use the phrase 'i teori', in the same way as the English 'in theory'?
I think that transation This is jast theories. for example .. this is the apples in box . I think
The Swedish pronunciation for this exercise is atrocious. Den svenska uttal för denna övning är avskyvärda.
No it's not :P And you want to say "Det svenska uttalet i denna övning är avskyvärt" because "uttal" is neutrum and conjugates to -et or -t in related words (such as "den"->"det", "avskyvärd"->"avskyvärt") :)