#2 is grammatically incorrect if it stands alone; but people do use such forms in conversation. It could be seen as a short form of “Do you know why there is no sound in space?”
And thanks, Alan ) I understand what you mean and think the same way ) But I was confused because I often saw the phrases like the second one as the direct questions on many websites, internet communities, forums, comment sections (Youtube, for example), etc. Maybe it’s normal for internet conversations…
Thank you, Beeesneees. I understand you, but I was talking about the direct questions. It’s a very common situation (especially for Youtube) when some user leaves a comment with a direct question but it has a word order like an indirect one…
Btw, thanks again.
I see what you are getting at. It is a sort of ‘tentative question’ where the intonation/the way it is said, indicates that it is a sort of question and in written language is shown with a question mark although on the face of it, it is a statement.
Something like this? The full question would be: Is it something like this?