Yeah what is truth? It is a good question and it is extremly hard to define it. Of course it is true that an apple is red but it is also true that an apple is green.
I had really long discussions with a friend of me.
I heard a truthworthy report is one that has at least three independant sources which all tell the same story. So far so good but who really checks the relation?
If you said something like mandala-stones have healing power and I say the same thing and then someone would find a third person that states the same, is it the truth then?
Other thruthes come down to how far can your imagination go. Your picture is a good example. I've heard that some peoole say that this was an ancient tree so this is just the treestomp.
Some people have never seen a really old and big tree and just assume they can't be bigger than the ones in their local forests.
But then again noone has ever seen such a big tree to know for sure this was one too.
I know there were really big tree hundreds of years ago but I just cannot imagine that there would be one that grows that big.
Who could clarify something like this and could present the truth?
I've seen hemp grow 4 meters in just a year and saw a cactus also 4meters high but that took over 400years. So there are sifferences in growtempo and if you give something enough time it might get that big..?
Truth is also the most believed theory in science for example so thruth can change as well.
Electrons were little balls circling around the core of the atom, now they are small waves doing the same. It changed with new discoveries but both are true to their respective point in time.

It IS true that I love my girlfriend but do I find two other sources that are not related to me and her that state the same? Probably but even if I am the only one that states that, it is true.

Very hard topic you have picked here:) I hope I added some value here with my statement.
Cheers!