The three brothers

Question

Here is a tough riddle:

The three brothers live in a house
They look truly different
But if you want to see the difference,
Is each one like the other two

The first one is not here, he is just coming home
The second one is also not here, he already went out
Only the third is here, the smallest of the three
Because without him, there wouldn't be the other two

And yet, there's the third one in question
Because he is the first, who turns the second to the third
But if you want to look at him,
Then you will only see one of the other brothers

Now tell me: Are the three maybe one?
Or are they two? Or none at all?
And now, can you tell me their names?
Then you will see three powerful rulers who rule a great empire

No king, no president, can own their kingdom
Because the kingdom they rule, they are that themselves
If you take a look at their kingdom, then maybe you can only see stuff
But if you look closer, you can see $\color{red}{\mathsf{y}\mathfrak{ou}}$

Can you solve it?

Answer 1

I think the three brothers are

past, present, and future.

I think I wrote a riddle a while ago with exactly the same theme/solution (but maybe I was just thinking of this one).

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The three brothers live in a house
They look truly different
But if you want see the difference,
Is each one like the other two

I guess the house is time. Of course past, present, and future all look very different from our point of view sitting at a single moment in time, but objectively they're all part of history.

The first one is not here, he is just coming home
The second one is also not here, he already went out
Only the third is here, the smallest of the three
Because without him, there wouldn't be the other two

The first one is the future, the second one is the past, and the third one is present, the smallest (existing only at a single moment) and allowing the existence of the others through the flow of time.

And yet, there's the third one in question
Because he is the first, who turns the second to the third
But if you want to look at him,
Then you will only see on of the other brothers

The present turns the future to the past, but it's impossible to pin down because it exists only at a single infinitesimal moment - look at the moment and it's either gone or still coming.

Now tell me: Are the three maybe one?
Or are they two? Or none at all?
And now, can you tell me their names?
Then you will see three powerful rulers who rule a great empire

Time is a complicated beast, philosophically. Maybe their empire is history.

No king, no president, can own there kingdom
Because the kingdom they rule, they are that themselves
If you take a look at there kingdom, then maybe you can only see stuff
But if you look closer, you can see you

Nobody is powerful enough to own history - the past, present, and future comprise history. But we are all part of it, if you look close enough.

Answer 2

One more answer:

Three hands of clock. hour hand is the third, the minute hand is the second, the second hand is the first

The three brothers live in a house
They look truly different
But if you want see the difference,
Is each one like the other two

The house is the clock or time. Same as @Rand formulated, they look different if you take a closer look

The first one is not here, he is just coming home
The second one is also not here, he already went out
Only the third is here, the smallest of the three
Because without him, there wouldn't be the other two

The first one is coming to 12. The second one is going to it, the third one is exactly there.
When the hour was not there, there would also not be the minute or second

And yet, there's the third one in question
Because he is the first, who turns the second to the third
But if you want to look at him,
Then you will only see on of the other brothers

The hour turns the second-hand go after the minute-hand! - To the second place!

Now tell me: Are the three maybe one?
Or are they two? Or none at all?
And now, can you tell me their names?
Then you will see three powerful rulers who rule a great empire

The empire is the clock or time

No king, no president, can own there kingdom
Because the kingdom they rule, they are that themselves
If you take a look at there kingdom, then maybe you can only see stuff
But if you look closer, you can see you

Nobody can rule history. You may only see numbers, but we are also part of it.