Oumuamua is leaving us at high speed.

Humans try to follow it with the VLT, and they report that the thing...
is accelerating.

Accelerating?

When I first saw the drawings I thought:

Gosh! This is a spaceship. It really looks like one.

Other humans tried to listen if it emits any comprehensible signals.
They got nothing in radio frequencies, the only ones we know about.

Accelerating?

But how?

Astronomers put forward the theory of some kind of "outgassing" from its
encounter with the sun. Problem is, and they are honest enough to say
it, is that no outgassing is seen.

The surface of this thing was bombarded by the sun, no problem. But
since it is tumbling, there is no preferencial side that gets more
illuminated than any any other, and at most, that would produce a dust
grain cloud around the object. But that would not furnish any THRUST!

Acceleration needs a force vector. The outgassing must be concentrated
in one direction to make the desired effect.

This thing is moving, i.e. it can change its velocity vector. This a
clear sign of life.

"Spaceship" is making this thing human-like, and this tumbling object is
surely not. But we dreamed of it in our novels and stories.

Why?

Bceause of the evidence: if we aren't the only ones around, there are
beings more advanced than us that can travel around.

Is this velocity vector change just the result of random fluctuations of
the debris cloud?

And why the hypothetical invisible coarse grains that get off the
surface of this object (if they exist, as astronomers propose) should
have a special direction?

The object is tumbling. At least it was tumbling when it passed nearby.

And it is quite massive too. Km wide.

Accelerating this thing?

And accelerating so fast that we can detect it?

If we are all serious and agree that spaceships do not exist, we will
never see one when it passes by.

A pity for us. Oumuamua is leaving us at great speed. Changing its
course for new endeavours.

jacob

[[Mod. note -- Yes, many of us have read "Rendezvous with Rama".

But it seems to me that for Oumuamua the "comet-like outgassing"
hypothesis is strongly favored by Occam's razor: we know that other
objects (comets) outgas in this way (many comets are observed to have
non-gravitational accelerations of this type), and if Oumuamua has
spent little time near a star it's quite plausible that its surface
still has plenty of volatiles (e.g., frozen water and/or methane)
which would vaporize (outgas) when heated by a close solar passage.

And, unlike Rama, Oumuamua's spin (tumbling) period seems to be a
lot longer than 4 minutes.
-- jt]]