The aliens are silent because they're dead

[Witness]

To accelerate some mass to near-relativistic speed you'll also need energy, roughly as much as the mass itself (E = mc²). Then that again to brake. So the spaceship would need to start with enormous reserves of matter + antimatter, convert that with ~ 100 % efficiency, shield the crew (or computer) from the radiation, bleed the residual heat away, and a drive without propellant (the famed "photon drive"?).

No way.

[shemp]

Note: Within your own inertial frame of reference there is no increase in mass.

Then how come I keep gaining weight?

[Abdul Alhazred]

Note: Within your own inertial frame of reference there is no increase in mass.

Then how come I keep gaining weight?

Facing the wrong direction on the escalator again?

It's the Coriolis forces + something about being big boned.

[Rob Lister]

Well damn. Tell Amber she won't be able to quit early that night after all.

Seriously though, I just found a loophole in relativity--surely some plain Newtonian hurdle like micrometeors won't prove an insurmountable obstacle.

Thank god we invented the... whatever... that keeps those from damaging the ship. Maybe something mounted on the front that deflects them. A dish of some kind.

Nominally, according to lots of Sci-fi anyway, you'd want a huge electromagnetic field projecting out the front of the spaceship to "funnel in" all the Hydrogen atoms in the forward path of your ship and use that as fuel for your fusion generator.

There are between 0.1 to 1.0 atoms/cm2 in our local area (and ~1000 near the galactic core). It is a [not quite] trivial calculation to establish just how big/strong that field would have to be at any given speed to provide enough fuel to continue acceleration. https://hypertextbook.com/facts/2000/DaWeiCai.shtml

Maybe the pretend electromagnetic field that powers the pretend fusion generator on the pretend spaceship can also deflect the decidedly real spacedust.

[gnome]

Well there you go then!

Musk can start selling tickets.

[Abdul Alhazred]

Additional information:
Fermi famously asked: 'Where is everybody?' Probably dead, says renewed Drake equation
The Register

...

A team led by physicist Claudio Grimaldi of the Federal Polytechnical School of Lausanne in Switzerland – including Dr Drake himself – has suggested an update to the equation to take into account the time a civilisation might broadcast electromagnetic radiation that could be detected by Earthlings.

By considering the time between when a civilisation begins broadcasting to when that civilisation stops, the team is able to theorise a bubble expanding outwards at the speed of light.

The shell of the bubble is of a constant thickness, based on how long the civilisation endured.

For civilisations that blew themselves to bits after only a few hundred years, the thickness of this shell will be vanishingly small, making detection by Search for Extraterrestrial Intelligence (SETI) initiatives highly unlikely.

The paper suggests that civilisations that survive for 100,000 years or more will leave a shell thick enough to be spotted by SETI.

Anything less than that and the volume of the electromagnetic waves will be smaller than the galaxy, limiting detectability.

...