How to spot alien spacecraft?

[cronus]

This would only work for large craft approaching lightspeed and passing many stars, probably only applicable to craft in dense star clusters where actual physical journeys might be considered....a slight closing of stars along tracks that are a) linear b) self correcting indicating a course as well as a means of propulsion. Since very little would prevent star closings accelerating once underway those clusters once containing artifical routes would contain unusual lines of binary systems easily observable with current technology? Something else to consider?

[Clinton Huxley]

They proved you again, didn't they?

Getting near light speed would require prodigious amounts of energy, don't know if that could be spotted somehow.

[cronus]

They proved you again, didn't they?

Getting near light speed would require prodigious amounts of energy, don't know if that could be spotted somehow.

Energy isn't the issue for a sufficiently advanced technological civilization. At a point where you have a population increasingly self-maintained at a optimum level for a advanced-technical civilization whilst becoming ever more advanced it is no longer energy defining the game....if you can put a Dyson sphere around a inhabited star for home comforts you could arrange another for travel and stuff close by.

[Clinton Huxley]

Aye, and the use of that much energy may be detectable by us.

[cronus]

Aye, and the use of that much energy may be detectable by us.

A cloud of Dyson spheres might appear like dark matter since their stars would be masked at detectable frequencies if they were efficient?

[laklak]

Tachyon trails. That's how Picard tracked the cloaked Romulan ship.

[En_Route]

just look out your front window when the voicesyell you.

[Blind groper]

Having access to lots of energy does not give the ability to go near light speed. Energy is only one part of the equation. The other is reaction mass. To accelerate in a vacuum with no significant amounts of matter anywhere within light years requires the ejection of reaction mass at high velocity.

Not only do you need reaction mass to accelerate, but you also need heaps of it to decelerate again at the destination. This need to carry so much mass limits the maximum velocity a space craft can achieve. One article I read, written by NASA scientists, suggested 0.2c as the maximum theoretically attainable. The writers did not think much over 0.1c will ever be attained in practice.

[En_Route]

just look out your front window when the voices tell you.

[cronus]

just look out your front window when the voices tell you.

All of them or just yours?