A Question About Globular Clusters

[Simple Peasant]

To what extend could one make use of gravitational assist for increasing spacecraft speed if one lived in a large, tight globular cluster? Crossing from one side of the cluster to the other a spacecraft could make use of numerous stars for assist.

This may well have happened quite naturally numerous times with planetisimals and planets.

What happens to the speed or nature of a photon when it passes close to a black hole but not so close that it gets captured?

Simple Peasant

[Qev]

To what extend could one make use of gravitational assist for increasing spacecraft speed if one lived in a large, tight globular cluster? Crossing from one side of the cluster to the other a spacecraft could make use of numerous stars for assist.

No reason why not, though one's course would have to be carefully plotted to take advantage of the various stars' orbital motions. Would take quite a while I imagine.

This may well have happened quite naturally numerous times with planetisimals and planets.

Most certainly. Complex systems like this often eject unlucky bodies through gravitational interactions.

What happens to the speed or nature of a photon when it passes close to a black hole but not so close that it gets captured?

Well, its path will be bent by the distorted spacetime around the black hole, similar to passing through a lens (but not identical). Falling towards the black hole, light is blueshifted, climbing away from a black hole, light is redshifted. I imagine these effects cancel out for light not originating near the 'surface' of the black hole, however.

Simple Peasant[/quote]