Old thread: Last few posts:    On 5/11/2021 at 7:44 AM, Guard Dog said: (1) Voyager 1 detected 'Hum' in Deep Space - YouTube The best guess is gas of varying density. If interstellar space is full of gas that is curious and possible problematic. Velocity meeting resistance creates (micro)friction. Friction means loss of momentum. Sure we're talking about tiny changes but they would be both cumulative and exponential over time.    On 5/11