Hello, A very interesting news came out these days about a group of astrophysicists found a way to make a path of direction of many known galaxies in the area. By area I mean a large cube of 500 million light years wide called Laniakea which has nothing to do with Ikea. They used intense calculations, (Hélène Courtois), http://www.francetvinfo.fr/sciences/espace/qu-est-ce-que-laniakea-le-superco... The result is astonishing and the word is weak, it is mind blowing in my opinion. See the short film (in french). So according to those calculations, one thing we already knew is that our own galaxy is travelling at a speed of 630 km per second, this is impressive if we consider the mass of the galaxy, it takes 476 years to travel 1 light year and since the beginning of the known birth of earth, we travelled about 10 million light years. BUT : there is a simple question : how can this be possible if we consider the pure energy to accelerate such an astronomic mass (the weight of the galaxy), and in more general terms : how can such a mass can acquire any speed at all ?? Can anyone has an explanation for this ? best regards, Simon Plouffe