Giant vortices, black discs surrounded by spectacular light effects - these are the most popular representations of black holes, regions of space where there’s such a strong gravitational field that nothing can escape from it, not even light. However, such representations are inaccurate, even fantastical.
After briefly illustrating what black holes are and touching upon the historical debate that led scientists to assume they exist, astrophysicist Alain Riazuelo leads us into an incredible virtual journey, where we travel towards the heart of a black hole.
The animation is the result of numerical simulations based of the equations of general relativity. Let’s suppose we reach 99% of the speed of light. This is close to the maximum speed we can reach according to the laws of physics. As speed increases, the celestial bodies located in the direction we are moving to seem to shrink. This physical phenomenon is called “the aberration of light”. Also, the celestial sphere gets more and more distorted; the sky becomes darker and darker behind us, but increasingly brighter in the direction we are travelling to.
The colour of the stars change. Their light becomes bluer when the light source is approaching, and redder when it recedes. It’s the Doppler effect, the same phenomenon that causes the sound pitch of an ambulance siren to change based on whether the ambulance is approaching or receding from us.
We will also experience “gravitational lenses” - deflected light trajectories caused by the gravitational field of the black hole, which is also responsible for ghost images. Finally, we will get to the heart of the black hole itself, from which we will never be able to come back. An equally pedagogical and aesthetical journey.