For long, scientists have been trying to understand when does an object exactly enters a black hole and what happens to it after that. However, what is present inside the black hole remains unknown to date.
The universe is supposedly expanding and the galaxies are drifting apart. Also, the regions of the space are getting stretched. However, there is no centre from where the universe is expanding and no outer edge beyond which it won't expand, so it is not known what is it stretching into.
The universe is estimated to have been created approximately 13.77 billion years ago. At that time, it was inconceivably hot and very small, nearly the size of a pear. However, what remains unknown is what happened in the first 10 seconds after the universe was formed.
Nearly 68 per cent of the entire universe is dark energy and around 27 per cent of it is dark matter. Dark energy also affects the expansion of the universe. But what exactly is dark energy remains a mystery.
Scientists have been making all possible efforts to find any traces of life beyond Earth and have also studied various exoplanets to understand if any other place has a chance of life. However, the existence of extra-terrestrial life has remained a mystery so far.