Found a fascinating video this morning!
I was reading about time-traveling and came across this party from 2009 that Hawking threw for time travellers. He threw a party expecting that time-travellers who were in the future at the time would hear about his party, travel to the past and show up to the party. However, no one came and Hawking waited for the whole time with the champagnes and balloons he prepared for his time traveller guests, and these images showing him waiting alone is kinda sad, it's so touching :D
The possible reasons why noone showed up are concluded in the video :
Time-travelling is not possible
It is only possible to move forwards in time
Time travel can only occur from the date, a time machine is first switched on
Time travel is possible, but no one figures out how to do it or they are too responsible to use it