With growing technology, scientists have completed experiments that one only thought can happen in science fiction, such as keeping brains of pigs ‘alive’ outside their bodies for hours even after their death.

Neuroscientists from Yale School of Medicine performed a remarkable experiment last year, the details of which have recently been published in the journal Nature, which involved keeping brains of pigs alive for up to 36 hours after their death.

Scientist Nenad Sestan, along with his team, began the experiment by removing the brain from the severed heads of 32 pigs sourced from a local slaughterhouse, as per Futurism. The brains were then placed into specially designed chambers and were attached with catheters that let them pump a solution containing preservatives and other chemicals through the organs’ veins and arteries.

The team discovered that this system, which they dubbed as the BrainEx, restored some of the brain’s vital functions and helped maintain its internal structures. Eventually, the team kept some of the brains alive in this way for 36 hours.

This research has raised new questions about the nature of death, as per the team. “For most of human history, death was very simple,” neuroscientist Christof Koch, who wasn’t involved in the study, told Nature. “Now, we have to question what is irreversible.”

Moreover, Daily Mail reported that experts have warned that though this research proves to be a breakthrough, it will still long to proof that a human’s consciousness can be recovered after they die.