# Black Holes May Have High-Energy 'Firewalls' That Mark the End of Space

Black holes are one of the most elusive phenomena in our universe, and the insides of them might be even more exotic than we thought. According to a recent theory, black holes may contain "firewalls" around their event horizons, or borders made of high-energy particles that disintegrate any matter that passes through them and may even mark the end of space.

Black holes as predicted by Einstein's theory of relativity present a conundrum to theoretical physicists, as quantum mechanics seems to break down once the event horizon enters the equation. The event horizon is essentially the "point of no return," or the point at which the gravitational pull becomes so great that there's no chance of an object escaping. It will inevitably continue to fall into the hole until it reaches the singularity, or the point at which the spacetime curvature becomes infinite.

According to the prevailing theory of black holes derived from general relativity, there is no discernible border to the event horizon, but rather an observer would just travel through smooth continuous space without noticing any change. But according to the firewall theory, this assumption is erroneous, and actually there are high-energy borders that would destroy any object immediately, before it had a chance to pass through the event horizon.

Theoretical physicist Joseph Polchinski of UC Santa Barbara, who was part of the research team that conceived of firewalls, explained in the April issue of Scientific American,

According to Polchinski, this theory is consistent with quantum mechanics and brings us one step closer to unifying it with general relativity. In this video from Scientific American, he explains the concept in more detail, as well as the theory of black holes in general and the implications for both quantum mechanics and general relativity:

If the firewall theory is true, then it would not only assist physicists in their quest for a "theory of everything," but would help us understand the nature of our universe as a whole. As Polchinski states in the video,

Black holes as predicted by Einstein's theory of relativity present a conundrum to theoretical physicists, as quantum mechanics seems to break down once the event horizon enters the equation. The event horizon is essentially the "point of no return," or the point at which the gravitational pull becomes so great that there's no chance of an object escaping. It will inevitably continue to fall into the hole until it reaches the singularity, or the point at which the spacetime curvature becomes infinite.

According to the prevailing theory of black holes derived from general relativity, there is no discernible border to the event horizon, but rather an observer would just travel through smooth continuous space without noticing any change. But according to the firewall theory, this assumption is erroneous, and actually there are high-energy borders that would destroy any object immediately, before it had a chance to pass through the event horizon.

Theoretical physicist Joseph Polchinski of UC Santa Barbara, who was part of the research team that conceived of firewalls, explained in the April issue of Scientific American,

**"It now seems that our astronaut would have an experience very different from Albert Einstein's prediction. Rather than falling seamlessly into the interior, the astronaut would encounter a 'firewall' of high-energy particles at the horizon that would be instantly lethal. The wall might even mark the end of space."**According to Polchinski, this theory is consistent with quantum mechanics and brings us one step closer to unifying it with general relativity. In this video from Scientific American, he explains the concept in more detail, as well as the theory of black holes in general and the implications for both quantum mechanics and general relativity:

If the firewall theory is true, then it would not only assist physicists in their quest for a "theory of everything," but would help us understand the nature of our universe as a whole. As Polchinski states in the video,

**"In some ways the inside of a black hole is like our expanding universe. The geometry of space and time is changing, and there's a singularity. So... they're a step towards understanding our own universe."**