Every Time You Accelerate, You Create An Event Horizon
Every time you accelerate, put your foot on the gas, quicken your step, get out of your chair, etc. you generate an “Event Horizon” behind you.
The more you accelerate away from it, the closer it gets. Though it can never catch up to you, but the Unruh Radiation it generates sure can.
Around the same time when Stephen Hawking was demonstrating the existence of the Black Hole radiation, 3 other researchers – Stephen Fulling (1973), Paul Davies (1975) and William G. Unruh (1976), were all looking at an effect that now seems eerily similar.
They were independently studying how the nature of Quantum Fields appears to change depending on whether or not the observe is accelerating. They found that the simple act of acceleration cuts off your casual access to the region of the Universe.
The presence of horizon distorts the quantum vaccum in a way that can create particles. This is the Unruh Effect. It tells us that accelerating observers find themselves in a warm bath of particles.
To understand this, we don’t need General Relativity or its conflict with Quantum Mechanics.
We just need a little Special Relativity and Space-Time diagrams.
A Space-Time diagram has 2 axis, time and space with time on the vertical axis. We can show object’s path through space and time using world lines on the diagram.
For an object with a constant velocity, an inertial object, these world lines are just straight line, and slope gives their velocity.
A particle not moving at all has a vertical world line.
Einstein taught us that an object without rest mass, like a photon, can only travel at speed of light; nothing less.
On a Space-Time diagram, this would be a line making 45o from the vertical axis.
Objects with rest mass can never reach speed of light, so their world line are less than 45o from vertical.