# The Unruh Effect

Every Time You Accelerate, You Create An Event Horizon

Part 1

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.

Categories: science

### 10 replies ›

1. The real reason a particle not moving at all would have a vertical world line boils down to gravity, yes? You are fun to read. You have to use your brain and think through what you’re saying. I like that. You’re a wonderful writer!

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• It isn’t really much of anything I have to think through. All these things come naturally to me. I am a scientist, not just a writer.

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• But of course you are! Your mind works completely on a different level than mine. I wonder how it would feel to have that brilliance? You have something special, you know?

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• You don’t have to wonder. Having this kind of brilliance makes sure in most of the cases that one doesn’t feel anything.

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• Well, then, I would probably never know. Unless something phenomenal were to happen that would change the chemistry of my mind.

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• It’s not just about the chemistry but also about the anatomy of one’s brain.

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2. I do wish I had been born with whatever it is that makes you smarter than you are. Some people are more intelligent and deserve the recognition. It’s a fact of life. Did you know that I used to believe that when I grew up, I would automatically know more? You can’t fix stupid, or can you? I say you can.

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• The first step towards fixing stupid is knowing that you are stupid and still have a lot more to learn.
Though you can’t really change the way your brain works. Everyone’s brain anatomy is different. You can’t overhaul the structure of a brain.
But one can always know and accept the fact that no matter how much one knows, it is and will always be less than 1% of the entire knowledge.

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