Blog Post 3: Generating Energy

Welcome back everyone,

There are many theorized methods to collect energy from black holes. Today I am just going to be talking about a few of the ones I feel have significant potential. Of course, this can change due to advancements in technology or advancements in theoretical physics.

The first method we will discuss was proposed by 1983 by George Unruh and Robert Wald. It’s called the box or the bucket method and it requires lowering an energy collection device (the box/bucket) into the event horizon of the black hole. The box will be attached to a string, which will be used to pull the box back up from the event horizon. A great analogy is like pulling water up from a well using a bucket. The water can be the hawking radiation, while the bucket is the energy collection device and the rope is well, the rope.

At first glance, this method looks great. However, as the box get closer to the center, cracks start appearing in the theory. In principle more energy can be extracted per second from a single black hole than is radiated from all the ordinary stars in the observable universe. However, some problems with this theory are:

• Rope stretching due to massive gravity

• Rope disintegrating

• Rope being able to support very little mass other than its own

These problems only occur when you are closer to the event horizon where the most amount of hawking radiation lies. However, the further away you move from the event horizon, the less hawking radiation there is available for you to collect.

A second theory was proposed in 1994 by Albion Lawrence and Emil Martinec. They tried to simplify the process by proposing the “wick” theory. The idea was to use strings and let Hawking radiation run up them like wick on an oil lamp. A good analogy is like current

running up a wire. Although, this process is much slower and less efficient I believe that if humans develop artificial black holes (something I will talk about more in my latter blog posts), this process would include much lower maintenance and mankind could have entire black hole farms operating in space.

Another theory which is much more ambitious is the “spherical” theory, also known as the “radiation” method, which aims to ensure near 100% Hawking radiation absorption. The way this method works is to completely envelop the black hole in a sphere. The sphere will actually be hundreds of solar panel like structures will be absorbing the hawking radiation emitted by the black hole. Then the solar panel like structures will transform the energy into usable form. From there the energy will be transported to wherever humans need them. This sphere will also have an input tube, from where materials will be “fed” into the black hole. Because after all, the black hole needs to have mass, to convert to energy.

These are just three of the tens of theories out there regarding energy generation from black holes. The radiation method looks the most promising, as it is heavily based on current technologies and also, it will be the most practical. We constructed a model of the wick model to demonstrate to the general public a potential way we will extract energy in the future.

The possibilities are endless.

Dr. Chinmay Patel (PhD in Astrophysics)

Professor at Stanford University

Links:

Ball, Philip (Dec 3, 2013). Could we harness energy from black holes? Retrieved From: <http://www.bbc.com/future/story/20131203-could-black-holes-provide-energy>

Anderson, Ryan (November 19, 2009). Black Hole Drive could power future Starships. Retrieved From: <http://www.universetoday.com/45571/black-hole-drive-could-power-future-starships/>

Jones, Zimmerman, Andrew (2010). What is Hawking Radiation? Retrieved From: < http://physics.about.com/od/astronomy/f/hawkrad.htm>

123HelpMe.com. "Black Holes: The Power Source for Future Space Travel?" Retrieved From: <http://www.123helpme.com/view.asp?id=43865>

Whiting, Jim. (2011). Mysteries of the universe: Black Holes. New York, USA. Publisher: Creative Education. Book.

DeGrasse, Tyson. (2007). Galactic Engines. Death by Black Hole and Other Cosmic Quandaries. (pg. 268-274). New York, USA. Publisher: Norton. Book.

Begelman, Mitchell. (2010). Gravity Triumphant. Gravity’s Fatal Attraction: Black Holes in the Universe. (pg. 1-22). New York, USA. Publisher: Cambridge University Press. Book.

#Chinmay