# Hawking radiation **URL:** \ **Category:** Factual Questions\ **Created:** [August 16, 2007, 12:14am UTC](https://boards.straightdope.com/t/hawking-radiation/415759 "2007-08-16T00:14:30Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [August 16, 2007, 12:14am UTC](https://boards.straightdope.com/t/hawking-radiation/415759/1 "2007-08-16T00:14:30Z")
On another board I was giving a simplified explanation of what Hawking Radiation was. I can see the threadsteering towards the quantitative aspects, and want to be ready for that. Can the resident cosmologists here mathematically describe the relationship between a singularity’s mass and it’s event horizon’s surface area? Also, given the mass and surface area, how much energy and/or mass is radiated as hawking radiation. ---
**Author:** ![Beware\_of\_Doug](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)\ **Post date:** [August 16, 2007, 12:41am UTC](https://boards.straightdope.com/t/hawking-radiation/415759/2 "2007-08-16T00:41:56Z")
**RAAAAAADIATION! GIT YA FRESH HOT RADIATION HEAH! RAAA-DI-A…** …uh…never mind, I got nuthin’. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [August 16, 2007, 1:04am UTC](https://boards.straightdope.com/t/hawking-radiation/415759/3 "2007-08-16T01:04:38Z")
Gee, you’d think Wiki might have an article on black holes. [They do.](http://en.wikipedia.org/wiki/Black_hole) > [@](#): > > The Schwarzschild radius is given by > > r[sub]s[/sub] = 2Gm/c[sup]2[/sup] > > where G is the gravitational constant, m is the mass of the object, and c is the speed of light. For an object with the mass of the Earth, the Schwarzschild radius is a mere 9 millimeters — about the size of a marble. You can go to wiki’s [Hawking radiation](http://en.wikipedia.org/wiki/Hawking_radiation) page for your other formula. ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [August 16, 2007, 1:32am UTC](https://boards.straightdope.com/t/hawking-radiation/415759/4 "2007-08-16T01:32:34Z")
[QUOTE=Exapno Mapcase] Gee, you’d think Wiki might have an article on black holes. [They do.](http://en.wikipedia.org/wiki/Black_hole) You can go to wiki’s [Hawking radiation](http://en.wikipedia.org/wiki/Hawking_radiation) page for your other formula. [/QUOTE] The reason I was asking here was I needed to put the quantities in some human perspective: Mass=earth and Sr=9mm is exactly what I was looking for. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [August 16, 2007, 4:22am UTC](https://boards.straightdope.com/t/hawking-radiation/415759/5 "2007-08-16T04:22:07Z")
No sarcasm intended but I must be missing something. Why couldn’t you just do the math yourself once you had the formula? It’s extremely straightforward. Both G and the mass of the earth are one click away on Google. It’s a question I wonder about a lot of threads on physics here. I mean, I’m no whiz but I once got the basic formulas for relativistic light travel (they involve hyperbolic functions) and I set up a spreadsheet so that I could pop in any number and get any time, speed, or distance calculation. This is just multiplication. It really helps to do the math yourself. You get a much better feel for what the numbers mean by running several examples through the equations than you will by just reading what somebody else calculated. ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [August 16, 2007, 5:29pm UTC](https://boards.straightdope.com/t/hawking-radiation/415759/6 "2007-08-16T17:29:47Z")
I’ve always been kinda weak in the math department… :o