# How much would a nearby black hole help our physics? **URL:** \ **Category:** Factual Questions\ **Created:** [March 23, 2015, 5:06pm UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797 "2015-03-23T17:06:24Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![get\_lives](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@get\_lives](https://boards.straightdope.com/u/get_lives)\ **Post date:** [March 23, 2015, 5:06pm UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797/1 "2015-03-23T17:06:24Z")
Let’s say we had a nearby very small black hole, just a couple of light years away, that was in a direction perpendicular to the ecliptic. How much easier would it be to come up with a Unified Field theory than it is now? Given everything else being the same. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [March 23, 2015, 5:40pm UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797/2 "2015-03-23T17:40:20Z")
My gut reaction: not at all. There are two scenarios I can think of in which it would make a difference: [ul][li]Gravitational waves behave substantially differently than we expect them to, due to quantum-gravitational effects; and we observe gravitational waves due to objects falling in to the black hole. This is pretty unlikely, though, given the [indirect evidence](https://en.wikipedia.org/wiki/PSR_B1913+16) we have for gravitational waves; the Universe would have to be conspiring against us pretty intensely for this to be the case.[/li][\*] The black hole is _really_ small, so that it’s putting out enough [Hawking radiation](https://en.wikipedia.org/wiki/Hawking_radiation) that we could study it and notice any differences from the classical predictions. The problem with this is that larger black holes actually emit _less_ Hawking radiation, so we’d need a relatively tiny black hole for this to work. If I’ve done my sums correctly, a black hole with a mass of about 10[sup]8[/sup] kg, or around the mass of a large sea-going ship, would be visible from Earth (bolometric magnitude of +25); but as far as we know, black holes that small can’t form naturally.[/ul]ETA: I should say that the influence of the black hole on objects in our solar system is just going to be like that of a star of the same mass at the same distance; which is to say, not much. We would need something, like gravitational waves or Hawking radiation, that originate near the black hole and travelled to us. ---
**Author:** ![get\_lives](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@get\_lives](https://boards.straightdope.com/u/get_lives)\ **Post date:** [March 23, 2015, 8:57pm UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797/3 "2015-03-23T20:57:55Z")
See, I had this whole theory cooked up where a civilization could advance much faster after a certain point because of such a thing. Damn. 🙂 ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 24, 2015, 7:51am UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797/4 "2015-03-24T07:51:18Z")
Are we going to be happy observers with an an energetic x-ray source in our near neighbourhood? ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [March 24, 2015, 1:57pm UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797/5 "2015-03-24T13:57:18Z")
> [@MikeS](#): > > The black hole is _really_ small, so that it’s putting out enough [Hawking radiation](https://en.wikipedia.org/wiki/Hawking_radiation) that we could study it and notice any differences from the classical predictions. The problem with this is that larger black holes actually emit _less_ Hawking radiation, so we’d need a relatively tiny black hole for this to work. If I’ve done my sums correctly, a black hole with a mass of about 10[sup]8[/sup] kg, or around the mass of a large sea-going ship, would be visible from Earth (bolometric magnitude of +25); but as far as we know, black holes that small can’t form naturally. Not to mention that it would only last like 2.6 years (if I did that right). ---
**Author:** ![get\_lives](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@get\_lives](https://boards.straightdope.com/u/get_lives)\ **Post date:** [March 24, 2015, 3:30pm UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797/6 "2015-03-24T15:30:06Z")
> [@MrDibble](#): > > Are we going to be happy observers with an an energetic x-ray source in our near neighbourhood? See, there’s the rub. Although I imagine life in a place like that would evolve better DNA repair than we have. ---
**Author:** ![Nancarrow](https://avatars.discourse-cdn.com/v4/letter/n/c37758/32.png) [@Nancarrow](https://boards.straightdope.com/u/Nancarrow)\ **Post date:** [March 24, 2015, 3:36pm UTC](https://boards.straightdope.com/t/how-much-would-a-nearby-black-hole-help-our-physics/715797/7 "2015-03-24T15:36:41Z")
> [@MikeS](#): > > … but as far as we know, black holes that small can’t form naturally. Which would make it an even MORE useful tool for helping our physics, no? 😉