Wouldn't GR prevent anything from ever falling in a black hole? | AskScience Blog

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Friday, August 26, 2016

Wouldn't GR prevent anything from ever falling in a black hole?

Wouldn't GR prevent anything from ever falling in a black hole?


Wouldn't GR prevent anything from ever falling in a black hole?

Posted: 25 Aug 2016 05:34 PM PDT

My lay understanding is that to an outside observer, an object falling into a black hole would appear to slow down due to general relativity such that it essentially appears to freeze in place as it nears the event horizon. So from our point of view, it would seem that nothing actually ever falls in (it would take infinite time) and thus information is not lost? What am I missing here?

submitted by /u/andrebis
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What form of numeric differentiation is this?

Posted: 25 Aug 2016 05:52 PM PDT

I needed to code up a quick check of a routine that returned the derivative of some function so I found myself doing (f(x+e)-f(x))/e as e got tiny. So far so good. Then a coworker said that in his experience (f(x+e)-f(x-e))/2e was more accurate for e > 0 because it was symmetric. I checked that in the limit e-->0 they returned the same derivative for simple functions. What form of numeric differentiation is this? Is it more accurate? Thanks!

submitted by /u/DrunkenPhysicist
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[Computer Science] Why do torrents slow down as you're reaching the very end?

Posted: 25 Aug 2016 04:16 PM PDT

What is the most effective form of sterilization of bacteria used in hospitals? Do hospitals in other countries use the same methods?

Posted: 25 Aug 2016 04:38 PM PDT

Hello Reddit, in the near future I plan on creating and designing my own experiment for my IB Biology IA. Currently, I am thinking on testing the effectiveness of different type of sterilization methods, presumably on tools in a hospital setting.

I've heard of different methods: Sanitizing Solutions, Boiling water/Steam, and even UV Lighting. But the real question I have is do other counties follow the same procedures and methods? Is there no "best" method of killing bacteria or do all kill with the same effectiveness? An answer would be very much appreciated as this will provide more depth and expand my experiment from just the United States, but the rest of the world. Thank you.

Also, if you have any tips or methods for measuring bacteria, that would also be appreciated.

submitted by /u/RelentlessRetort
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Why do we use Half-Life for elements and not Quarter-Life or any other fraction?

Posted: 25 Aug 2016 04:33 PM PDT

Why does fat distribution seem to change as people get older?

Posted: 25 Aug 2016 04:08 PM PDT

this is purely anecdotal as far as I know, but I know a ton of people who used to be chubby all around as teenagers and young adults, their body would put a lot of the fat in their thighs and in general spread pretty evenly around their body. As they get older it seems that they have totally fit looking legs and arms, but fat starts getting distributed straight to their gut (men and women alike.)

Is it known why this happens?

submitted by /u/timothybugjunior
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Silver or copper? Which is the better antimicrobial metal?

Posted: 25 Aug 2016 08:50 AM PDT

Hello!

I was recently researching about the antimicrobial properties of silver compared to copper, more precisely if theoretically Ag+ or Cu2+ (two active ions) would inhibit gram-negative bacteria to a greater extent under the same set of optimum conditions.

I wanted to find out which one would have a higher biocidal activity/ inhibition of a bacterium but found split opinions. Two sites for example suggest copper as the better substance. [1] [2]

Yet there is the much wider medical use of silver.

Secondly if the Cu or Ag would be in the compound for of AgNO3 and CuSO4 would the nitrate and sulphate group matter or would only the copper and silver cation inhibit?

submitted by /u/Dan0r
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Does extreme sleep deprivation cause hallucinations, and if yes, how/why?

Posted: 26 Aug 2016 05:10 AM PDT

Can there be current without voltage or voltage without current?

Posted: 26 Aug 2016 06:39 AM PDT

The following is an incorrect proof, but I cannot determine why. Help me with my physics, please! (I think the explanation lies with alternating current.)

Let us consider a circuit of a household located in the United States. This circuit begins at the electrical panel, connects to a receptacle, and then leads back to the panel. The receptacle has nothing plugged in, and so there is no load on the circuit. Therefore, no energy is being used, either; i.e., P=0. We also know that V=120, because this is an American household. Now, by definition of power, P=IV, which implies P=120I by our assumption about voltage. Furthermore, P=0 implies 0=120I, or that I=0. However, using Ohm's law, V=IR, we see that 120=0*R implying that 120=0, which is a contradiction. ///

submitted by /u/saint_sipes
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If a new country was formed and wanted to make it's own fiat currency, and the international community recognized it, how would the value be determined?

Posted: 25 Aug 2016 02:25 PM PDT

Is there an equivalent to a nucleation site in phase transitions other than liquid to solid?

Posted: 25 Aug 2016 11:45 PM PDT

How does the Blockchain work?

Posted: 26 Aug 2016 04:58 AM PDT

How does a Blockchain work mathematically. What is a Block and what do I need to calculate a Hash?

submitted by /u/traendy
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Why is the atmosphere of Earth primarily Nitrogen and Oxygen while our nearest neighbors, Venus and Mars, both have atmospheres of mainly CO2?

Posted: 25 Aug 2016 02:52 PM PDT

What would happen if the speed of light suddenly increased by 1%?

Posted: 25 Aug 2016 10:37 AM PDT

Obviously, I assume it would experimentally be quite easy to find out that the universal speed limit of the universe is now 303,000km/s, but what effects would be visible to the human eye, if any?

What if we up that number to say 350,000km/s?

submitted by /u/Zaldebaran
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If a collision in the large hadron collider created dark matter, would it detect it?

Posted: 25 Aug 2016 03:21 PM PDT

As fat as i've understood it, dark matter does not react with regular matter, so could it be detected in high caliber experiments like the Large Hadron Collider. If not, how would you detect it on earth?

submitted by /u/Penetrator_Gator
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How does encryption actually work?

Posted: 25 Aug 2016 11:02 AM PDT

I understand that 2 primes are easy to multiply together, but hard to find the combination of primes that makes a number, making it an almost irreversible calculation (except looping through every possible combination), however I have never come across an explanation as to how this is actually used to encrypt something - what do these two (or more?) numbers have to do with what I want to encrypt?

For example, if I want to encrypt the character "b", ASCII 98, how does this work? Would it be 98 multiplied by a random prime?

Also, is this the same as "hashing"? I understand the salt, but not the process of the original hashing... (Descriptions I have been given of hashing go along the lines of "calculations that are only 'one way'")

Thanks, Matthew

submitted by /u/-TheMightyMat-
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Why are new elements made in more or less numerical order?

Posted: 25 Aug 2016 02:31 PM PDT

The artificial elements created in particle accelerators, most recently #118 i believe, have been created in more or less numerical order. As far as i know, they are created by smashing nuclei of two different lighter elements, who's atomic numbers add up to the number of the desired element. So why don't physicists 'jump ahead', for example to the theorized islands of stability?

submitted by /u/baldman1
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what are the p-adic properties of the partition function and how does the proof work?

Posted: 25 Aug 2016 11:58 AM PDT

I'm a high school student doing advanced maths, and came across an old news story about Ken Ono's advancement of partition theory. i understood the basic concept, but i couldn't understand the paper link to paper: http://aimath.org/news/partition/folsom-kent-ono.pdf

submitted by /u/WJTDroid
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Why do electric fields and current density tend to concentrate at areas of high curvature and in narrow channels?

Posted: 25 Aug 2016 08:49 AM PDT

I am working on a Comsol model for my research, and I've noticed that I have some pretty non-uniform fields, and I can't seem to explain why I have such high gradients. Any help would be appreciated!

submitted by /u/bme_phd_hste
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How can different oil products be transported through the same pipeline without mixing?

Posted: 25 Aug 2016 04:36 AM PDT

I've listen to the planet money episodes about oil and they mentioned that oil and oil products can be transported via pipelines without mixing.

How is that possible? Is there no mixing at all or only very little that it can be ignored?

submitted by /u/H4kor
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