Question

Black holes!

Answer 1

Yesterday i read the newspaper, and i came across something about black holes . Well , i seriously don't know very much about them. Can anybody help here understanding these?

Answer 2

You'd find a lot more information on google. I can only describe them in a little detail.

Answer 3

Pls can you help a little bit in the basics?

Answer 4

google it

Answer 5

This article sums it up pretty well:
http://www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-is-a-black-hole-k4.html

Answer 6

kai...be cool here ;)

Answer 7

It's so damn confusing everywhere. I want a simple and sweet explanation for that.

Answer 8

Were you reading about gravitational waves yesterday ?

Answer 9

The language is even more confusing where i am looking right now.

Answer 10

Yes..

Answer 11

Do you also look at stars and wonder what happens when they run out of gas ?

Answer 12

Lol. I do the first half of the statement you made.

Answer 13

You could skip to page 32 of the book (page 21 of the PDF) here http://amarketplaceofideas.com/wp-content/uploads/2014/08/P%2520A%2520M%2520Dirac%2520-%2520General%2520Theory%2520Of%2520Relativity1.pdf

chapter 19 there and skim the math you don't understand and sorta see what you can pick up until you get to the end of the chapter where he basically summarizes it.

PROBABLY not gonna help so don't like stress out about it lol. But like this is how black holes were originally mathemtically predicted and got their name basically, from this specific solution of the Einstein equations I believe.

Answer 14

First of all, do you know how a star produces all of its energy ? For example, consider sun. Roughly speaking, sun has lots of small atoms which fuse together to produce sonewhat stable bigger atoms. This process is called nuclear fusion and it releases energy. What do you think happens when the process ends ? That is, when the sun uses up all the small atoms ?

Answer 15

When the sun has used up all of its small atoms , it should have released a lot of energy and so it should now contract .

Answer 16

Exactly! When it contracts and collapses into a small region, what happens to its density ?

Answer 17

Yep, gravitational pressure causes contraction (the energy created by fusion prevents this contraction, but when fusion slows or ceases...)

Gravitational pressure is also what causes fusion in the first place.

Answer 18

Density must increase!

Answer 19

And if it's a star with a lot of mass...

Answer 20

Well! If a thing contracts into a small space then it's volume is definitely decreasing greatly so can't we say that it's density is influenced a lot in the increasing sense.

Answer 21

yes, you have the right idea.
If a star was sufficiently massive, it would turn into a black hole after it contracts. But our sun is not so massive to become a blackhole. This brings us to your original question : what is a black hole ?

Answer 22

Exactly ! The same thing i read just now as to what sort of stars make up a black hole.

Answer 23

Awesome! I hope you could google rest of these fascinating phenomena. Do post here your findings. Have fun !

Answer 24

Oh! Absolutely ! I am doing that process .

Answer 25

http://jiaps.org/assets/3-FormationofNeutronStar2.jpg

Answer 26

http://www.emc2-explained.info/Emc2/Fusion.htm#.V2Tr6WnhXqD

Answer 27

This is quite a fascinating thing to do !

Answer 28

Of course it is. Can you imagine how big our sun gets when it goes through the phase of a red giant ?

Answer 29

A huge size it must have attained by the time it gets to its red giant stage.

Answer 30

None of us are physicist specializing in the field of your inquiry. Please refer to scholarly articles instead or for starters, use youtube videos from World Science Foundation and similar events.

Answer 31

Very huge indeed ! If you were living to see it, and if you had evolved to not get harmed by radiation, you can touch the sun by rising your hand from a tall building.

(Just exaggerating)

Answer 32

@nincompoop you don't need to have a degree in a particular subject to clear a small question of a fellow student

Answer 33

Will anyone be able to survive if sun acquired that phase ?

Answer 34

:) maybe
But even theoretical physicist took time to unravel its mysteries.

Answer 35

That's so cool! Touching sun from my finger.

Answer 36

@nincompoop some of us have degrees in physics, though.

Answer 37

https://www.youtube.com/watch?v=NMxo98Y-KoE

http://www.hawking.org.uk/into-a-black-hole.html
http://www.briangreene.org/papers/BlackHoleCondensationandUnificationofString.pdf.zip
https://www.youtube.com/watch?v=7DBKVL9Wqkw
https://www.youtube.com/watch?v=LCgU7KZQCN8
https://www.youtube.com/watch?v=BWn29kYjOZQ

Answer 38

I am a fan of black holes too and I can regurgitate many of the stuff I've read and watched. This, however, does not indicate knowledge on the matter.

Answer 39

@samigupta8 no, humans could not survive once the sun reaches the red giant stage.

Answer 40

Yes! Thanks

Answer 41

I wish that i were alive till that time and have that experience provided ganesh sir's thing could be applicable for me.

Answer 42

But it's not likely humans would still exist at that time, or at the very least, not in the current form of "human".

Answer 43

This reminds me of a cute little story from Hindu scriptures. Hanuman, when he was kid, looks at the red setting sun and assumes that its a delicious apple. He goes after it and you can guess now why his were like this ;)

http://www.thehindu.com/multimedia/dynamic/00618/2007123050600201_618817g.jpg

Answer 44

*lips

Answer 45

This is a good one !

Answer 46

If i throw my feet into black hole, i would enter a new world. Is it really true?

Answer 47

BRB .

Answer 48

Not likely, but the difference in gravitational pull between your head and feet might stretch your brain to the point of making you think you entered a new world.

Answer 49

Illusion!

Answer 50

theres a term for that spaghettification

Answer 51

Yep. If you were really, really, really tall, you'd feel a similar effect on Earth.

Answer 52

Nin , the second link you provided here is awesome.

Answer 53

Can we discuss about it ?

Answer 54

We may start by pickng on a specific question

Answer 55

Okay ! Cool. So who is the first one to ask here?

Answer 56

Have you watched the movie interstellar ?

Answer 57

I don't know if i had get knowledge on it but i can say i have tried to grasp it for a bit.

Answer 58

Nope.

Answer 59

While youre pondering about blackholes and stuff, try to watch it. It has warmholes, blackholes and 4-D tesseracts etc and a lots of drama. But you're gona like it!

Answer 60

Sure! I will seek forward to watch it.

Answer 61

So what shall i do now? You were asking questions . I guess.

Answer 62

So you want me ask a question hmm let me think a bit

Answer 63

Yes.

Answer 64

You've said earlier that you wish to put your feet on a blackhole. Do you know where is our nearest blackhole and how long it takes to reach it ? (w/o considering relativity)

Answer 65

Nearest blackhole! I don't know .
Is it Saggitarius A?

Answer 66

1600 light yrs away is a black hole.

Answer 67

Yes. You must also have known that you can't see a blackhole because it sucks light too. So how did we discover its peesense in the first place ?

Answer 68

Telescopes (scientists can do anything to have a look of them)

Answer 69

What good is a telescope if light cannot be reflected from a blackhole ?

Answer 70

I read that some stars which are near to the black hole make it possible to see it.

Answer 71

Sorry, telescopes won't make it .

Answer 72

Also can you imagine how big is 1600 light yrs ? How much time does it take to travel that distance ?

Answer 73

Very large distance it is.

Answer 74

1 light year is of order of 10^12 km

Answer 75

Yeah it all started when scientists saw a bright star circling a seemingly empty space.

What's needed to make things go in a circle ?

Answer 76

Pull.

Answer 77

A gravitational pull that can make anything go in a circular fashion

Answer 78

Its insanely huge distance ! So your dream of landing on a blackhole never gona materialize. Give it up!

Answer 79

Anybody has tried to go over there?

Answer 80

Suppose I tell you the orbital radius and mass of that bright star. Can you calculate the mass of the unknown thing it is circling around ?

Answer 81

Yeah...

Answer 82

@samigupta8 our furthest probe, voyager 1, is only just outside the solar system. We have no plans to attempt to visit a black hole.

@ganeshie8 the mass of the star orbiting the black hole isn't needed :P

Answer 83

Centripetal force is provided by gravitational pull of that unknown thing.

Answer 84

Oh right, right. If we think of that bright star as a satellite, mass gets cancelled away during the derivation. Ty for correcting :)

Answer 85

@agent0smith plans are not made yet to visit that hole. Why?

Answer 86

You see that scientists can dig into the properties of that unknown thing using indirect methods like these

Answer 87

Like what?

Answer 88

@samigupta8 because even travelling at the speed of light, it's a 3,200 year round trip.

Answer 89

Oh my my ! Who is so brave to spend his 9 years spinning around .?

Answer 90

There's a particular place also. I am not able to memorise its name at the moment where people go and never return.

Answer 91

Mysterious place indeed.

Answer 92

9 years and our intervals of lives are negligibly small in comparison to the astronomical phenomena

Answer 93

Looks youre thinking about Bermuda triangle

Answer 94

You got it right!

Answer 95

Are you planning to spend 9 years of your life for that?

Answer 96

Hmm idk. But how did you get the number 9 ?

Answer 97

Lol.. Approximated it