# kind of a galaxy question I think ???

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#### unseen

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Take a picture of NGC 3310 if we were on the other side of that galaxy would the picture look the same or would we not see it all?&nbsp;&nbsp;&nbsp; I guess what im asking is (who knows&nbsp;&nbsp; haha)&nbsp; if space time is curved when we view a galaxy are we only seeing galaxies that face us or do we see all galaxies.&nbsp;&nbsp; My narrow minded thinking would tell me that all galaxies are kinda cone shaped and if we were dirrectly in the otehr side of the galaxy we would not even see it because it is all within the cone so all we would see is empty space?&nbsp;&nbsp;&nbsp; Anyway just thought i would askk thx.&nbsp;&nbsp; &nbsp; <div class="Discussion_UserSignature"> </div>

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#### weeman

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Take a picture of NGC 3310 if we were on the other side of that galaxy would the picture look the same or would we not see it all?&nbsp;&nbsp;&nbsp; I guess what im asking is (who knows&nbsp;&nbsp; haha)&nbsp; if space time is curved when we view a galaxy are we only seeing galaxies that face us or do we see all galaxies.&nbsp;&nbsp; My narrow minded thinking would tell me that all galaxies are kinda cone shaped and if we were dirrectly in the otehr side of the galaxy we would not even see it because it is all within the cone so all we would see is empty space?&nbsp;&nbsp;&nbsp; Anyway just thought i would askk thx.&nbsp;&nbsp; &nbsp; <br />Posted by unseen</DIV></p><p>NGC 3310:</p><p><br /><img src="http://sitelife.space.com/ver1.0/Content/images/store/9/2/8954d9f6-4b90-443c-b2e9-cbc3d19f01eb.Medium.jpg" alt="" /><br />&nbsp;</p><p><br />I'm having a hard time following you. </p><p>We see all galaxies who's light has had enough time to reach us within the lifespan of the universe (about 13.7 billion years). What do you mean all galaxies are cone shaped? </p> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

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#### unseen

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So with most galaxies having a black hole in the center of them im assuming most of the mass is in the center and making a cone shape of the galaxy.&nbsp;&nbsp; like when you see a picture descriping relativity it will show a planet bending spacetime..... I would assume this would happen on an even greater scals with a galaxy and with the black hole in the center creating a cone shape or funnel shaped ?&nbsp;&nbsp; So if you are looking at the back of the funnel you are only seeing a small portion of it.&nbsp;&nbsp; and if you are looking at the front of the funnel you can see everything inside ?&nbsp;&nbsp;&nbsp; <div class="Discussion_UserSignature"> </div>

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#### MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>So with most galaxies having a black hole in the center of them im assuming most of the mass is in the center and making a cone shape of the galaxy.&nbsp;&nbsp; like when you see a picture descriping relativity it will show a planet bending spacetime..... I would assume this would happen on an even greater scals with a galaxy and with the black hole in the center creating a cone shape or funnel shaped ?&nbsp;&nbsp; So if you are looking at the back of the funnel you are only seeing a small portion of it.&nbsp;&nbsp; and if you are looking at the front of the funnel you can see everything inside ?&nbsp;&nbsp;&nbsp; <br />Posted by unseen</DIV><br /><br />You appear to be confused. As far as a galaxy is concerned, a black hole is the same as the mass spread out among a hundred thousand stars very close to the center. Once you get a few light years away, all that matters is the amount of mass there. A black hole is nothing special until you get very (or too) close. It is a very small part of the mass of a galaxy. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>So with most galaxies having a black hole in the center of them im assuming most of the mass is in the center and making a cone shape of the galaxy.&nbsp;&nbsp; like when you see a picture descriping relativity it will show a planet bending spacetime..... I would assume this would happen on an even greater scals with a galaxy and with the black hole in the center creating a cone shape or funnel shaped ?&nbsp;&nbsp; So if you are looking at the back of the funnel you are only seeing a small portion of it.&nbsp;&nbsp; and if you are looking at the front of the funnel you can see everything inside ?&nbsp;&nbsp;&nbsp; <br />Posted by unseen</DIV></p><p>The pictures that you see of black holes are hollywood renditions designed to ellicit a response from you.&nbsp; Black holes are spherically symmetric and are not cones.&nbsp; But a 3-dimensional "hole" is hard to show on film or in a picture, so they show it as a cone -- but that is not accurate.</p><p>And as Wayne says, unless you cross the event horizon, a black hole&nbsp;will seem to you to be just an object with whatever mass there is the hole, except you will see no light coming from it.&nbsp; </p> <div class="Discussion_UserSignature"> </div>

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#### crazyeddie

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<p><span style="border-collapse:collapse;font-size:12px" class="Apple-style-span"><span style="font-weight:bold" class="Apple-style-span">As far as a galaxy is concerned, a black hole is the same as the mass spread out among a hundred thousand stars very close to the center. Once you get a few light years away, all that matters is the amount of mass there. A black hole is nothing special until you get very (or too) close. It is a very small part of the mass of a galaxy.</span></span></p><p>But on the other hand, the mass of the central black hole may actually help determine the actual appearance of the entire galaxy, since it seems to affect how tightly wound the galaxy's spiral arms will be:</p><p><span style="border-collapse:collapse;font-size:12px" class="Apple-style-span"></span></p><p style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin-top:13px;margin-right:0px;margin-bottom:13px;margin-left:0px"><span style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin:0px"><span style="font-style:italic" class="Apple-style-span">As if in a cosmic hug, the spiral arms of some galaxies wrap around themselves more tightly than others. The key to the bear hug: Galaxies holding heftier black holes at their centers also have more tightly wound spiral arms, an astronomer announced today.</span></span></p><p style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin-top:13px;margin-right:0px;margin-bottom:13px;margin-left:0px">&nbsp;</p><p style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin-top:13px;margin-right:0px;margin-bottom:13px;margin-left:0px"><span style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin:0px"><span style="font-style:italic" class="Apple-style-span">The finding gives astronomers a way to weigh so-called supermassive&nbsp;</span><span style="font-style:italic" class="Apple-style-span">black holes</span><span style="font-style:italic" class="Apple-style-span">, which can have masses of millions to billions that of the sun, and are thought to reside at the centers of galaxies.</span></span></p><p style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin-top:13px;margin-right:0px;margin-bottom:13px;margin-left:0px">&nbsp;</p><p style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin-top:13px;margin-right:0px;margin-bottom:13px;margin-left:0px"><span style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin:0px"><span style="font-style:italic" class="Apple-style-span">"This is a really easy way to determine the masses of these super-massive black holes at the centers of galaxies that are very far away," said researcher Marc Seigar, an astrophysicist at the University of Arkansas at Little Rock. "This gives us a way to measure the size of these black holes out to larger distances than ever before, up to 8 billion light-years away."</span></span></p><p style="outline-style:none;outline-width:initial;outline-color:initial;border-collapse:collapse;margin-top:13px;margin-right:0px;margin-bottom:13px;margin-left:0px">http://www.space.com/scienceastronomy/080602-aas-blackhole-mass.html</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> </div>

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#### unseen

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You appear to be confused. As far as a galaxy is concerned, a black hole is the same as the mass spread out among a hundred thousand stars very close to the center. </p><p>&nbsp;</p><p>I admit it I am confused.&nbsp;&nbsp; So&nbsp;with all the matter in the center of a galaxy spacetime is wrapped very tightly around that mass in all directions is what really confuses me .......&nbsp;&nbsp; If things are falling into a black hole "persay"&nbsp;&nbsp; that wording has to be wrong matter is not falling&nbsp;into the black hole it is being pulled into the black hole/center of the galaxy and goes where?&nbsp;&nbsp; I keep hearing that black holes are the masses or you know whatever million suns so a black hole is not really a black hole it is a black 3 dimentional circle that keeps growing larger in all directions....???</p><p>Am i wrong again ?</p><p>&nbsp;I know im all over the place sorry....&nbsp;&nbsp;<br /></p> <div class="Discussion_UserSignature"> </div>

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#### origin

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You appear to be confused. As far as a galaxy is concerned, a black hole is the same as the mass spread out among a hundred thousand stars very close to the center. &nbsp;I admit it I am confused.&nbsp;&nbsp; So&nbsp;with all the matter in the center of a galaxy spacetime is wrapped very tightly around that mass in all directions is what really confuses me .......&nbsp;&nbsp; If things are falling into a black hole "persay"&nbsp;&nbsp; that wording has to be wrong matter is not falling&nbsp;into the black hole it is being pulled into the black hole/center of the galaxy and goes where?&nbsp;&nbsp; I keep hearing that black holes are the masses or you know whatever million suns so a black hole is not really a black hole it is a black 3 dimentional circle that keeps growing larger in all directions....???Am i wrong again ?&nbsp;I know im all over the place sorry....&nbsp;&nbsp; <br />Posted by unseen</DIV><br /><br /><font size="2">You are essentially right.&nbsp; A black hole has an event horizon which is approximately a spherical shape that surrounds the center of gravity.&nbsp; The event horizon is the boundry where the force of gravity exceeds the escape velocity of light.&nbsp; Anything that goes into the event horizon does not come out.&nbsp; The diameter of the event horizon is dependent on the mass of the black hole so if more matter goes into the black hole then the event horizon will get larger.</font></p><p><font size="2">The matter goes into the black hole and is squashed down to possible an infinitly small point.&nbsp; It is beyond our ability to know for sure because no usable information can come out of a black hole.</font></p><p><font size="2">The event horizon may be 'squashed' for a rotating black hole and blackholes probably do emit radiation at the event horizon but for the big picture this is rather minor.</font></p><p><font size="2">edited to add:&nbsp; all the matter is not in the blackhole at the center of a galaxy - just alot of matter, like thousands or millions of suns worth.</font></p> <div class="Discussion_UserSignature"> </div>

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#### unseen

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<br />So Basically a blackhole is X amount of matter that comes together that creates enough gravity that light cannot escape?&nbsp;&nbsp; I think but that doesn't sound right to me ?&nbsp;&nbsp; <div class="Discussion_UserSignature"> </div>

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#### MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>So Basically a blackhole is X amount of matter that comes together that creates enough gravity that light cannot escape?&nbsp;&nbsp; I think but that doesn't sound right to me ?&nbsp;&nbsp; <br />Posted by unseen</DIV><br /><br />It is not just x amount of matter. It is x amount of matter in a very small space. If the same amount of matter was spread out over a light year sized&nbsp;volume it would not be a black hole. It is only when the matter is confined to a small enough space that the density becomes great enough so that the local gravity exceeds the speed of light. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### unseen

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<p>OK great I actually understand something then.&nbsp;&nbsp;I think&nbsp; haha&nbsp;&nbsp; &nbsp;Thx.</p><p>So then could I assume when a black hole is first formed that none of the lighter elements are involved in the creation of a black hole?&nbsp;&nbsp; </p><p>&nbsp;And then assuming when a super massive star blows up the lighter elements blow away further then the heavier ones, and when gravity starts to pull everything together again the heavier elements get there first and now that sun/whatever it is now&nbsp;takes up much less space with about the same amount of weight creating a black hole?&nbsp;&nbsp; </p> <div class="Discussion_UserSignature"> </div>

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#### MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>OK great I actually understand something then.&nbsp;&nbsp;I think&nbsp; haha&nbsp;&nbsp; &nbsp;Thx.So then could I assume when a black hole is first formed that none of the lighter elements are involved in the creation of a black hole?&nbsp;&nbsp; &nbsp;And then assuming when a super massive star blows up the lighter elements blow away further then the heavier ones, and when gravity starts to pull everything together again the heavier elements get there first and now that sun/whatever it is now&nbsp;takes up much less space with about the same amount of weight creating a black hole?&nbsp;&nbsp; <br />Posted by unseen</DIV><br /><br />It doesn't make any difference whatsoever what the elements are. It's just enough mass in a small enough space. For example, it has been suggested (though not for sure) that mini black holes may be created by the LHC, and may regularly be created in our own atmosphere by cosmic rays. They would be so light that if one passed through you you wouldn't even feel it, but since the small mass there&nbsp;in would be in such a small space, they would still be black holes.</p><p>MW</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>So Basically a blackhole is X amount of matter that comes together that creates enough gravity that light cannot escape?&nbsp;&nbsp; I think but that doesn't sound right to me ?&nbsp;&nbsp; <br />Posted by unseen</DIV></p><p>A black hole is simply the result of an extremely high density of matter.&nbsp; A density so high that <u>locally</u> space-time is warped so strongly that light cannot escape.</p><p>Think of it this way.&nbsp; If you calculate the escape velocity of a planet, what you do is look the energy required, per unit mass, to move a body from the <u>surface</u>&nbsp; of the planet to infinity.&nbsp; You do that by integrating the force, which obeys and inverse square law, from the radius at the surface R to infinity.&nbsp; That integral is a finite number.&nbsp; You then calculae the escape velocity required to provide that energy in the form of kinetic energy in the simple form 1/2 mv^2.</p><p>But if the initial radius R were 0, then the integral would be infinite.&nbsp; And if the radius is larger than zero, but very small then the escape velocity is equal to the speed of light.&nbsp; At than point even light does not escape.&nbsp;Since nothing can go faster than light, there is no "escape velocity" for a body of the given mass with such a small radius.&nbsp; Now I am mixing classical and relativistic physics here, and when you add in relativity, not only can matter and light not escape to infniity, it cannot get beyond the radius at which the escape velocity is equal to the speed of light -- the Schwarzchild radius.</p><p>The point here is that what forms a black hole is not a huge mass per se, but a huge mass density.&nbsp; If the Earth were compressed to about 3 km it too would form a black hole.&nbsp; http://en.wikipedia.org/wiki/Event_horizon</p><p>Any mass, sufficiently compressed would form a black hole.&nbsp; But beyond the event horizon, a black&nbsp; hole is simply just another mass that has a rather ordinary gravitational field.&nbsp; So a black hole has neither more nor less gravitational attraction for an object outside of the event horizon than any other body.&nbsp; You can fall into a black hole in exactly the same way that you can fall towards the Earth.&nbsp; </p> <div class="Discussion_UserSignature"> </div>

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#### unseen

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<p>So what i am&nbsp;hearing/thinking&nbsp;&nbsp;then is that in every atom there is something in there that has enough mass that is small enough to create a black hole ?&nbsp;&nbsp; &nbsp;If this is not the case, &nbsp;that it is in every atom how would you compress matter enough to create the black hole?&nbsp;&nbsp;&nbsp;&nbsp;could spacetime has different properties ?&nbsp;&nbsp; Is it weaker/thinner in some area's than others ?&nbsp; Wow i am way over my head but i want to try to understand.&nbsp;&nbsp;&nbsp; Can you weigh spacetime?&nbsp;&nbsp; It would seem to me that it weighs more than matter?&nbsp;&nbsp; And the weight of whatever creates a black hole breaks the link that spacetime is all connected for a certain amount of time until it can repair itself.&nbsp;&nbsp; And you have spacetime wrapped all around itself pulling in more and more matter then breaking more links until finally it does repair it's self?&nbsp; kinda of like if you put something to heavy on a trampolene and the springs broke the trampolene would be flayling all over itself pulling everything it can into it,&nbsp; but instead of springs you have whatever links spacetime together....?????</p> <div class="Discussion_UserSignature"> </div>

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#### Bflowing

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>So what i am&nbsp;hearing/thinking&nbsp;&nbsp;then is that in every atom there is something in there that has enough mass that is small enough to create a black hole ?&nbsp;&nbsp; &nbsp;If this is not the case, &nbsp;that it is in every atom how would you compress matter enough to create the black hole?&nbsp;&nbsp;&nbsp;&nbsp;could spacetime has different properties ?&nbsp;&nbsp; Is it weaker/thinner in some area's than others ?&nbsp; Wow i am way over my head but i want to try to understand.&nbsp;&nbsp;&nbsp; Can you weigh spacetime?&nbsp;&nbsp; It would seem to me that it weighs more than matter?&nbsp;&nbsp; And the weight of whatever creates a black hole breaks the link that spacetime is all connected for a certain amount of time until it can repair itself.&nbsp;&nbsp; And you have spacetime wrapped all around itself pulling in more and more matter then breaking more links until finally it does repair it's self?&nbsp; kinda of like if you put something to heavy on a trampolene and the springs broke the trampolene would be flayling all over itself pulling everything it can into it,&nbsp; but instead of springs you have whatever links spacetime together....????? <br />Posted by unseen</DIV><br /><br />I'm only a layman, but it takes more than single item to create a black hole.&nbsp; Gravity can cause light to bend, that has been shown.&nbsp; Increase the gravity and eventually you reach a point where light just doesn't bend, but gets trapped.&nbsp; Gravity will cause atoms to compress, but it also depends on the element.&nbsp; Compress hydrogen, and it fuses to helium creating energy which stops the compression.&nbsp;(That's what our star does.)&nbsp; However, compress iron and no new energy is created, thus leading to a possibility (if enough mass) to create a black hole.</p><p>My question is what happens to all those photons that constantly flow into a black hole. Do they stay as energy, or convert to matter?&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> </div>

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#### MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'm only a layman, but it takes more than single item to create a black hole.&nbsp; Gravity can cause light to bend, that has been shown.&nbsp; Increase the gravity and eventually you reach a point where light just doesn't bend, but gets trapped.&nbsp; Gravity will cause atoms to compress, but it also depends on the element.&nbsp; Compress hydrogen, and it fuses to helium creating energy which stops the compression.&nbsp;(That's what our star does.)&nbsp; However, compress iron and no new energy is created, thus leading to a possibility (if enough mass) to create a black hole.Posted by Bflowing</DIV><br /><br />An atom does not have enough mass to compress to the point of creating a black hole. Black holes are created at incredible densities where atoms do not exist, protons and neutrons do not exist. They are crushed beyond that point.</p><p>All that is left is mass.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### Saiph

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<p>Bflowing:&nbsp; Once they cross the event horizon...there is no distinction between energy and matter.&nbsp; As energy can be equated to mass, they are the same thing once inside the BH.&nbsp; The photons will add to the total energy/matter density, and increase the gravity of the BH.</p><p>The only characteristics that remain of objects that fall into a BH are mass, charge and spin.&nbsp; So we can't tell the difference between a BH of photons, or of peanut butter. </p> <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

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#### MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Bflowing:&nbsp; Once they cross the event horizon...there is no distinction between energy and matter.&nbsp; As energy can be equated to mass, they are the same thing once inside the BH.&nbsp; The photons will add to the total energy/matter density, and increase the gravity of the BH.The only characteristics that remain of objects that fall into a BH are mass, charge and spin.&nbsp; So we can't tell the difference between a BH of photons, or of peanut butter. <br />Posted by Saiph</DIV><br /></p><p>&nbsp;</p><p>Mmmmmm,peanut butter..{drool}</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### Bflowing

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>An atom does not have enough mass to compress to the point of creating a black hole. Black holes are created at incredible densities where atoms do not exist, protons and neutrons do not exist. They are crushed beyond that point.All that is left is mass. <br />Posted by MeteorWayne</DIV><br /><br />Thanks for the info, I really appreciate it.&nbsp; But am I still correct that it only happens when fusion will no longer&nbsp;create energy?</p><p>Now I assume when matter falls into the BH, its "power" or reach is increased.&nbsp; But what about light?&nbsp; If photons have no mass, do they affect the size of the BH?</p> <div class="Discussion_UserSignature"> </div>

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#### DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>An atom does not have enough mass to compress to the point of creating a black hole. Black holes are created at incredible densities where atoms do not exist, protons and neutrons do not exist. They are crushed beyond that point.All that is left is mass. <br />Posted by MeteorWayne</DIV></p><p>I'm glad you said that.&nbsp; It is food for thought.</p><p>I think you are wrong.&nbsp; Black holes are formed by mass density, not so much by mass per se. I don't think we know enough about the&nbsp; singularity in a black hole to know if atoms, protons or neutrons exist near it.&nbsp; But it is certainly true that atoms do not form black holes.&nbsp; The question is why not ?</p><p>The elementary particles are treated as points in modern quantum field theories.&nbsp; And most of them have mass.&nbsp; So the mass density would be infinite. That ought to be&nbsp;enough for a small black hole.&nbsp; It also ought to evaporate quickly due to Hawking radiation. &nbsp; But then, of course, quantum theory tells us that we cannot actually say where that point is.&nbsp; So maybe density in the quantum sense doesn't make much sense.&nbsp; There is a puzzle here.</p><p>This might be at the heart of why quantum mechanics and general relativity are so difficult to unify.&nbsp; But I am not smart enough to be able to figure out what this is trying to tell us.</p><p>I'm glad you provided this puzzle.&nbsp; It is worth thinking about.&nbsp; It is enough to make my head hurt -- a good kind of hurt though.<br /></p> <div class="Discussion_UserSignature"> </div>

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#### MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'm glad you said that.&nbsp; It is food for thought.I think you are wrong.&nbsp; Black holes are formed by mass density, not so much by mass per se. I don't think we know enough about the&nbsp; singularity in a black hole to know if atoms, protons or neutrons exist near it.&nbsp; But it is certainly true that atoms do not form black holes.&nbsp; The question is why not ?The elementary particles are treated as points in modern quantum field theories.&nbsp; And most of them have mass.&nbsp; So the mass density would be infinite. That ought to be&nbsp;enough for a small black hole.&nbsp; It also ought to evaporate quickly due to Hawking radiation. &nbsp; But then, of course, quantum theory tells us that we cannot actually say where that point is.&nbsp; So maybe density in the quantum sense doesn't make much sense.&nbsp; There is a puzzle here.This might be at the heart of why quantum mechanics and general relativity are so difficult to unify.&nbsp; But I am not smart enough to be able to figure out what this is trying to tell us.I'm glad you provided this puzzle.&nbsp; It is worth thinking about.&nbsp; It is enough to make my head hurt -- a good kind of hurt though. <br />Posted by DrRocket</DIV><br /><br />Indeed, while they are treated as points, they must not actually be or they would have infinite mass Edit= mass density, thanx DrR, mistyped ).</p><p>Maybe we just proved string theory? </p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Indeed, while they are treated as points, they must not actually be or they would have infinite mass.Maybe we just proved string theory? <br />Posted by MeteorWayne</DIV></p><p>Not infinite mass, but infnite mass density. The mass is actually known and quite small. But if the volume is zero, the density is infinte.&nbsp; It is mass density and not mass itself that cause black holes to form.&nbsp; And very small black holes, if they exist may be driven by quantum behavior (Hawking radiation) that is a small effect on big black holes.</p><p>There is wee problem with the electron model.&nbsp; If you model an electron as a point (and that is what is done) then you calculate the self-energy and find that it is infinite.&nbsp; Now from relativity, infinite energy means infinite mass.&nbsp; Yes, there is a contradiction here.&nbsp; It is hard for the electron mass to be very small and infinite at the same time.</p><p>The situation is actually worse.&nbsp; If you don't model the electron as a point then you get other contradictions.&nbsp; And string theory has its own set of inconsistencies.</p><p>The bottom line is that we just don't know.&nbsp; It may well be that volume and mass density are simply not definable in the quantum world.&nbsp; <br /></p> <div class="Discussion_UserSignature"> </div>

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#### unseen

##### Guest
Ok this makes me think of....&nbsp;&nbsp; How do you measure mass density ??&nbsp; You can weigh something only if something else is holding it up?&nbsp;&nbsp; If you get to a point to where nothing is holding it up is there any density or mass for that matter&nbsp;&nbsp; (haha)?&nbsp;&nbsp; Very confusing the words "holding it up" are.....&nbsp;&nbsp;mass warps space time around it does that mean spacetime is holding up mass and when mass reaches a certain mass density spacetime can no longer hold it up ?&nbsp;&nbsp; And since it cannot go "down" or "up" it would have to be equal on all sides where does it go ?&nbsp;&nbsp;&nbsp; another demesion ?&nbsp;&nbsp; <div class="Discussion_UserSignature"> </div>

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#### DrRocket

##### Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ok this makes me think of....&nbsp;&nbsp; How do you measure mass density ??&nbsp; You can weigh something only if something else is holding it up?&nbsp;&nbsp; If you get to a point to where nothing is holding it up is there any density or mass for that matter&nbsp;&nbsp; (haha)?&nbsp;&nbsp; Very confusing the words "holding it up" are.....&nbsp;&nbsp;mass warps space time around it does that mean spacetime is holding up mass and when mass reaches a certain mass density spacetime can no longer hold it up ?&nbsp;&nbsp; And since it cannot go "down" or "up" it would have to be equal on all sides where does it go ?&nbsp;&nbsp;&nbsp; another demesion ?&nbsp;&nbsp; <br />Posted by unseen</DIV></p><p>You can determine mass either by measuring the effect of a known gravitational field (weight) or be determining inertia the resistance of a massive body to acceleration (inertial mass).&nbsp; So far as is known and there have been some very precise experiments to evaluae this, inertial mass and gravitational mass are equal.&nbsp; To ge mass density then you simply divide the mass by the volume.&nbsp; <br /></p> <div class="Discussion_UserSignature"> </div>

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