Post by: @/antic on 09/04/2012 08:12:02
Any ideas?
Post by: yor_on on 09/04/2012 10:11:26
But when that black hole once can exist at all, all 'mass' is defined to a dimensionless point inside it as I understands it. So there are no more interactions from / in that mass, only a 'gravity'. And the spatial dimensions might become very large, as described from the inside of such a 'black hole', even 'infinite', well, depending on your mathematical definitions and what kind of black hole you envision.
If you assume that there still is some slight volume defining that mass though?
I don't know?
But if mass is a equivalence of 'energy'?
Post by: @/antic on 09/04/2012 20:07:06
Yes, indeed, the compression of matter into a point must be accompanied by enormous amounts of friction and the kinetic energy of the matter would be transformed into heat.
I’m thinking mainly about the supermassive black holes at the centres of galaxies. Heat is dissipated through x-rays? And surely this must be correlated to the mass of the Black Hole? So, what would be the temperature of the Black Hole?
Do you think that matter is able to move into other spatial dimensions through Black Holes, and would this still be consistent with the Law of conservation of energy?
Cheers,
Atlantic
Post by: Nizzle on 10/04/2012 07:35:38
Post by: MikeS on 10/04/2012 08:06:29
Post by: syhprum on 10/04/2012 09:18:30
Post by: MikeS on 10/04/2012 10:51:05
It seems a rather meaningless question as the normal definition of temperature does not seem to apply to the insides of black holes but my guess would be the planck temperature of 1.416833 × 10^32°K
"Current cosmological models postulate that the highest possible temperature is the Planck temperature, which has the value 1.416785(71)×1032 kelvin.[3] The Planck temperature is assumed to be the highest temperature in conventional physics because conventional physics breaks down at that temperature. Above ~1032K, particle energies become so large that there is no existing scientific theory for the behavior of matter at these energies. Gravitational forces between them would become as strong as other fundamental forces,"
http://en.wikipedia.org/wiki/Absolute_hot
Would that mean that gravity was infinite? If so then time should stop which is what happens at absolute zero.
So is absolute hot, the same as absolute cold?
(Imagine a line with cold at one end and hot at the other. Now form it into a loop.)
Think I'm going to give up on this one!
Post by: Nizzle on 10/04/2012 11:02:59
It seems a rather meaningless question as the normal definition of temperature does not seem to apply to the insides of black holes but my guess would be the planck temperature of 1.416833 × 10^32°K
... which occurs at QGP :o
Post by: yor_on on 10/04/2012 11:33:44
As soon as it has, assuming that the inside of a black hole have a 'space' too, it should follow a geodesic. Now, when following a 'accelerating gravitational' geodesic, does the object give of heat in a empty space?
Not that I know. So as long as the geodesics are unique for each object infalling and they don't intersect in time and space there should be no radiation, as I think of it now?
Any x-rays etc, we see are phenomena happening outside a event horizon, most of them due to black holes rotating incredibly close to lights speed in a vacuum. I don't think we cataloged any Black hole, yet, that's not rotating? Doesn't mean there can't be though.
And a Black Hole is not supposed to be 'warmer' than the surrounding 'space' outside it, as I understands it, it is supposed to be colder actually :)
Post by: yor_on on 10/04/2012 11:45:34
I don't know myself.
Take a look here (http://www.answers.com/topic/albert-einstein#wormholes), follow the links to 'wormholes', and then decide for yourself :)
"Einstein collaborated with others to produce a model of a wormhole. His motivation was to model elementary particles with charge as a solution of gravitational field equations, in line with the program outlined in the paper "Do Gravitational Fields play an Important Role in the Constitution of the Elementary Particles?". These solutions cut and pasted Schwarzschild black holes to make a bridge between two patches.
If one end of a wormhole was positively charged, the other end would be negatively charged. These properties led Einstein to believe that pairs of particles and antiparticles could be described in this way."
Post by: Nizzle on 10/04/2012 12:05:16
As soon as it has, assuming that the inside of a black hole have a 'space' too, it should follow a geodesic. Now, when following a 'accelerating gravitational' geodesic, does the object give of heat in a empty space?
I think there will be multiple geodesics to follow as the object will be under such a gravitational stress that it's ripped apart. Now, if a black hole would be a ball of GQP in the centre, the temperature would be at Planck scale, at which point gravity becomes as strong as the other 3 fundamental forces. If we then look at a single atom falling into the Event Horizon, the pull on the atomic nucleus will be much harder than on the electrons, so the atomic nucleus will be absorbed in the ball of GQP well before the electrons who will eventually follow. These separations of nuclei and their electrons might give off radiation, and the collision of the nucleus with the GQP might give off radiation and the subsequent collision of the electrons with the GQP might also give off radiation. Since we're dealing with such extreme conditions, we don't even know if all of these radiations are photon based, but that it could be gluon or W or Z boson based radiation as well. All these processes could generate heat as byproduct, keeping the temperature near or at planck temperature..
Post by: yor_on on 10/04/2012 13:04:56
I still don't know which will be true. Are there 'tidal forces' inside that possibly expanded 'space'? You might want to argue that we too could be seen as 'existing' inside a 'Black Hole', or spewed out from a 'White Hole', whatever tickles ones imagination :) and whatever makes one define what a 'space(time)' is.
==
Spaghettification. (http://en.wikipedia.org/wiki/Spaghettification)
=
As for making a Quark Gluon Plasma?
I don't think the gravity is strong enough at the event horizon. Try to calculate what force you would need to rip an atom into its constituents and then tell me :) Then you just need to calculate what the gravity's potential needs to be. Maybe if you were very close to a 'center' of a Black Hole though? But if being so close?
There we might get our 'radiation' in a Big Bang :)
Pure 'energy' that (somehow) must interact to 'fuse' into 'particles' of mass.
I like that idea, although it makes little sense, as it becomes a yo-yo effect presuming something always preexisting for it to be created from. A truly 'cyclic' universe.
Post by: MikeS on 10/04/2012 15:34:53
I think a black hole at the end of our universe cycle becomes a white hole (quasar) at the start of the next.
Post by: syhprum on 10/04/2012 16:25:49
Perhaps some more mathematical competent correspondent could refine these figures.
Post by: yor_on on 10/04/2012 18:00:36
So that center may have a he* of a lot of bosons, but no particles of rest mass. And as the 'point' there is assumed to be dimensionless? Without a way to communicate with SpaceTime, how do they tell that there must be a 'gravity'?
Post by: Æthelwulf on 11/04/2012 00:55:10
If you looked at the density of a black hole from inside, it would seem less inside than being an observer who was looking outside of it.
Post by: @/antic on 12/04/2012 11:22:55
Really interesting responses and lots of food for thought!!
Thanks. :)
Atlantic
Post by: Æthelwulf on 12/04/2012 23:49:47
Hi
Any ideas?
Depends on the size. Small black holes are very very hot. Large black holes are relatively cold.
Post by: Æthelwulf on 12/04/2012 23:50:32
Hi
Any ideas?
Depends on the size. Small black holes are very very hot. Large black holes are relatively cold.
And from where you look, but that is very technical and I don't exactly know why I said that first.
Post by: MikeS on 14/04/2012 06:47:09
(Submitted November 11, 1997)
What is the temperature of a black hole?
The Answer
The temperature of a black hole is determined by the 'black body radiation temperature' of the radiation which comes from it. (e.g., If something is hot enough to give off bright blue light, it is hotter than something that is merely a dim red hot.)
For black holes the mass of our Sun, the radiation coming from it is so weak and so cool that the temperature is only one ten-millionth of a degree above absolute zero. This is colder than scientists could make things on Earth up until just a few years ago (and the invention of of a way to get things that cold won the Nobel prize this year). Some black holes are thought to weigh a billion times as much as the Sun, and they would be a billion times colder, far colder than what scientists have achieved on Earth.
However, even though these things are very cold, they can be surrounded by extremely hot material. As they pull gas and stars down into their gravity wells, the material rubs against itself at a good fraction of the speed of light. This heats it up to hundreds of millions of degrees. The radiation from this hot, infalling material is what high-energy astronomers study.
David Palmer
for Ask an Astrophysicist"
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/971111e.html
The above refers to the temperature of the outside of a black hole.
The information barrier stops us from knowing what is happening on the inside.
A black hole by definition is an area of space-time with a gravitational field so intense that its escape velocity is equal to or exceeds the speed of light. A super-massive black hole can have a density less than the density of water. http://en.wikipedia.org/wiki/Super-massive
The larger the radius of it's event horizon, the less dense it need be. This does not imply that large black holes have to be hot. The Universe fits the definition of a black hole as it is gravitationally bound. It's temperature is only 2.75 degrees kelvin above absolute zero. That's cold.
Post by: @/antic on 15/04/2012 19:35:34
Brilliant!
Thanks everyone
Post by: Soul Surfer on 16/04/2012 19:02:50
Taking this concept a little further. As the succession of event horizons get smaller and the gravity gradient gets greater the Hawking radiation will get stronger until it is strong enough to soak up all the energy in the hole that is the Hawking radiation from the horizon together with the time it takes to fall back into the hole represents all the energy in the hole. This is a first bash at a serious proof of what is inside a simple scwartschild black hole. It is not a "new theory" it is just based on what we currently agree upon and I challenge someone to prove it wrong!
Post by: MikeS on 17/04/2012 08:48:52
clip
Taking this concept a little further. As the succession of event horizons get smaller and the gravity gradient gets greater the Hawking radiation will get stronger until it is strong enough to soak up all the energy in the hole that is the Hawking radiation from the horizon together with the time it takes to fall back into the hole represents all the energy in the hole. This is a first bash at a serious proof of what is inside a simple scwartschild black hole. It is not a "new theory" it is just based on what we currently agree upon and I challenge someone to prove it wrong!
I don't follow the logic of this. Hawkin radiation only operates on the outside of the first (outermost) event horizon and is unaffected by anything inside the event horizon. How can it 'soak up' what can't reach it?
On the other hand, if matter and antimatter should prove to be repulsive then a black hole could emit antimatter particles from inside the EH.
Post by: imatfaal on 17/04/2012 09:26:35
The original question was what is the temperature INSIDE a black hole. Now we do not know this but assuming that the hole is quiet i.e. There isn't lots of stuff falling into it. It will also be very cold just inside the event horizon because as the stuff inside contracts towards, whatever it is (certainly NOT a mathematical singularity), the gravitational field will increase and photons from the centre of the contraction will not be able make it even to just inside the first event horizon. So there will in effect be whole series of event horizons inside each smaller and warmer than the last.Why is it quantised SSurfer? Event horizons are cut-offs - I can see no reason for abrupt demarcations within the EH rather a gradual spectrum. As this is GR based - to get a quantisation you need a form of quantum gravity, or do you intend that this would lead to QG?
Quote
Taking this concept a little further. As the succession of event horizons get smaller and the gravity gradient gets greater the Hawking radiation will get stronger until it is strong enough to soak up all the energy in the hole that is the Hawking radiation from the horizon together with the time it takes to fall back into the hole represents all the energy in the hole. This is a first bash at a serious proof of what is inside a simple scwartschild black hole. It is not a "new theory" it is just based on what we currently agree upon and I challenge someone to prove it wrong!So you end up with a shell (or a sphere) of radiation at an interior EH corresponding with the total mass/energy of the BH? The mass/energy of the BH is constantly and completely emitted via Hawking Radiation (the interior EHs acting as would a smaller BH - smaller=hotter) but this radiation would be entirely internal.
My problem is that I cannot see why you can postulate the interior EHs! Once you have the interior EH then you can go onwards - but why are they there at all?
Post by: Æthelwulf on 17/04/2012 10:39:54
The original question was what is the temperature INSIDE a black hole. Now we do not know this but assuming that the hole is quiet i.e. There isn't lots of stuff falling into it. It will also be very cold just inside the event horizon because as the stuff inside contracts towards, whatever it is (certainly NOT a mathematical singularity), the gravitational field will increase and photons from the centre of the contraction will not be able make it even to just inside the first event horizon. So there will in effect be whole series of event horizons inside each smaller and warmer than the last.Why is it quantised SSurfer? Event horizons are cut-offs - I can see no reason for abrupt demarcations within the EH rather a gradual spectrum. As this is GR based - to get a quantisation you need a form of quantum gravity, or do you intend that this would lead to QG?QuoteTaking this concept a little further. As the succession of event horizons get smaller and the gravity gradient gets greater the Hawking radiation will get stronger until it is strong enough to soak up all the energy in the hole that is the Hawking radiation from the horizon together with the time it takes to fall back into the hole represents all the energy in the hole. This is a first bash at a serious proof of what is inside a simple scwartschild black hole. It is not a "new theory" it is just based on what we currently agree upon and I challenge someone to prove it wrong!So you end up with a shell (or a sphere) of radiation at an interior EH corresponding with the total mass/energy of the BH? The mass/energy of the BH is constantly and completely emitted via Hawking Radiation (the interior EHs acting as would a smaller BH - smaller=hotter) but this radiation would be entirely internal.
My problem is that I cannot see why you can postulate the interior EHs! Once you have the interior EH then you can go onwards - but why are they there at all?
I can tell you why. The interior boundaries are created from space and time switching coordinates. I could show you math which explains how space and time switch roles... it doesn't really mean that space is really time and time is really space now, it's just a coordinate phenomena.
The gravitational effects of a black hole become so strong at the horizon, that space and time switch roles: space becomes timelike and time becomes spacelike. Then somewhere inside the black holes, these artefacts change back to normal and it will be here you find the inner boundary. With that said, Sean Carrol is dedicting a lot of his time to weild the idea that we are living inside a black hole, and I can only presume it would be inside the interior where space and time are acting normally again.
Post by: yor_on on 17/04/2012 12:53:48
For a Schwarzwild non rotating black hole if I remember right.
Or can you use it for rotating ones too?
Post by: Æthelwulf on 17/04/2012 14:01:20
Isn't that one only for one kind of solution Wulf?
For a Schwarzwild non rotating black hole if I remember right.
Or can you use it for rotating ones too?
Yes, you are right. The solutions which permit these conditions are calculated from the Schwarzchild metric.
Post by: Soul Surfer on 18/04/2012 00:04:41
Consider the stuff at the instant the first event horizon forms. THE EH is the point where the escape velocity becomes equal to the velocity of light and escape to "infinity" is not possible. Now wait a bit and let the stuff collapse a little further. No more stuff is falling in so there is an empty space between the collapsing stuff and the EH. Now this smaller blob has a higher gravitational field but escape for a short distance before falling back IS possible. Stuff then escape a bit but there will be a gap to the event horizon. This is an inner collapsing "event horizon" of a type. Exactly the same quantum rules would apply it is possible for radiation to be emitted from that level but it would of course eventually fall back to the centre but it takes time doing this. This inner horizon will shrink and become hotter as it gets smaller. OK it will have to shrink to be pretty small before it gets hot enough. The classic black hole anlaysis site http://xaonon.dyndns.org/hawking/ says it will be about 10^-9 the size of an atomic nucleus before it gets to radiate as much energy as the sun. At the Planck length it is 10^21 times that of the sun. (Mathematical singularities are still infinitely smaller than this and there is no limit to the energy in theory). A quick estimate of the amount of energy in our universe is around 10^10 galaxies with around 10^10 stars plus about 10-100 times as much dark stuff that makes around 10^21 give or take an order of magnitude or two. So collapse to the Planck limit would produce an incredibly hot blob continually radiating and reabsorbing about as much energy as a whole universe. Interesting!
Again I stress this is not a new theory and comes directly from applying the totally accepted rules. the end result is not a mathematical singularity but a simple model that makes sense just by looking at what we know today.
Æthelwulf I agree and would go further to suggest that space and time actually DO change places and as the space contracts to a time line (Kerr black hole with ring singularity) that time expands to become multi dimensional space in a new universe seeded when the black hole collapsed (but that is a new theory and should not really be mentioned here.) Penrose and his diagrams tends to assume that to get to a new universe via a black hole you have to do another reversal of space and time to restore the status quo but I do not think that this is really essential.
Post by: MikeS on 22/04/2012 08:36:22
Differences in gravitational potential would normally imply different time dilation factors but at the event horizon time is already infinitely dilated (time stands still).
Time can't go any slower inside the EH. Maybe time reverses direction. That would account for why something that is very hot from one reference point is actually very cold from another. Maybe from a time reversed reference frame within the EH, black body radiation of the black hole is seen from the outside as black-body absorbtion.
Obviously, this is pure speculation as we have little idea of the physics of black holes.
added
The above would seem to be in keeping with my reply #6 in this thread.
"So is absolute hot, the same as absolute cold?"
Post by: MikeS on 28/04/2012 08:35:14
I can tell you why. The interior boundaries are created from space and time switching coordinates. I could show you math which explains how space and time switch roles... it doesn't really mean that space is really time and time is really space now, it's just a coordinate phenomena.
The gravitational effects of a black hole become so strong at the horizon, that space and time switch roles: space becomes timelike and time becomes spacelike. Then somewhere inside the black holes, these artefacts change back to normal and it will be here you find the inner boundary. With that said, Sean Carrol is dedicting a lot of his time to weild the idea that we are living inside a black hole, and I can only presume it would be inside the interior where space and time are acting normally again.
Is it possible that space and time switching coordinates is the same as the arrow of time reversing?
It would account for "space and time acting normally again".
Post by: Æthelwulf on 28/04/2012 09:24:53
I can tell you why. The interior boundaries are created from space and time switching coordinates. I could show you math which explains how space and time switch roles... it doesn't really mean that space is really time and time is really space now, it's just a coordinate phenomena.
The gravitational effects of a black hole become so strong at the horizon, that space and time switch roles: space becomes timelike and time becomes spacelike. Then somewhere inside the black holes, these artefacts change back to normal and it will be here you find the inner boundary. With that said, Sean Carrol is dedicting a lot of his time to weild the idea that we are living inside a black hole, and I can only presume it would be inside the interior where space and time are acting normally again.
Is it possible that space and time switching coordinates is the same as the arrow of time reversing?
It would account for "space and time acting normally again".
You do realize that I don't believe an arrow of time exists? I won't go into the reasons why, but I should state that time is not linear - and for this reason, the whole idea of the coordinate change might be a load of rubbish.
In some loose way of speaking about this coordinate transformation, Space becomes Timelike, but what does that mean?
Well, in the view of mathematics, time goes one way: it looks like an arrow to us, because everything has a forward directionality, we never see things going back in time. Because of this, we humans often project this phenomenon subjectively and believe that time has some ''linearity'' about it. Well, when we say that space has become timelike, we mean that we are now [moving in space] as if we were linearly moving through time. This means we cannot move to the sides, we cannot move backwards.
We can however begin to move through time very freely. We may in fact, oscillate in time. This would mean there is no preferred directionality and this is what we mean when time becomes spacelike.
So as for time being viewed linear, that is dubious and the greater collection of physicists today don't believe that time flows linearly like a river. However, even with that said, even in the view of time being spacelike, linearity is not preserved, you may oscillate in the time dimenion.
Post by: Æthelwulf on 28/04/2012 22:26:41
Numerous event horizons at different gravitational potential?Take what I said above as true... but there was something else I realized just there.
Differences in gravitational potential would normally imply different time dilation factors but at the event horizon time is already infinitely dilated (time stands still).
Time can't go any slower inside the EH. Maybe time reverses direction. That would account for why something that is very hot from one reference point is actually very cold from another. Maybe from a time reversed reference frame within the EH, black body radiation of the black hole is seen from the outside as black-body absorbtion.
Obviously, this is pure speculation as we have little idea of the physics of black holes.
added
The above would seem to be in keeping with my reply #6 in this thread.
"So is absolute hot, the same as absolute cold?"
Time-reversed scenario's of black holes also go by another name, called white holes, but these objects spit out energy instead of sucking it in. They may not exist however because it is generally believed they violate the second law of thermodynamics.
Post by: Geezer on 29/04/2012 01:41:43
Take what I said above as true...
Mr
You do not hold a monopoly on science, so please do not tell other members to take anything as true without providing scientific proof.
Post by: Æthelwulf on 29/04/2012 02:36:55
Take what I said above as true...
MrScientistAW,
You do not hold a monopoly on science, so please do not tell other members to take anything as true without providing scientific proof.
Fine I will provide proof. I thought my time since being here has shown I know what I am talking about. Fine, if you want to have proof, I will write up the math and link sources.
Post by: Pmb on 29/04/2012 02:45:02
A scientist who knows their stuff knows enough to never use the term "true" in a sentance.
Take what I said above as true...
MrScientistAW,
You do not hold a monopoly on science, so please do not tell other members to take anything as true without providing scientific proof.
Post by: Pmb on 29/04/2012 02:49:03
Post by: Æthelwulf on 29/04/2012 02:55:12
We begin with the Schwartzschild metric, which is
The
is really just 
This describes the metric of a two dimensional sphere... and yes, I do mean two dimensional, because we are dealing with the surface or what is called, ''the local neighbourhood of a black hole.''
The local neighbourhood is in fact just as good as a flat space approximation.
is the Horizon, and any amount of ordinary time 
actually amounts to no proper time 
. Go back to the metric, when the coefficient of 
goes to zero 
we imagine this has to do with clocks running slower. When 
, we have 
naturally then the coefficient of 
on the 
- term. When 
for the 
-term, then the 
. What is worse than this, is that it blows up to infinity with a negative sign, and thus 
and 
interchange signs, they effectively switch roles. This means you will begin to move through space linearly and without recourse. Now, saying space has become timelike maybe slightly faulty, because it preassumes that time is linear. Time is not linear, in that it flows like a river from the past to the future. Next I will find references to show you this statement is what current science tells us.
Post by: Æthelwulf on 29/04/2012 02:57:53
I feel that confident with the famous George Ellis, this is all the references I need. Now, if time is not a river which extends from our past to future, then time cannot be linear. Besides, time is far from linear when you think about geometrical consequences of GR.
Post by: Æthelwulf on 29/04/2012 02:58:36
I've been a physicist for over 20 years now and one term I never use is "true" or something similar to it.
It's as true as we know it today. Do we think the curvature of spacetime is true?
If you are scared to use the word, you are not really agreeing with science.
Post by: Geezer on 29/04/2012 05:30:03
You have been warned repeatedly that you may not patronize other members.
Please do not do that again. I think you are very familiar with what will happen if you do.
Post by: MikeS on 29/04/2012 05:50:26
http://arxiv.org/abs/0812.0240
I feel that confident with the famous George Ellis, this is all the references I need. Now, if time is not a river which extends from our past to future, then time cannot be linear. Besides, time is far from linear when you think about geometrical consequences of GR.
A river always flows downhill but not always at the same rate.
If by linear you mean as in a straight line with equal divisions then from a local time frame, time is always linear. Observed from any other non-local frame then time is seldom linear unless that frame is co moving.
Post by: Æthelwulf on 29/04/2012 05:56:03
AW,
You have been warned repeatedly that you may not patronize other members.
Please do not do that again. I think you are very familiar with what will happen if you do.
Where have I patronized anyone?
Sorry Mike, I will answer you soon. I would like to be shown how I have been patronizing.
Post by: Æthelwulf on 29/04/2012 05:56:53
AW,
You have been warned repeatedly that you may not patronize other members.
Please do not do that again. I think you are very familiar with what will happen if you do.
Where have I patronized anyone?
Sorry Mike, I will answer you soon. I would like to be shown how I have been patronizing.
If you have picked me up wrong, I'd like an apology. Just like you read my last thread as a new theory here but was a question. mistakes have happened I guess.
Post by: Pmb on 29/04/2012 06:16:23
Do we think the curvature of spacetime is true?As I said above, "true" is a word I never use. In this case it is not okay to think of curvature of spacetime is true. To be precise, this is not even a poorly phrased question. In the absense of matter the spacetime will expected not to be curved. If Einstein's equations are valid and region S of spacetime is calculated to have spacetime curvature then the value of spacetime is calculated to be non-zero then the appropriate to say that the spacetime region is curved.
Now it's my turn to ask you a question. When I go out of the way to say that never is a word I use then why do you go out of your way to ask me the same question again?
If you are scared to use the word, you are not really agreeing with science.Please show me in this thread or any other thread where I said that I was scared to use? Also, please post a proof whose conclusion is that I'm not really agreeing with science.
There are only a few instances wherein it is okay to say that it is okay to conclude that something is true/false.
Correction: There actually are instances where it is okay to say something is true or false, or right or wrong. I made a mistake in saying otherwise. I've been off my game lately. This is not a result of being right or wrong. It is a result of having SSRI disorder syndrom. It's one of the reasons I haven't been posting as much as I used to.
Let me give you an example:
Correct example of when it's okay to say that something is true; Saying that the invariance of the speed of light is true is an example of when it is not okay to say that the speed of light is being invariance is true. We cannot say this as true because it is concievable that the speed of light might one day be measured to be different that c.
There are, of course, othertimes where I use the term "true" in error which I say when I simply make a mistake in saying so (being human I will of course, make an error at times).
It is also "true" to say that the number of golf balls in a bucket is three when the sum is two and I add one. It is true that the sum after adding one to make it three.
I might have made an error above because it can be quite easy to make a mistake in terminology. Be careful in making assertions like the one you ended your post with, i.e. be cautious when you claim that I am not really agreeing with science.
Post by: Æthelwulf on 29/04/2012 06:22:02
Do we think the curvature of spacetime is true?As I said above, "true" is a word I never use. In this case it is not okay to think of curvature of spacetime is true. To be precise, this is not even a poorly phrased question. In the absense of matter the spacetime will expected not to be curved. If Einstein's equations are valid and region S of spacetime is calculated to have spacetime curvature then the value of spacetime is calculated to be non-zero then the appropriate to say that the spacetime region is curved.
Now it's my turn to ask you a question. When I go out of the way to say that never is a word I use then why do you go out of your way to ask me the same question again?If you are scared to use the word, you are not really agreeing with science.Please show me in this thread or any other thread where I said that I was scared to use? Also, please post a proof whose conclusion is that I'm not really agreeing with science.
There are only a few instances wherein it is okay to say that it is okay to conclude that something is true/false.
Correction: There actually are instances where it is okay to say something is true or false, or right or wrong. I made a mistake in saying otherwise. I've been off my game lately. This is not a result of being right or wrong. It is a result of having SSRI disorder syndrom. It's one of the reasons I haven't been posting as much as I used to.
Let me give you an example:
Correct example of when it's okay to say that something is true; Saying that the invariance of the speed of light is true is an example of when it is not okay to say that the speed of light is being invariance is true. We cannot say this as true because it is concievable that the speed of light might one day be measured to be different that c.
There are, of course, othertimes where I use the term "true" in error which I say when I simply make a mistake in saying so (being human I will of course, make an error at times).
It is also "true" to say that the number of golf balls in a bucket is three when the sum is two and I add one. It is true that the sum after adding one to make it three.
I might have made an error above because it can be quite easy to make a mistake in terminology. Be careful in making assertions like the one you ended your post with, i.e. be cautious when you claim that I am not really agreeing with science.
Actually it was a poor question, because even in the absence of matter spacetime can be curved due to Einsteins equations, such as gravitational waves. They are not trivial...
I can't post a proof. I am generalizing here. Sure there are things in science we can be sure about and say is true. An apple falls because of gravity is true to current belief. What is also true is that electrons are spin 1/2 particles and that photons travel at the speed of light.
What you implied to me, was that you never use the word ''true'' in physics. What word do you use then with subjects which are well-written and experimentally-varified upon?
I don't, for instance, go around saying ''yes, possibly'' to anything which is at the core of physical understanding. If someone asked me, ''is an electron a Fermion?'' I wouldn't reply to this, ''yes maybe''. I'd say, ''yes, that is true.''
Why is that wrong?
Post by: Æthelwulf on 29/04/2012 06:22:54
Nothing is wrong with this statement.
Post by: Æthelwulf on 29/04/2012 06:41:13
AW,
You have been warned repeatedly that you may not patronize other members.
Please do not do that again. I think you are very familiar with what will happen if you do.
Can I just say for the record in case Geezer does find a reason to banish me, is that the the partonization was supposed to be in this line:
''If you are scared to use the word, you are not really agreeing with science.''
I did not however imply he was. I said ''if''. I know plenty of people in science who would say the same thing about anyone. I wouldn't dodge a question by saying ''maybe'' to a simple question like what is the spin of a fermion, is it a 1/2 spin? I wouldn't go, ''maybe''... I would say ''true''. If I said ''maybe'' it would mean to be taken that I have reservations on my answer, that I perhaps don't entirely agree with what science has to say.
Post by: Æthelwulf on 29/04/2012 06:48:35
http://arxiv.org/abs/0812.0240
I feel that confident with the famous George Ellis, this is all the references I need. Now, if time is not a river which extends from our past to future, then time cannot be linear. Besides, time is far from linear when you think about geometrical consequences of GR.
A river always flows downhill but not always at the same rate.
If by linear you mean as in a straight line with equal divisions then from a local time frame, time is always linear. Observed from any other non-local frame then time is seldom linear unless that frame is co moving.
A river is just an example... the old saying ''the river of time'' .... means it flows linearly from point to another, which as George Ellis clearly points out, it doesn't.
For locality we surely mean observer. And I'd agree, take the human observer who is aware of their surroundings. Their perception is strictly local with time and their experience of it --- but our experience of time arises because of a gene regulation inside our heads, the so-called, suprachiasmatic nucleus.
Beleiving for a moment that time exists objectively (outside the human perception) time is then part of the understanding of the manifold which requires a non-linear geometry. That would be most important, not the perception of it.
Post by: Geezer on 29/04/2012 06:52:52
AW,
You have been warned repeatedly that you may not patronize other members.
Please do not do that again. I think you are very familiar with what will happen if you do.
Can I just say for the record in case Geezer does find a reason to banish me, is that the the partonization was supposed to be in this line:
''If you are scared to use the word, you are not really agreeing with science.''
I did not however imply he was. I said ''if''. I know plenty of people in science who would say the same thing about anyone. I wouldn't dodge a question by saying ''maybe'' to a simple question like what is the spin of a fermion, is it a 1/2 spin? I wouldn't go, ''maybe''... I would say ''true''. If I said ''maybe'' it would mean to be taken that I have reservations on my answer, that I perhaps don't entirely agree with what science has to say.
Nice try, but if you had said you were sorry to the other members, you might have been saved. Instead you have earned a one week vacation to think about it.
Post by: Pmb on 29/04/2012 07:40:09
Also the question you referred to above is not a poor question. So if you answer the question already posed and if you can figure out why the question I just referred to was not a poor one then I'll finish responding to your comments.
Post by: MikeS on 29/04/2012 09:57:49
Quote from: Æthelwulf link=topic=43769.msg387100#msg387100
[i
[i
For locality we surely mean observer. And I'd agree, take the human observer who is aware of their surroundings. Their perception is strictly local with time and their experience of it --- but our experience of time arises because of a gene regulation inside our heads, the so-called, suprachiasmatic nucleus.[/i]
Beleiving for a moment that time exists objectively (outside the human perception) time is then part of the understanding of the manifold which requires a non-linear geometry. That would be most important, not the perception of it.
No it doesn't, that just synchronizes our body's circadian rhythms or body clock with the Earths clock.
Post by: yor_on on 02/05/2012 10:50:43
The very best math, to me, is the type that draws a new conclusion, and then also suggest some way to test that prediction.