Sharing with you good ways to Setup the Epson Printer ET2550 for good and easy printing of the documents.I need help with mine. It will only print "I am banned".
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Again, you seem to be searching for loopholes rather than focusing on the fundamental reasons why we choose to divert the trolley on a paper philosophy test but not in practice. I think there is a reason, but the best way to to see it is to consider the most favorable case, and wonder why it is still rejected. You seem to be looking for the less favorable cases, which is looking in the wrong direction.Quote from: HalcIt is considered (rightly so) unethical to harvest a healthy condemned criminal in order to save the lives of all these innocents in need. Now why is that?I have some possible reason to think about.
- Perhaps the crime isn't considered severe enough for death penalty."Condemned criminal" means it is severe enough. The death sentence has been made.
- Fear of revenge from the victim's relatives. There's always non-zero chance the secret will be revealed.There's a secret involved? I was suggesting this be above board. Not sure who the victim is here, the criminal or the victims of whatever crimes he committed. If the former, he's already got the death penalty and his relatives already know it. Changing the sentence to 'death by disassembly' shouldn't be significantly different from their POV than say death by lethal injection (which renders the organs unusable for transplants).
- Hope that there might be better options without sacrificing anyone, such as technological advancement.People in need of transplants often have short life expectancy, certainly shorter than advancement of technology. OK, they've made I think a few mechanical hearts, and the world is covered with mechanical kidneys (not implantable ones though). A dialysis machine does not fit in a torso. No mechanical livers. It's transplant or die. Not sure what other organs are life-saving. There are eye transplants, but that just restores sight, not life.
- The lost of those five lives are not that big deal. Life can still go on as usual.With that reasoning, murder shouldn't even be illegal.
Millions of lives had died due to accident, natural disasters, epidemic, famine, etc. without anyone getting their hands dirty of homicide.Ah, there's the standard. Because putting the trolley on the track with one is an act of homicide (involves the dirtying of someone's hands), but the non-act of not saving 5 (or 4) people who could be saved is not similarly labeled a homicide. Negligent homicide is effectively death caused by failing to take action, so letting the trolley go straight is still homicide.
In fact, I think it has never been done. But I'm asking why not, since it actually works better than the 'accidental' version they use now.Quote from: HalcThere is another solution: You have these 5 people each in need of a different organ from the one healthy person. So they draw lots and the loser gives his organs to the other 4. That's like one of the 5 trolley victims getting to be the hero by throwing the other 4 off the tracks before the trolley hits and kills him. Win win, and yet even this isn't done in practice.In practice, that is a very rare circumstance.
The cost/resource required could be high, especially if . Who will pay the operation?Same person who pays when there is a donor found. It costs this money in both circumstances. High cost of the procedure actually is an incentive to do it. The hospitals make plenty of money over these sorts of things, so you'd think the solution I proposed would be found more attractive.
The uncertainty of cost and benefit would make surgeons avert risks by simply doing nothing and noone would blame them.Surgeons always take risks, and sometimes people blame them. They say to watch out for surgeons who have too low of a failure rate for a risky procedure because either they cook the books or they are too incompetent to take on the higher risk patients. But people very much do blame surgeons who refuse to save lives when it is within their capability.
I think it's about linear motion, which has straight line trajectory.OK, so assuming the question is "Can a pure translation exist in the Universe?", I'd have to say that a geodesic is a straight line in a curved space. If that is an example of a pure translation, then any inertial non-rotating object meets this criteria, but if not, then nothing meets it because space isn't flat at a medium scale.
In the case of surgeon version of trolley problem, I think many people would make following assumptions that make them reluctant to make the sacrifice:Foot was correct in noticing that people don't really hold to the beliefs they claim. A hypothetical situation (trolley) yields a different answer than a real one (such as the surgery policy described actually being implemented as policy).
- there is some non-zero chance that the surgery would fail.
- the five patients' conditions are somehow the consequence of their own fault, such as not living a healthy life, thus make them deserve their failing organs.
- on the other hand, the healthy person to be sacrificed is given credit for living a healthy life.
- many people would likely see the situation in that healthy person's perspective.
Once we can get over this we can then proceed to a worthwhile discussion.Thanks for getting on with it. I've not found the time to respond properly to your lastest reply to me. Our discussion seems to be a difference in coordinate systems and I don't think we fundamentally disagree, and the points should not detract from your proceeding.
I think that I will express the main points what I am trying to describe in a different way
Now we are coming to the nub of the matter. You claim that the acceleration due to a rocket is “different” from the acceleration due to gravity. How could this be?It is different. Einstein considered gravity to be a curvature in the fabric of spacetime, and hence objects in freefall actually trace straight (geodesic) lines in their non-euclidean spacetime. Thus freefall is equivalent to being inertial outside the gravitational field. One just floats around and cannot tell which of the two situations one is in.
When an object is experiencing acceleration it doesn’t matter what kind of force is giving rise to that acceleration or what machine is responsible for it. If an acceleration is present it should have some effect on the spaceship and on its passengers also.Agree.
In the space station the astronauts are under the influence of a constant acceleration of around 8.4m/s2 why should you claim that this does not affect the astronauts?Einstein would claim they're not accelerating, but tracing a straight worldline. Only in a non-local coordinate system (that of Earth instead of the space station) is the space station accelerating. This may be difficult to visualize if you cannot conceive of 4 dimensional coordinates, let alone non-euclidean 4 dimensional coordinates.
In effect what you are saying, namely that there is a difference in acceleration due to gravity and that due to a rocket engineYes, there is very much a difference, since there is a trivial local test to distinguish one from the other.
is a complete right about turn to what the equivalence principle states, namely that there is no difference between the force caused by gravitation and that caused by an acceleration.A misstatement of the principle. It equates acceleration by non-gravitational force (a rocket engine say) to force exerted by the floor under me preventing the natural trajectory (a straight line) that gravity would otherwise take me. There is a non-gravitational force in both cases.
In my example, in a space craft far from anywhere else, the passengers are weightless, they are free falling around space, so the application of an acceleration would have no effect on them. As long as they are weightless, acceleration should not affect them.They would not be weightless if the spaceship was accelerating like that.
Or can you claim that these astronauts have weight?Yes of course they would. They could stand on a bathroom scale (a weight scale, not a mass scale) and it would read their weight. A weight scale measures force. A mass (balance) scale measures mass, a very different thing.
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How is it that there are rising sea levels impacting some island nations such as the Maldives and Kiribati, yet 1000 kilometres in any direction there is no discernible sea level change at all?"I've not seen any data on this. Sea level has risen about 1/6 meter in the 20th century, everywhere. These nations are at risk from a ~2 meter sea level rise (barring curbing of emissions) predicted for the 21st century since they've no high ground to which they can retreat. Netherlands is already below sea level, but they can only build their walls so high.
When I say event horizon I mean the Schwarzschild radius for a simple isolated non rotating black hole. That is the point at which no further communication to a distant observer is possible. This is more complex in the Kerr or rotating caseI mean that as well. Computation of the event horizon is more complicated given charge and rotation and such, but in the end the concept is the same. If the gravity at the horizon is 1550g's, then communication is possible by an object which has finite force enough to accelerate it at 2000 g's, and it thus isn't an event horizon. Emphasis on 'possible' above.
Kind of over my head. I know the firewall as one possible solution to a unitarity paradox. I'm only a novice at quantum field theory, so I won't be much use in the discussions. I'm speaking about the geometry of the black hole and nature of spacetime for hypothetical events enclosed by the event horizon.Quote from: Halcsince I don't understand the meaning of a frame of reference of something at a singularityIt appears you are talking about what happens near a theoretical "singularity" my arguments are essentially that this never happens. What prevents it from happening. In the first simple arguments it is just that a stasis can be reached via the energy outflow caused by the increasing gravity gradient at the "surface" (hawking radiation) overcomes the energy created by any further contraction towards the singularity. I tend to equate this with what other writers have called the quantum firewall.
In the rotation case, it is not the speed, but the acceleration that kills a person.Quote from: OriginAny speed won't hurt a person.True in translation, not in rotation like a circular path. The links between the atoms are weak and don't like centrifugal forces.
Does a pure translation can exist in the Universe ?Cannot parse this. What do you mean by 'translation'?
Halc You are still thinking incorrectly. The reference you give from Wikipedia refers to what you would "see"and measure from a distant viewpoint as things vanished into the event horizon.It is not. I'm talking about proper acceleration. It being infinite means that no amount of acceleration will allow an object to escape a black hole once it's at the even horizon. No force can hold it in place. According to your finite figure, if it were the proper acceleration required, there is such a force, and the event horizon can be escaped utilizing said greater acceleration.
am not talking about that. What you see from a distance is not what is observed by the particles falling through a gravitational Field.A particle falling in any gravitational field 'observes' no proper acceleration at all, per the equivalence principle. If it did, it wouldn't be falling.
The viewpoint I am taking is what you would see and measure if you were travelling along with the particles and observing what is happening to other particles nearbyYes, the finite value you speak is that. It isn't proper acceleration. I actually am not familiar with the meaning of the formula referenced since I don't understand the meaning of a frame of reference of something at a singularity. Hawking can clarify.
let us now try to come to some points of agreement.Yes, that gets you the Schwarzschild radius according to the escape velocity formula, which isn't particularly an inverse square law.
I presume that you agree that the radial position of the black hole event horizon in a spherical gravitational field created by an isolated (point) mass is defined by the point where the escape velocity equals the velocity of light according to the inverse square law
Sorry Halc but you are most definitely wrong in your thinking.The calculator is computing something else. Wish there was a link explaining.
I have already given you the reference three times in this note. Look at it. It is a very well respected java tool. http://xaonon.dyndns.org/hawking/
In relativity, the Newtonian concept of acceleration turns out not to be clear cut. For a black hole, which must be treated relativistically, one cannot define a surface gravity as the acceleration experienced by a test body at the object's surface. This is because the acceleration of a test body at the event horizon of a black hole turns out to be infinite in relativity. Because of this, a renormalized value is used that corresponds to the Newtonian value in the non-relativistic limit. The value used is generally the local proper acceleration (which diverges at the event horizon) multiplied by the gravitational time dilation factor (which goes to zero at the event horizon). For the Schwarzschild case, this value is mathematically well behaved for all non-zero values of r and M.The bold is what I'm talking about (proper acceleration), but the K thing that is in your calculator is defining something else, I think this "surface gravity of a static killing horizon", a term that's new to me.
When one talks about the surface gravity of a black hole, one is defining a notion that behaves analogously to the Newtonian surface gravity, but is not the same thing. In fact, the surface gravity of a general black hole is not well defined. However, one can define the surface gravity for a black hole whose event horizon is a Killing horizon.
Question:The latter equation I've seen expressed as the "proper acceleration of an object at time t relative to an observer in free fall, who is momentarily at rest w.r.to the object (being held at the horizon) at time t.
"... about the actual force (in Newtons) that an object with mass m would receive from a Black Hole with Schwarzschild radius if the object was on the Event Horizon"
"Hi Peterix, your question has been answered here. – John Rennie Apr 20 '14 at 8:05
Where, I can't find it? Anyway is F=mc4/4GM right? – Peterix Apr 20 '14 at 9:17
No, it's F=ma=GMmr/rē 1/(√(1-2GM/cēr)) – John Rennie Apr 20 '14 at 9:25"
The event horizon is at the point where the escape velocity is equal to the velocity of light.This makes it sound like things could move from inside to outside, but lacking escape velocity, they would eventually fall in. If true, this would violate the actual definition of an event horizon which is any boundary where events on one side can never have causal effect on events on the other.
Gravitational acceleration is not directly related to escape velocityA ship can escape Earth without ever reaching escape velocity. It just needs continuous acceleration, not even as much acceleration as the local gravity field. OK, it obviously eventually exceeds escape velocity as the escape velocity drops to less than the slow ship speed. So I agree that escape velocity has little to do with it.
Coming to your spaceship analogyThis depends heavily on how one defines efficiency, but I agree. They have Ion engines that do pretty much this, but they totally lack power. Efficiency isn't going to get you the 1550g you suggest. You need power, however inefficient. A railgun is perhaps up to the task. Not trying to get an object to escape the gravity well. Just trying to move it one meter from inside to outside. That shouldn't be possible even in principle (as it would be shooting something into the past) but if there is a mere 1550g gravity there, that is easily exceeded.
The most efficient propulsion system possible is that created by converting mass directly into energy of acceleration
Can I stress again that What I am talking about is what based on our knowledge of physics and relativity will happen in the early stages of the collapse inside the event horizonAgain, there are differing opinions on this. The no-interior one says there is no inside in which anything can happen.
To help illustrate this let me consider an isolated large black hole with a mass of around 10E9 solar masses the sort of thing that exists at the centre of many large galaxies but without the complications of a lot of other material nearby orbiting it at high speeds I will use the results from the website http://xaonon.dyndns.org/hawking/ to illustrate what it event horizon looks like.Acceleration to hold position at any black hole event horizon is infinite, not 1550. Not sure where you're getting that figure. If it wasn't infinite, then a ship with enough power to pull 2000 g's would be able to get out, and it wouldn't be an event horizon.
Its radius is 19.75 AU or about 3E9 KM Very similar to the orbit of Uranus
Its surface gravity is around 1550 earth gravities. Compare this with the surface gravity of a white dwarf star of 350,000 gravities. Physical laws are not distorted under these conditions.
The gravity gradient at the surface is only about 1E-9 Less than that on the earthAgain, not sure of the figure, but agree that the gravity gradient (tidal stress) on a large black hole is definitely far less than that of a little one.
It is quite clear that a theoretical space ship could cross this without any stress problemsIf it crosses at all, yes. But inside, 'towards the central singularity' isn't even a spatial dimension, so gravity force isn't even meaningful in that dimension, similar to how I cannot be pulled into the past by a sufficiently large mass that was here yesterday. That the critical part that must be addressed when considering the conditions of material that is posited to be inside.
Thank you all for your replies now to get down to the answers which I will take in chronological orderSo just explain how it could work. I don't mind the bias, but I mind the dismissing of the prevailing views by calling them "philosophically unattractive and stilted". The seeming fine tuning in fact attracts much attention from the 'creator' stance and is pushed as significant evidence for the stance. If you lack the space to take down the 'creator' view, then fine, but what I protest is the waving it away with reasons that don't hold water.
Halc. 12:25 15 nov
Clearly my title "Is an Evolutionary Cosmology possible?" declares my bias. I am trying to explain how I believe that an evolutionary cosmology could work within the bounds of current thinking and cannot expand all the arguments in this restricted format.
In the same way the black hole that internally created a universe as large and complex as ours in a different set of dimensions from ours will fade out and vanish in time.This view isn't all that different from the fractal eternal inflation theory that has each 'bubble' being birthed from some parent universe. The differences are that it isn't necessarily via black holes, and more importantly, no mention of a selection process that results in the tuning (as opposed to the more unlikely randomness) that we see.
Read further and think. Consider the physical evolution of particles atoms and stars through time which we understand quite well and use the analogy to consider ow physical laws might evolve. physical evolution in a cooling universe favours things that last longest in time. our laws settle out forma an infinite dimensional potential the way they do because they tend to favour the things that last longest in a metastable state.Black holes will indeed eventually be predominant, perhaps even over burnt out suns and rocks and such, but a universe in that state is also less likely to be observed.
Thermodynamics is not violated by my proposals and the energy (and mass!) created by the collapse of the matter inside the event horizon cannot be observed outside.We can compute them using the laws that we know, and I was suggesting you've made an error in doing so. The details were in reply 5, but I was waiting for a reply before diving into that.
Now a couple of general notes to thinkers on this subjectDon't you need to posit this? How is evolution to take place if the laws are identical inside as they were outside?
There is no reason to believe that physical laws change abruptly as an event horizon is lost.
What we see of material entering the event horizon is irrelevant what happens is what the individual leptons and quarks "experience" as they interact furiously a vast number of times in their relatively long passage towards the theoretical "singularity".Is it furious? We're supposedly in a parent black hole ourselves and I don't see this furious interaction. I don't see a theoretical singularity which is drawing everything in. Quite the opposite.
I pretty much dropped out of the conversation after pointing out a substantial list of claims contradicting empirical evidence, such as Pluto not having moons for instance.Quote from: HalcIt's just a force of gravity, one mass acting on another, each accelerating the other.Unfortunately, you did not understand my theory. I wasn't commenting on your theory. I was replying to Kryptid.
What would its properties be?This is a begging description. Black holes are a premise, and here we are stating that its properties would be much like that of a black hole. Fine and dandy, but it doesn't justify the text below that congratulates itself for finding something that meets this requirement.
It would have to be where part of the universe is cut off from the rest of the originating universe(s) by some process and then continues on with its own existence independently leaving only a shadow of its creation. Ideally it should also be seeded in some way with elements of the originating universe.
The big question is how can such a small object lead to a big universe?. The simple answer is that the process of collapse to a singularity under an inverse square law not only results in an infinite energy density it also releases an infinite quantity of energy!It violates thermodynamic law to say this. Infinite density at a singularity is not unexpected, but it isn't infinite energy. The energy is limited to the mass of the black hole, say a large star. Gravitational potential energy is negative, so there is no net gain of energy of the system.
This is simply provable by considering the energy released by a thin massive spherical shell of matter collapsing under the gravity of the mass inside the shell that is also collapsing towards a theoretical singularity.I think the proponents of this idea do suggest that matter does make its way into the interior and not get stuck at the event horizon, but this does lead to some paradoxes which must be resolved. In particular, any event within a black hole is in the future light cone of any event just outside of it in our spacetime. That means anything in there takes indefinite time (our frame) to do so, and since the black hole has a finite lifespan (it will evaporate via Hawking radiation in some finite time), the black hole will be gone before any matter can make its way inside. The black hole is gone before anything inside 'happens'. This needs to be resolved.
To get round this problem there is a tendency to think that there must be a vast number of isolated bubble universes existing in a Multiverse. Alternatively it leaves open the possibility that there is some sort of sentient creator of universes. Both of these approaches are very philosophically unattractive and stiltedHave not gone through it all, but this statement seems an open declaration of biases. No statement is made as to why either of these two alternatives should be discarded other than your personal distaste for them, and in fact, among those who hold any opinion on the subject, these two alternatives probably represent the vast majority of the backing, which makes them in fact quite attractive.
You didn't seem to give a distinction. You pointed to two posts both of which only used the word as 'infinity/eternity', indicating you mean the same thing by the words, not distinct concepts.Quote from: HalcSo why not just use the word 'infinity' when you mean that?Because colloquially there is a distinction which, seemingly, I am not alone in recognising.
I mean you've said it more than once.Quote from: HalcOK, this just reiterates what it isn't: a length of time.Let’s find the reiteration.
If the forces of nature are holding the material of the galaxies together, so they are not expanding with empty space, the galaxies would be stuck in an ancient nearly permanent space-time reference.No particular force holds the largest structures to each other since they are balanced in every direction. If the galaxies were distributed evenly (they're not), none of them would have a net force due to gravity and they'd all move away from each other due to expansion, the only effect left.
If I was to travel to the next galaxy, I would first enter an expanding space-time reference. As I approach the new galaxy, thanks to matter holding firm, I would then enter an older fixed reference, much closer to my original home.Sorry, you're on your own with this idea. I still move at so many meters per second relative to any object I choose, no matter where in space I am.
That being said, the collective red shift data of the universe actually says the universe expanded fastest near the beginningNot counting the inflation epoch (which cannot be seen), expansion is currently accelerating and thus was slower in the distant past.