Spyman

Because it is clearly not consistent with this statement: To which I have been arguing against since this thread started.

In the whole thread you have claimed that it is physically impossible to be exactly at that point, while I have tried to no avail to explain for you that the actual position where the events are made are in the present. I think it is time that you reread the thread and then restate your position. Either you have altered you view while the discussion has proceeded or there is a growing pile of contradictions you need to sort out before it makes any sense to continue. I am sorry, I thought that question was for Iggy. I think the observer at point A both sees the image and feels the gravity from point C. But when the light and gravity was emitted from Paul at point C, the observer was there in the same present as your diagram from post #167 shows:

Yes, we agree, timetravel is not ruled out. What I have been trying to say is that it is not ruled in either, it is still an open question.

The correct formula for calculating the kinetic energy an asteroid hits Earth with is: [math]E_K=\frac{1}{2}mv^2[/math] Where m is the mass of the asteroid and v is the impact speed relative Earth. Regarding your miscalculation Newton is in kg*m/s^2 and you have used acceleration in km/s^2 so the kilo is unaccounted for in your answer.

I don't know that we have a positive scientific theory of time travel, all that we seem to have is a lack of conclusive evidence against it. Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space. Time travel could hypothetically involve moving backward in time to a moment earlier than the starting point, or forward to the future of that point without the need for the traveler to experience the intervening period (at least not at the normal rate). Any technological device – whether fictional or hypothetical – that would be used to achieve time travel is commonly known as a time machine. Although time travel has been a common plot device in science fiction since the late 19th century, and the theories of special and general relativity suggest methods for forms of one-way travel into the future via time dilation, it is currently unknown whether the laws of physics would allow time travel into the past. Such backward time travel would have the potential to introduce paradoxes related to causality, and a variety of hypotheses have been proposed to resolve them, as discussed in the sections Paradoxes and Rules of time travel below. http://en.wikipedia.org/wiki/Time_travel However, the theory of general relativity does suggest a scientific basis for the possibility of backwards time travel in certain unusual scenarios, although arguments from semiclassical gravity suggest that when quantum effects are incorporated into general relativity, these loopholes may be closed. These semiclassical arguments led Hawking to formulate the chronology protection conjecture, suggesting that the fundamental laws of nature prevent time travel, but physicists cannot come to a definite judgment on the issue without a theory of quantum gravity to join quantum mechanics and general relativity into a completely unified theory. http://en.wikipedia.org/wiki/Time_travel I only have little knowledge of relativity and know almost nothing about quantum mechanics, but from my understanding although they not specifically rule out the possibility of time travel, neither of them makes any claims of an assured possibility thereof either. The general theory of relativity extends the special theory to cover gravity, illustrating it in terms of curvature in spacetime caused by mass-energy and the flow of momentum. General relativity describes the universe under a system of field equations, and there exist solutions to these equations that permit what are called "closed time-like curves," and hence time travel into the past. The first of these was proposed by Kurt Gödel, a solution known as the Gödel metric, but his (and many others') example requires the universe to have physical characteristics that it does not appear to have. Whether general relativity forbids closed time-like curves for all realistic conditions is unknown. http://en.wikipedia.org/wiki/Time_travel Certain experiments carried out give the impression of reversed causality but are interpreted in a different way by the scientific community. For example, in the delayed choice quantum eraser experiment performed by Marlan Scully, pairs of entangled photons are divided into "signal photons" and "idler photons", with the signal photons emerging from one of two locations and their position later measured as in the double slit experiment, and depending on how the idler photon is measured, the experimenter can either learn which of the two locations the signal photon emerged from or "erase" that information. Even though the signal photons can be measured before the choice has been made about the idler photons, the choice seems to retroactively determine whether or not an interference pattern is observed when one correlates measurements of idler photons to the corresponding signal photons. However, since interference can only be observed after the idler photons are measured and they are correlated with the signal photons, there is no way for experimenters to tell what choice will be made in advance just by looking at the signal photons, and under most interpretations of quantum mechanics the results can be explained in a way that does not violate causality. http://en.wikipedia.org/wiki/Time_travel

Since both Iggy and I seem to understand each other perfectly well the odds are in favor of you being confused and not us. I thought I asked a very simple question: But you didn't seem to be able to explain it, so I ask again: What is the Black dot at point B representing?

AFAIK there is no theoretical evidence that we should be able to travel backwards in time.

That depends on what you are trying to do, it looks like you have miscalculated the needed force to make it stop in 1200 days by 1000 times...

It does matter because I mentioned another example to which you claimed would not wipe out the human species if it was fragmented and if you change the goalpost then we could end up talking about something completely different. I don't know why you want to change it but it is ok, carry on.

I accept 951 Gaspra with an estimated mass of 2.5e16 kg and a rocky density of 2.7 g/cm3 as an valid example.

It doesn't work that way, you started this thread and you are the one making the claims in the OP. If you want us to belive in your claims then it is up to you to provide the necessary evidence to convince us that you are correct. It is even stated in the Speculations Forum Rules that: "Speculations must be backed up by evidence or some sort of proof." You need to provide a rigorous mathematical analysis, showing exactly how all the energy gets dispersed and prove with a very high degree of margin for error that this energy will be of a substantial too low level to cause any significant harm to the biological system. And since your claim seems to go against the general regarded deadliness of fragmented asteroids, you also need to supply links and quotes of statements and studies by professional experts that agree with and supports your claim.

It would truly be the end of civilization as we know it, but large military facilities with supplies and equipment like the Cheyenne Mountain Directorate or something like the private Ark Two Shelter could protect small groups of humans that possibly could restart our civilization. However studies have showed that most people on the planet would have starved to death within the following year after the impact blast since it would be to cold for any outdoor food production and the Nuclear Winter could very well last for more than a decade. With reasonable pre warning we could build a lot of shelters and outfit them with food, tools to build large greenhouses and the needed seeds. But protecting these buildings would also be a real problem since large crowds of wandering marauders would tear them apart in their battle for survival. I think most people are likely more eager to pay for the threat to be deflected than for a few *others* to survive in a *luxuary* shelter. But for optimal protection of our existence we should both develop collision avoidance strategies and build several large shelters.

No, I am not, you are wriggling around again...

Then what is the black dot in your diagram representing? Because it is clearly not comoving in the red dots past light cone.

But you claim that there is only ONE comoving object and that this object is located at the past light cone for the observer. That is certainly not compatible with the notion of another duplicate of this same object comoving in the observer's present.

With your diagram in post #167 and your statement in post #125.

Are you sure? What an statement. I would say not in a past spacetime location. Yes, I am sure. What is troubling you with my statement?

A large rubber pile would be much harder to deflect and to do so safely. But I don't think we can say for certain what amounts and kinds of different boulders there are out there. Deep Impact is a NASA space probe launched on January 12, 2005. It was designed to study the composition of the comet interior of 9P/Tempel, by releasing an impactor into the comet. (...) Initial results were surprising as the material excavated by the impact contained more dust and less ice than had been expected. The only models of cometary structure astronomers could positively rule out were the very porous models which had comets as loose aggregates of material. In addition, the material was finer than expected; scientists compared it to talcum powder rather than sand. http://en.wikipedia.org/wiki/Deep_Impact_(spacecraft) Even if several kinds of mammals like rats survives and then evolves they would still not be humans. Numerous groups of organisms went extinct during the K-T event, most notably the non-avian dinosaurs. Non-avian dinosaur fossils are found only below the K–T boundary, indicating that they became extinct during the boundary event. A very small number of dinosaur fossils have been found above the K–T boundary, but they have been explained as reworked fossils, that is, fossils that have been eroded from their original locations then preserved in later sedimentary layers. Mosasaurs, plesiosaurs, pterosaurs and many species of plants and invertebrates also became extinct. Mammalian clades passed through the boundary with few extinctions, evolving and thriving well past the event. Rates of extinction and radiation varied across different clades of organisms. http://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event

But if you claim that there can only be one, you have to choose where that one is located in time, it can not both be comoving in the present and comoving in different pasts simultaneously, that is a large contradiction.

LOL You are wrong. Obviously we are talking about something able to cause a mass extincion in this context and not something actually able to destroy the planet. In other words you still believe that fragmenting the rock will help. You are of course free to keep your belief and put faith in your speculations. However facts and experts does not agree with you and since your evidence is lacking, I strongly suggest others to not trust you on this. Siddhartha's opinion doesn't have any weight here... So have you seen any dinosaurs lately? Experts seems to agree with me that large asteroids are a seriously threat. Meteorite impact Earth has collided with several asteroids in recent geological history. The Cretaceous-Tertiary asteroid, for example, is theorized to have caused the extinction of the dinosaurs 65 million years ago. If such an object struck Earth it could have a serious impact on civilization. It is even possible that humanity would be completely destroyed; for this to occur the asteroid would need to be at least 1 km (0.62 mi) in diameter, but probably between 3 and 10 km (2–6 miles). http://en.wikipedia.org/wiki/Risks_to_civilization,_humans_and_planet_Earth#Meteorite_impact

I am reading your posts thoroughly but the problem is that you keep changing your mind, wriggling around and avoiding to express yourself clearly. If you truly acknowledge conservation of energy and thinks that the fragments would heat the atmosphere to much then you must also agree with: "However bombing it with the sole purpose to break it up into smaller pieces will only help if it is to small to cause an catastrophic extinction level event, an Earth killer will release enough energy into the atmosphere to wipe us out even if all pieces are small enough to burn up before they reach the ground." I asked you if you had changed your mind to agree with what I said in post #16 and you answered "No" in post #17. You need to make your mind up. Will the rock with 10 km diameter and impact velocity of 60 km/s cause a mass extincion even if fragmented or not? Yeah sure - Why am I not surprised?

What happened with: This last diagram have the companion comoving in the present and not at the surface of the Past Light Cone.

Look questionposter this is getting tiresome, I never said that small pieces would not vaporize in the atmosphere. You are either completely missing the point or deliberately avoiding to address it. If you don't want to learn then I am not going to force feed you, this is my last try. Yes, the energy will get transferred to Earth differently. Yes, the crust of the Earth will remain fully intact. But the atmosphere will be warming up as HELL due to the following two facts I have tried to get you to understand: FACT: The amount of energy released by a single large collision or many small collisions is essentially the same, given the physics of kinetic and potential energy. Do you really not understand that all the smaller pieces will release the same amount of kinetic energy into the atmosphere of Earth? It doesn't matter what size the pieces have, they could be tiny, medium or large chunks but still deliver the same total energy. FACT: The total kinetic energy delivered on impact or from vaporising by a 10 km diameter rock coming at us with 60 km/s is ENORMOUS! Do you really not understand that this is much much more than the energy the Earth gets from a few seconds of sunlight? The fragments could together cause an tremendous explosion in the atmosphere that in total equals to 610 000 000 000 000 tons of TNT. (That is like 500 miljoooooon nuclear bombs or almost 25 000 times greater than all nuclear warheads in the world together.) Lets look at what you have claimed since you don't even seem to understand what you have said and I want evidence for: FACT: I said that breaking a rock large enough to cause mass extinction up into smaller pieces would not help. FACT: I gave an example of an rock with 10 km diameter and impact velocity of 60 km/s like Comet Shoemaker–Levy 9. FACT: You oppose that and claimed that fragmenting this rock would help and stop an mass extinction from occurring. Now can you provide provide evidence that a mass extinction can be prevented if the mentioned rock will get fragmented? I don't want to hear that you don't know or can't do and neither what you think, guess or suppose, PROVE IT! You can of course also admit that you were wrong and retract your claim, instead to be too stubborn to learn.

I am a little worried since you say you are a mother of two children and seems to want to perform your experiments in your home. A *generator* powerful enough to be able to manipulate brain waves is very likely going to be dangerously unhealthy to be close to. Please keep your two sons on a safe distance from your invention, young children are often more vulnerable when exposed to hazards.

If you mean reputation votes on posts there already is a thread for that here: Changeable Votes of Reputation For a short duration after voting