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I have been thinking about that well known paradox about time travel, the one where you go back in time and shoot your parents and then you could not have been born and if you had not been born you could not have gone back in time and shot your parents....!?!?Would this answer: If I go back in time and CHANGE the past, then it is NO LONGER THE PAST. The past becomes the future. I think of the analogy of the expanding universe.. it can go both ways, as it were, from this point... it could shrink and go right back to the big bang and start all over again, or it could go on expanding. Maybe time is the same, so the future is not always what is AHEAD of you, it could also be BEHIND you.. so the future would just be the direction you are going in, the direction of change.this may be an old idea. I don't know. Maybe there is a flaw!Bitistoll
Here you go, if you go back in time, you could meet your parents and kill your parents, they however would not be your actual parents, they would be very similar, the reason for this is that by going back in time you would create a parallel universe.
QuoteHere you go, if you go back in time, you could meet your parents and kill your parents, they however would not be your actual parents, they would be very similar, the reason for this is that by going back in time you would create a parallel universe.The problem with this theory is that the number of 'parallel universes' that are created just gets bigger and bigger. Every single choice that is made can generate two or more.Does all this involve the transfer of energy? What about other physical laws; how are they affected?Or is the 'universe' just the one you, personally, experiencing? Do I get one too? How many am I allowed?The parallel universe idea sounds too much like a cop out because its exponents don't seem to see it through to any 'logical' conclusion.
The problem with this theory is that the number of 'parallel universes' that are created just gets bigger and bigger. Every single choice that is made can generate two or more.
Does all this involve the transfer of energy? What about other physical laws; how are they affected?
The 'killing your father' scenario forbids time travel in those circumstances. However, you could consider the possibility of returning to your past self providing information on how to build a time machine. Your early self uses this information and builds such a machine, taking some years, of course. You then decide to test the machine and find yourself in a room with your past self and provide information . . . . . and so on. This would constitute a 'permitted' loop in time. This is sustainable if you ignore freewill and randomness and you can't do that.The more separated (approaching zero 'causal connection') the time traveler and the place he visits , the more possible this scenario becomes. As long as the position of your time travel destination is far enough from your starting point (time shift times speed of light) then there would be no connection because no information could get back and modify the situation so that the time travel is aborted.This could imply that the maximum time you could travel backwards would be limited by the distance you travel; the bigger distance, the more your possible time shift.
I personally dont believe that randomness exists. if you get a random number from a computer, than it's corrupted data, and you end up with a blue screen. such a delicate system as our universe would be completely wiped out with the existance of random.
about the distance vs. time travel concept, could you not go around that by travelling half the distance you would need to get to the desired time, and then doubling back and going back in time the rest of the way, ending up at the same place?
But if you acknowledge the existence of paradoxes in principle, they could be occurring all over the place.
Surely the rules aren't just there on the off chance that someone will invent a time machine. After all, a time machine must be based on some natural phenomenon, as yet not discovered by us.You'll have to do better than just to suggest a brand new phenomenon with no good reason or without looking at the possible consequences. That is unless this is just a fantasy website.
Quote from: sophiecentaur on 19/04/2008 17:43:02The problem with this theory is that the number of 'parallel universes' that are created just gets bigger and bigger. Every single choice that is made can generate two or more.Agreed, but it does give the opportunity for the appearance of time travel without the reality of it (i.e. you can enter a universe that looks like our universe did 50 years ago, without actually having a causal impact on our present universe).Unless we can look ahead into the parallel universe before we jump there, we could jump into absolutely any arbitrary environment without any control whatsoever - an environment that is more likely than not to be highly hostile to our presence there.
Quote from: science_guy on 20/04/2008 03:10:49I personally dont believe that randomness exists. if you get a random number from a computer, than it's corrupted data, and you end up with a blue screen. such a delicate system as our universe would be completely wiped out with the existance of random.There are many computer functions that require randomness in their operation: encryption algorithm's; Monte Carlo statistical method; and many others.As for randomness in the physical world - this is a debate that has long gone on in discussing quantum physics, but the current consensus is that events in quantum physics can be random.
Someone above said that they do not believe that randomness can exist in the universe because, like a computer, the universe is delicate.Do you really think the universe is as delicate as a computer? I mean, what about self-regulating systems, such as our world? Computers do not have the ability, except in rather trivial ways, of mending or correcting themselves. We do, we recover from many seriour illnesses, and our environment is also self-regulating, in that, eg, if we deplete the oxygen them microbes in the ocean respond by creating more, but if we put too much oxygen into the atmosphere, then the microbes of another kind flourish and work to counter the excess oxygen. So we are surrounded, at least in our world, by evidence that the universe is CAPABLE of being self-regulating, and of recovering from mistakes etc. If it is capable of doing so on the small scale, is there reason to suppose the bigger universe might not also be self-regulating?
There is a huge difference between random (as in quantum mechanics) and pseudo-random, as in computing.
Quote from: science_guy on 20/04/2008 03:10:49I personally dont believe that randomness exists. if you get a random number from a computer, than it's corrupted data, and you end up with a blue screen. such a delicate system as our universe would be completely wiped out with the existance of random.There are many computer functions that require randomness in their operation: encryption algorithm's; Monte Carlo statistical method; and many others.There are different types and quality of random numbers, some being dependent on physically random events, and some, which are merely pseudo random numbers, depend purely on calculation. Pseudo random numbers are not considered adequate for many of the uses to which random numbers are put to in computing, although they do have their advantages where you want repeatability in your results (clearly, when generating encryption keys, one thing you do not desire is repeatability, otherwise two people are likely to get the same encryption key).As for randomness in the physical world - this is a debate that has long gone on in discussing quantum physics, but the current consensus is that events in quantum physics can be random.
everything in the universe comes from something else, cause generates effect. you cannot have an effect without a cause, which is basically what random is.
being a programmer, I know that in a computer program, the computer only accepts code that it expects, or what the programmer wrote to it.
a "random" function is selected from a usually large collection of choices, chosen based upon the current value of a constant, a common one being the current millisecond.
In computing, a hardware random number generator is an apparatus that generates random numbers from a physical process. Such devices are often based on microscopic phenomena such as thermal noise or the photoelectric effect or other quantum phenomena. These processes are, in theory, completely unpredictable, and the theory's assertions of unpredictability are subject to experimental test. A quantum-based hardware random number generator typically contains an amplifier to bring the output of the physical process into the macroscopic realm, and a transducer to convert the output into a digital signal.Random number generators can also be built from macroscopic phenomena, such as playing cards, dice, and the roulette wheel. The presence of unpredictability in these phenomena can be justified by the theory of unstable dynamical systems and chaos theory. These theories suggest that even though macroscopic phenomena are deterministic in theory under Newtonian mechanics, real-world systems evolve in ways that cannot be predicted in practice because one would need to know the micro-details of initial conditions and subsequent manipulation or change.There are two fundamental sources of practical quantum mechanical physical randomness: quantum mechanics at the atomic or sub-atomic level and thermal noise (some of which is quantum mechanical in origin). Quantum mechanics predicts that certain physical phenomena, such as the nuclear decay of atoms, are fundamentally random and cannot, in principle, be predicted. (For a discussion of empirical verification of quantum unpredictability, see Bell test experiments.) And, because we live at a finite, non-zero temperature, every system has some random variation in its state; for instance, molecules of air are constantly bouncing off each other in a random way. (See statistical mechanics.) This randomness is a quantum phenomenon as well. (See phonon.)Because the outcome of quantum-mechanical events cannot in principle be predicted, they are the 'gold standard' for random number generation. Some quantum phenomena used for random number generation include:Shot noise, a quantum mechanical noise source in electronic circuits. A simple example is a lamp shining on a photodiode. Due to the uncertainty principle, arriving photons create noise in the circuit. Collecting the noise for use poses some problems, but this is an especially simple random noise source.A nuclear decay radiation source (as, for instance, from some kinds of commercial smoke detectors), detected by a Geiger counter attached to a PC.Photons travelling through a semi-transparent mirror, as in the commercial product, Quantis from id Quantique. The mutually exclusive events (reflection — transmission) are detected and associated to "0" or "1" bit values respectively.Thermal phenomena are easier to detect. They are (somewhat) vulnerable to attack by lowering the temperature of the system, though most systems will stop operating at temperatures (e.g., ~150 K) low enough to reduce noise by a factor of two. Some of the thermal phenomena used include:Thermal noise from a resistor, amplified to provide a random voltage source.Avalanche noise generated from an avalanche diode, or Zener breakdown noise from a reverse-biased zener diode.Atmospheric noise, detected by a radio receiver attached to a PC (though much of it, such as lightning noise, is not properly thermal noise, but most likely a chaotic phenomenon).Another variable physical phenomenon that is easy to measure is clock drift.In the absence of quantum effects or thermal noise, other phenomena that tend to be random, although in ways not easily characterized by laws of physics, can be used. When several such sources are combined carefully (as in, for example, the Yarrow algorithm or Fortuna CSPRNGs), enough entropy can be collected for the creation of cryptographic keys and nonces, though generally at restricted rates. The advantage is that this approach needs, in principle, no special hardware. The disadvantage is that a sufficiently knowledgable attacker can surreptitiously modify the software or its inputs, thus reducing the randomness of the output, perhaps substantially. The primary source of randomness typically used in such approaches is the precise timing of the interrupts caused by mechanical input/output devices, such as keyboards and disk drives, various system information counters, etc.This last approach must be implemented carefully and may be subject to attack if it is not. For instance, the generator built into the Linux kernel, which combines several such sources, may be vulnerable to an attack . The random number generator used for cryptographic purposes in an early version of the Netscape browser was certainly vulnerable (and was promptly changed).One approach in using physical randomness is to convert a noise source into a random bit sequence in a separate device that is then connected to the computer through an I/O port. The acquired noise signal is amplified, filtered, and then run through a high-speed voltage comparator to produce a logic signal that alternates states at random intervals. At least in part, the randomness produced depends on the specific details of the 'separate device'. Care must also always be taken when amplifying low-level noise to keep out spurious signals, such as power line hum and unwanted broadcast transmissions, and to avoid adding bias during acquisition and amplification. In some simple designs, the fluctuating logic value is converted to an RS-232 type signal and presented to a computer's serial port. Software then sees this series of logic values as bursts of "line noise" characters on an I/O port. More sophisticated systems may format the bit values before passing them into a computer.Another approach is to feed an analog noise signal to an analog to digital converter, such as the audio input port built into most personal computers. The digitized signal may then be processed further in software to remove bias. However, digitization is itself often a source of bias, sometimes subtle, so this approach requires considerable caution and care.Some have suggested using digital cameras, such as webcams, to photograph chaotic macroscopic phenomena. A group at Silicon Graphics imaged Lava lamps to generate random numbers. U.S. Patent 5,732,138 One problem was determining whether the chaotic shapes generated were actually random -- the team decided that they are in properly operating Lava lamps. Other chaotic scenes could be employed, such as the motion of streamers in a fan air stream or, probably, bubbles in a fish tank (fish optional). The digitized image will generally contain additional noise, perhaps not very random, resulting from the video to digital conversion process. A higher quality device might use two sources and eliminate signals that are common to both— depending on the sources and their physical locations, this reduces or eliminates interference from outside electric and magnetic fields. This is often recommended for gambling devices, to reduce cheating by requiring attackers to exploit bias in several "random bit" streams.The Commodore C64 provided a hardware random number generator, included in its soundchip, the MOS Technology SID 6581. Random bytes are fetchable by a read on the correct memory address on the 6581.
That is a statement of belief, but can you prove it to be true?There are two different issues here - one is an unseen (and unseeable) cause (such as a cause that exists beyond an event horizon), and an event that genuinely exists without any possible correlating cause.Clearly, classical science requires absolute causality, and it would still be a far more elegant solution to believe we could still retain the Newtonian totally deterministic view of the universe, the present theories seem to contradict that. Many people, myself included, are not comfortable with that restricted determinism, but simply stating it is wrong does not provide a better alternative.
The computer will indeed only accept code that is written for it, but that does not mean that the computer will always perform that code in the same way (although they are designed, as far as practical, to do just that). Things like task scheduling, external interrupts, and endless other factors (aside from hardware errors) can mean the same code can have a certain randomness in its operation. In this case, most of that randomness relates to causes that occur beyond the event horizon of the program, but nonetheless from the perspective of the program, they are random events.
Adequate for fairly simple requirements, but anyone looking to seed an encryption algorithm will sue you through the courts if all you left him with was a random number generator based on a millisecond timer function.Luckily, modern operating systems (both Windows and Linux) provide operating system functions that mix various sources of randomness to provide something better than mere millisecond clock timers.Nonetheless, the best random number generators are generally specialised hardware devices that are based on quantum noise effects.
most effects have a conceivable cause, like gravity. But my viewpoint seems to weaken here when you come across an event that has no conceivable cause. It could be explained that, due to the pecularities of quantum physics and miniature time dimentions, that such effects do indeed have causes, they just have not occured as of yet.
while such randomness does occur in coding, it is caused by those things you just listed, therefore is not completely random. these causes, as you said, are beyond the perception of the program. such random events, however, are usually known, and the program will act accordingly as if were input.
again, the systems are not truly random, since the effect of random is based on the cause of quantum noise effects. as I stated earlier in the post, on a quantum level, it is possible that causes are on a differing timeline than ours, generating the perception of an event that has no cause.
The statistics of these 'truly' random events (e.g. thermal noise) seems to imply that randomness is a 'real' concept. The autocorrelation function of good healthy white noise is pretty much an impulse, however carefully you measure it. The mechanism which is producing this, what you might call 'quasi randomness' must be pretty good - in my opinion it is easier to think that it is actually randomness and not something that just looks like randomness.
Quote from: sophiecentaur on 21/04/2008 17:17:57The statistics of these 'truly' random events (e.g. thermal noise) seems to imply that randomness is a 'real' concept. The autocorrelation function of good healthy white noise is pretty much an impulse, however carefully you measure it. The mechanism which is producing this, what you might call 'quasi randomness' must be pretty good - in my opinion it is easier to think that it is actually randomness and not something that just looks like randomness.To play devils advocate, the statistical characteristics of the output of a good encryption algorithm, or an idealised compression algorithm, would both look like random noise unless you knew to decryption/uncompression algorithm to recover the original data.
Quote from: science_guy on 21/04/2008 05:41:51most effects have a conceivable cause, like gravity. But my viewpoint seems to weaken here when you come across an event that has no conceivable cause. It could be explained that, due to the pecularities of quantum physics and miniature time dimentions, that such effects do indeed have causes, they just have not occured as of yet.What do you mean by the term 'cause'?Being practical, gravity is not so much a 'cause' (for we cannot actually know true causes, if they exist), but a set of equations that model actions, and those equations can be used to predict future actions.It is conceivable that the true causes of motion have noting to do with gravity, but the idea of gravity is sufficient to allow us to make predictions about motions of massive objects.So, the questions regarding quantum phenomena are as much about whether you believe they are predictable as whether they have a cause. If you cannot create a predictive model, then from our perspective, the actions are random, no matter whether there be hidden causes or not.Quote from: science_guy on 21/04/2008 05:41:51while such randomness does occur in coding, it is caused by those things you just listed, therefore is not completely random. these causes, as you said, are beyond the perception of the program. such random events, however, are usually known, and the program will act accordingly as if were input.Yes, but from the perspective of the program, it cannot maintain a predictive model of such events, and so such events are (from it's perspective) purely random.Looking back at the multiverse examples we discussed above, if entities are jumping from one universe to another within a multiverse, someone with an overview of all of the multiverse may well be able to determine a predictive model that encompasses the entire multiverse, but to someone who only has information from within a single universe, these jumps between universes will simply be percieved as unpredictable random events.Quote from: science_guy on 21/04/2008 05:41:51again, the systems are not truly random, since the effect of random is based on the cause of quantum noise effects. as I stated earlier in the post, on a quantum level, it is possible that causes are on a differing timeline than ours, generating the perception of an event that has no cause.But perception is all. If it quacks like a duck, etc. Science is about explaining and predicting perceived truths - it does not delve into the metaphysical or unperceived 'realities'.
are you saying im the devil? [!]
my argument is that, assuming we could know and perceive everything, than everything would have a perceivable cause.
as per my earlier argument, the effect of our orbit around the sun is from the cause of gravity.
my term for "cause" by the way, is something that generates an effect.
This sounds like something of a circular argument. You seem to be saying that if we could know the cause of everything then everything must have a cause. This is self evidently true, as is the converse argument, that if not everything has a cause, then we cannot possibly know the cause of everything.
I would suggest that this is convenient shorthand, but is not provably true.What we know is that the equations for gravity can be used to predict the orbit of our motion about the Sun, but we can never prove that this is, nor that it is not, the actual cause of our orbit around the Sun.
But cause and effect are merely perceptions. This is particularly demonstrably true because there are situations where relativity predicts that the apparent order of events may appear to be different for one observer than for another observer, and in that case, how can you determine cause and effect?