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Title: Time Post by robman_rob on Feb 21st, 2008, 11:28am Hi, I'm new to this forum. In general I like riddles, so I was very happy to stumble across this forum. I have a riddle that may tickle you funny. I did some basic searches and did not find anything like this riddle being asked already. How would you know if time went by twice as fast? |
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Title: Re: Time Post by towr on Feb 21st, 2008, 11:51am [hide]In the same way you'd notice the universe was half the size. not [/hide] |
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Title: Re: Time Post by JiNbOtAk on Feb 21st, 2008, 7:35pm Driving your mum to buy groceries for half an hour is far too long, driving your girlfriend back to her home for two hours is far too short. |
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Title: Re: Time Post by Grimbal on Feb 24th, 2008, 8:48am Anyway, time doesn't pass. Time stays. We pass. |
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Title: Re: Time Post by Three Hands on Feb 25th, 2008, 2:21pm Depends on your model of time. Equally, depends on if you consider time to exist in the first place... |
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Title: Re: Time Post by rmsgrey on Feb 25th, 2008, 4:27pm How are you defining the rate at which time passes? I regard time as passing at 1 second per second - anything else sounds logically problematic, at best... |
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Title: Re: Time Post by towr on Feb 26th, 2008, 1:05am on 02/25/08 at 16:27:27, rmsgrey wrote:
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Title: Re: Time Post by Grimbal on Feb 26th, 2008, 1:30am I don't see how we could. Just as we wouldn't notice if God made backups of the world and restored it from time to time to make up for His/Her mistakes. |
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Title: Re: Time Post by rmsgrey on Feb 26th, 2008, 11:39am But is that a question of time in the universe changing, or of the interface between "God-space" and the universe changing? |
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Title: Re: Time Post by towr on Feb 26th, 2008, 12:09pm on 02/26/08 at 11:39:24, rmsgrey wrote:
Now assuming the program has no access to the clockspeed itself, nor to external sources of temporal information, but only to changes of it's own data. Then how can it tell whether the clockspeed has changed? Even though it really is running twice as fast, it can't tell. As far as the program is concerned it's running one clock-cycle per clock-cycle, same as before; whereas for the programmer it's running twice as many clock-cycles per second. |
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Title: Re: Time Post by tiber13 on Feb 26th, 2008, 1:20pm ah, but your CPU would go twice as fast, like time and if time went twice as fast, that would be the new time, so ......... |
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Title: Re: Time Post by towr on Feb 26th, 2008, 1:51pm on 02/26/08 at 13:20:38, tiber13 wrote:
You realize that was an analogy, right? And not a suggestion that to determine whether your universe was sped up you should look at your computer's CPU.. |
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Title: Re: Time Post by Grimbal on Feb 27th, 2008, 5:43am Of course, if one day you measure the speed of light at 150'000 km/s, you might think something fishy is going on... Or is God above Relativity? ;) |
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Title: Re: Time Post by towr on Feb 27th, 2008, 6:02am on 02/27/08 at 05:43:58, Grimbal wrote:
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He's everywhere, so in particular above relativity ;) And changing such fundamental things as the rate of passage of time must inevitably have consequences for the fundamental "constants" in physics as well. |
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Title: Re: Time Post by BenVitale on Mar 4th, 2008, 1:27pm So, we can post physics questions !? If I take any two real clocks, synchronise them, and let them run, after some time, they will always disagree about what time it is. So which of them measures the real time? Is there such a thing as absolute time -- a time measured imperfectly by any actual clock? |
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Title: Re: Time Post by Sir Col on Mar 4th, 2008, 3:01pm On a superficial level we could use the time it takes for our planet to rotate once on its axis as the definition of twenty-four hours, but it is not constant. We could measure time based on dividing the time it takes for Earth to orbit the sun, but that is not constant. In reality there is no such thing as "real time", as nothing moves uniformly or with constant frequency; every system requires resynchronisation. Even if we had such a mechanism that counted units of time with perfect regularity, it would cease to be useful in our irregular universe. But the existence of such a device is a contradiction in terms... The very presence of matter, including the "clock" itself, causes the "currents" of space-time as it flows to disturb the behaviour of the system. The only way to have a perfect clock would be to have no matter, in which case you have no clock. |
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Title: Re: Time Post by onlyme722 on Mar 4th, 2008, 3:30pm Well I'm wondering if this is asking "if right now time were to suddenly start going twice as fast, how would we notice?" Any means of human devices to record time would be moot because they are still programmed mechanisms. I'm assuming that our world wouldn't suddenly seem as though it were in fast forward mode, but the question is posed in an obscure manner. Logically I would suggest that we would measure time as it was done before man had even dreamed of creating a clock. We measured time by the passing of the sun. The problem is when would we begin to notice this change? But it would happen somewhere along the line. The best would be a means of comparison. A man-made clock and a sun-dial. The man made clock would take 12 hours for the hour hand to make a full cycle, and the sundial would only be a 6 o'clock at that point. But once again, how would we know to look for this comparison? I'm guessing the answer is to be more clever than this, but it's a perfectly legitimate answer. |
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Title: Re: Time Post by Icarus on Mar 4th, 2008, 4:33pm The question is meaningless. "fast" is a reference to the rate of change of a quantity with respect to time. The rate of change of time with respect to time can only be 1. In order for time to run "faster", we need a different timescale to compare it to. Thus we can talk about time passing faster for someone standing still than for someone traveling at a high rate of speed, because we are comparing one time scale to the other. But in this question, there is no alternative time scale to which we may compare our own. Without such a comparison, "twice as fast" has no meaning. ----------------------------------------------- Concerning the measurement of time, I cannot completely agree with Sir Col. Just because there are limits to our ability to measure a value does not mean the value does not really exist. And it may even be possible to build a mechanism that exactly measures time (if certain ideas about time floating about now should prove to be true). Of course, such a device can only measure time in its own locality, effected by its own existence. But within that locality, its measurement would be perfect. Its existence is not a contradiction. |
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Title: Re: Time Post by BenVitale on Mar 4th, 2008, 5:17pm The existence of absolute time is hard to prove. But, then again, we don't have to be too concerned with it. We learn in physics how motion and time are interconnected. We cannot conceive motion without time. The simplest law of motion, which was invented by Galileo and Descartes, and formalised by Isaac Newton. If we start to believe in some absolute flow of time, then we will face a dilemma: Would time flow if there were nothing in the universe? If everything stopped, if nothing happened, would time continue? |
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Title: Re: Time Post by Icarus on Mar 4th, 2008, 6:05pm The existence of "absolute time" is not just hard to prove, it is impossible, like all other theoretical constructs. The best we can do is gather empirical evidence in support of the idea (and the empirical evidence in this case is extremely strong). But empirical evidence always falls short of actually proving that something must be true. You just may not have come across the exceptions yet. We cannot conceive of motion without time for the same reason we cannot conceive of 2 without 1. Motion is, by definition, change with respect to time. Without time, motion is not defined. If everything stopped in the universe, I would not care if time continued or not, as I would no longer exist. Whether time would stop under such a situation or not has no effect on the behavior of time and motion in the reality we see, so I fail to understand why this is any sort of dilemma. |
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Title: Re: Time Post by BenVitale on Mar 4th, 2008, 6:31pm I argue that it becomes a dilemma or paradox for those who choose to believe in some absolute flow of time. |
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Title: Re: Time Post by Icarus on Mar 4th, 2008, 6:39pm Why? I believe in such a flow (I think - I am not completely sure what you mean by this phrase), and I find nothing bothersome about it. |
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Title: Re: Time Post by BenVitale on Mar 4th, 2008, 9:46pm You believe in absolute time, and yet we cannot observe it. The physics of time/motion is an attractive point of view since it doesn't lead us to believe in some absolute flow of time that we cannot observe. My question to you is what could it mean to say that something like an absolute time exists if it can never be precisely measured? |
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Title: Re: Time Post by Sir Col on Mar 5th, 2008, 12:44am We must be careful here as we are using time in two different senses. We can talk about time as an integral part of the essence of matter; that is, the very existence of matter demands the existence of space, which inevitably leads to a temporal separation of its extremes. But we can also talk about time in the distinctions we make between two observable events; for example, the "time" it takes for a sprinter to run 100m or the "time" it takes for an ice cube to melt. Unfortunately any attempt to quantify and measure this time is also based on observed events. As everything is in a constant state of change and the very existence of matter in the universe has an effect of the rest of matter, there are no absolutes. My point before was that even if the universe was made up of the smallest unit of matter then it will have an effect on itself. If it moves (a necessary condition to measure time) then it distorts spacetime in such a way to alter its own "rhythm". |
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Title: Re: Time Post by towr on Mar 5th, 2008, 1:41am on 03/04/08 at 16:33:30, Icarus wrote:
A lot goes unsaid in language usage; it's a matter of filling in the blanks based on (supposed) shared beliefs. If you have a statement like "John is twice as tall as last I saw him", then that also implies there is some unmentioned standard of length with respect to which his height increased. He's not twice as tall as himself, unless he has no dimensions. |
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Title: Re: Time Post by Icarus on Mar 5th, 2008, 8:11pm on 03/04/08 at 21:46:15, BenVitale wrote:
What are you talking about? The time concept I am referring to is observed and is the basis of this physics of time/motion. Perhaps you should define what it is you mean by "absolute flow of time". Quote:
No quantity that is considered continuous has ever been "precisely measured". This has never stopped us from assuming that such quantities exist. on 03/05/08 at 00:44:58, Sir Col wrote:
I don't see your "different senses" as being different. The "time" you measure is the same "time" that is "an integral part of the essence of matter". (I also disagree with the "inevitably" part, but that is irrelevant, since a temporal separation exists, inevitable or not.) Quote:
This doesn't follow. Just because you don't see it, doesn't mean it is not there. If fact, theories of cosmology generally assume an "absolute" time. And our current understanding of physics supplies, theoretically, such a beast. If you look at the overall conglomerate of matter in the universe, it defines an average timeline. Quote:
The distortion is not an alteration of its rhythm, but a part of what defines its rhythm. And distortion or no, it still has a rhythm, which measures its own local time. on 03/05/08 at 01:41:50, towr wrote:
I have no problem with assuming such an absolute standard either. However, no such standard was given in the problem, nor is there one in common knowledge that could be applied to the problem to give it meaning. Without some standard for comparison, "twice as fast" has no definition. Quote:
If you have some shared belief that allows you to fill in these blanks, then I certainly agree that the question is meaningful for you. But I have no such belief, nor am I even aware of one others have that would do so. Quote:
This is not the same thing at all. I do not deny the ability to compare time rates. I mentioned such a comparison in my previous post. Your statement gives a standard of comparison: John's height now vs. John's height when you last saw him. These are two different measures. However, the problem in this thread does not suggest in the slightest what second measure of time we should compare to. |
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Title: Re: Time Post by towr on Mar 5th, 2008, 11:54pm on 03/05/08 at 20:11:22, Icarus wrote:
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Not to mention you found exactly the same criteria that would have to hold for it to make sense. Quote:
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Title: Re: Time Post by Sir Col on Mar 6th, 2008, 12:21am Icarus, I think you've misunderstood most of what I've said, but that is my fault for not explaining it clearly. The different senses I refer to are those relating to (i) the existence of spacetime, and, (ii) our attempts to measure separations on a timeline, which itself is based on an attempt to measure some "absolute". The first sense is not measureable as it simply makes reference to the fact of separation: two distinct parts of matter cannot simultaneously exist at the same point in spacetime. This sense of "time" is absolute, in that it exists, absolutely. However, the second sense is all about our attempts to measure these "absolute" separations, which is relativistic by nature. That was my point. I think towr summarised this perfectly by saying, "I think most people have some sense of external/absolute time; even if they've learned it doesn't exist (or in any case can't be determined)." My point about the rhythm of a body is that its very motion alters the fabric of spacetime around it, hence adjusting the forces that act on it and other bodies. For example, given a single atom, the instantaneous location of one of its electrons has an impact on the forces acting on and around it. |
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Title: Re: Time Post by rmsgrey on Mar 6th, 2008, 7:21am on 03/05/08 at 23:54:12, towr wrote:
In the case of the two Johns, if you could have them both present at the same time, you could compare them directly - a mark on the doorpost is assumed to continue to represent John's former height, but what you actually compare is John-now against doorpost-mark-now and observe that they differ when doorpost-mark-then and John-then didn't... There's no obvious way to compare time-then to time-now - anything we use would be affected by the change in the flow of time - as though the doorpost stretches and contracts to match John's height. |
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Title: Re: Time Post by towr on Mar 6th, 2008, 10:08am on 03/06/08 at 07:21:14, rmsgrey wrote:
I'm not suggesting there's an answer, I'm only suggesting the question isn't meaningless. |
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Title: Re: Time Post by rmsgrey on Mar 7th, 2008, 2:59pm on 03/06/08 at 10:08:25, towr wrote:
In the case of doubling John, you have an implied external reference for length - most solid objects would work as referents. In the case of doubling everything - whether in length or in time - you don't have the (near-) rigid framework to provide a "fixed" context. |
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Title: Re: Time Post by Icarus on Mar 7th, 2008, 5:06pm And the whole argument is irrelevant to my comments since they had nothing to do with whether or not two time intervals are comparable. I assume that they would be. Irregardless of whether you have some external means of comparison (which the person making the remark evidently does), you are still comparing two distinct measurements of John, which are at best only superficially related. My comment was that we are being asked to do a comparison without a second time interval to compare against. And I disagree that we should just grab the first context for a remark that we can find to interpret it. If the context is not provided in the remark, and is not a commonly known and accepted context, then the remark needs clarification from its author. Until such clarification is forthcoming, all such attempts at adding context just lead to pointless arguments with others who have chosen a different context. ----------------------------------------------------------- I suppose this "God's timescale" is what Ben meant by "absolute time". To tell the truth, I missed towr's original posting of the idea when I made my earlier replies. If this is what Ben meant, then I retract my statement of belief in it. I neither believe nor disbelieve in the idea that there is anything unobservable from this universe. |
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Title: Re: Time Post by towr on Mar 8th, 2008, 2:34am on 03/07/08 at 14:59:20, rmsgrey wrote:
And our current level of technology provides all sorts of analogues that can actually fit the idea. Like sped up videos, or simulated worlds, etc. And if our universe is a simulation from a meta-universe, then an external context actually does exist. |
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Title: Re: Time Post by towr on Mar 8th, 2008, 2:56am on 03/07/08 at 17:06:50, Icarus wrote:
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Which isn't to say there might not be a context that gives a significantly different meaning to the question, but I don't see it. Every way I can make sense of the question (god's eye view, computer simulation, video speed-up, etc) gives it the same meaning, so that's what it must mean. |
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Title: Re: Time Post by Icarus on Mar 8th, 2008, 7:45am on 03/08/08 at 02:56:22, towr wrote:
And again I am not demanding EXPLICIT references. My point was that it must have either explicit or IMPLICIT references to be meaningful. This question has neither. Your example is replete with implicit references. Quote:
"First" was a bad choice of wording. "Arbitrary" would have been better. Without some sort of clue as to what he wants a comparison to, any choice you make is arbitrary. Quote:
No. Even this conflict is more over differing chosen interpretations of wording than over choosing vs not choosing. It is just not at the riddle itself that we have chosen our different interpretations. Quote:
Yes, we can interpret the question as meaning against some unknowable "absolute" timescale. But because such a scale is unknowable, it still fails to give the question any true meaning. If there is some knowable common timescale out there, the question would have meaning, but there is no such common scale. |
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Title: Re: Time Post by rmsgrey on Mar 8th, 2008, 7:55am on 03/08/08 at 02:56:22, towr wrote:
...if it means anything. There are plenty of syntactic constructions that, if they meant something, would have a well-defined meaning, but are, in fact, nonsense: "The smallest integer inexpressible with seven words." etc. |
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Title: Re: Time Post by towr on Mar 8th, 2008, 1:23pm on 03/08/08 at 07:55:06, rmsgrey wrote:
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Title: Re: Time Post by towr on Mar 8th, 2008, 1:38pm on 03/08/08 at 07:45:30, Icarus wrote:
Hence I go looking for that external reference whose existence is implied, even though it's nature isn't. Numerous solutions present themselves to the same effect: people inside the universe can't notice changes in (their) time because they're subject to it, only an outsider might notice. Clearly I must be mad to so naturally find my way through an unintelligible maze of nonsense. Quote:
Not to mention it's the same choice you found, yet won't use. Quote:
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For any unknowable absolute timescale one might propose, it seems clear to me that the answer to the question is that no one can tell the difference. Seems meaningful enough to me. |
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Title: Re: Time Post by rmsgrey on Mar 9th, 2008, 9:11am on 03/08/08 at 13:23:27, towr wrote:
So what does it mean? Anyway, the existence or non-existence of some privileged "external time" is moot since, under any reasonable interpretation, whether there is an external time or not, anyone living on internal time won't be able to detect the "change" |
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Title: Re: Time Post by towr on Mar 9th, 2008, 9:46am on 03/09/08 at 09:11:57, rmsgrey wrote:
You have set of 'objects' that satisfy the predicate of being an integer; and a set of 'objects' that satisfy the predicate of being expressible in seven words; and we're talking about an object that is in the intersection of the two sets (thus satisfying both predicates); and as it turns out that intersection must be empty. Next thing you'll tell me you don't know what 'the living dead' means, or 'invisible pink unicorn'. |
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Title: Re: Time Post by temporary on Mar 13th, 2008, 6:03pm on 02/24/08 at 08:48:05, Grimbal wrote:
So time already does move twice as fast because 0x2=0 |
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