Philosophy Of The Cosmos - Metrics
Something occured to me when i was reading about metrics in this weeks reading. I am wondering if the metrics that we measure dimensions by are absolute, or if there is scope for some small margin of 'stretching' of them. We all accept that there is always error in measurement, but the same way that we accept a meter ruler to be 1m even if it is actually 1.03m, could it be that the metrics with which we measure distance can also change within some margin? if this was the case, then maybe time could also speed up or slow down, like we sometimes feel it does, but rather than it just being our perception of time it may actually be the unit of one second shrinking or expanding. it seems to me that while this would be significant to us, in the scheme of things it would not matter— like a negligible error in an experiment.
ps. i dont necessarily think this is happening, i just thought it might be something intersting to think about!
~sharmila
[[red If you're talking about perception, we're not going to have a chance to discuss it much in a cosmology course, because it doesn't affect cosmological measurements (unless I've misunderstood your point). I think your point is VERY interesting, though. I'm hoping to talk about it in a different course next semester!
Jason ]]
[[black I understood the question as perhaps our measurements of dimensions are just - off by a little bit, and this reflects in reality. That is when we feel like time is slower/faster, it is actually the effect of the errors in our measurement and NOT just our perception. I don't know if I've understood and expressed that correctly or not. Nevertheless, I feel that it is rather exciting thinking about uncertainties. On the macroscopic scale it doesn't seem to have a huge effect on the laws of Physics. But if I'm not mistaken it is the Heisenberg uncertainty principle that allows tunnelling which allows fusion to take place in stars. Of course without this we wouldn't have cosmology and what not to study. But I'm not expert on this nor have I learnt this uncertainty…thing. Maybe Jason can help clarify?
u 4677579 ]]
[[blue I would disagree with the previous poster on their assertion that uncertainties don't affect the macroscopic scale that much, seeing as one of the underpinning theories of cosmology currently is General Relativity, which states that all measurements are unique to their frames of reference. Also, as space can itself be moulded by the presence of mass-energy, what is defined as a meter can be very fluid, depending on your frame of reference and what is in that area of spacetime. What/Who is correct if two different observers to the same event say different things?
But as the previous post states, uncertainties in our measurements also exist at the very other end of the scale. The Uncertainty Principle tells us that we cannot know (with any real certainty) one of a particles properties if we know the other with great certainty.
This would seem to indicate to me that uncertainty and ambiguity exist on all levels of the universe from the intergalactic to the microscopic.
Andrew Tait Hallam ]]
[[black Dear Mr A,
We're not on the same page. A link between uncertainties and GR has never ever ever crossed my mind. Or it never crossed my mind in the way you mentioned it. I was not, in anyway, classifying GR as something "macroscopic". When I say macroscopic I meant everyday life objects. The concept of uncertainty as I understand it is an error in my own measurement. If we are in different frames and our measurements differ, I would not call that difference an uncertainty. That is because, as you said, the measurements are unique to each frame - hence they are both correct within their frame. An uncertainty, again, as I understand, is an error in a measurement that I make in my own frame.
Ly u 4677579 ]]
I don't know what the Heisenberg Uncertainty Principle is meant to say. There are lots of versions of it, all vague. Fortunately, it's not an essential part of quantum mechanics. You can do quantum mechanics without it, and that's what we'll be doing. That way we'll be able to clarify which versions of quantum mechanics are epistemic (depend on knowledge) and which ones aren't.
Jason
Our perception of the universe is certainly a very interesting idea to discuss but the idea that time shrinks and expands (if i understand you right) could be considered not so much as perception but bordering on proof of a forth 'time' dimension. But rememeber that while there are indeed errors in our measurements in the 3D would, time is (in) the forth dimension and so whether we can even quantify it from our dimension would itself be a massive debate. But if true, the idea certainly wouldnt be negligible! But to reference Einstein with the idea of 'space-time' that space and time are not independent of one another, that if time did fluctuate (instead of space around massive objects), shouldn't space then change to correct for it (nullifying our perception)? Also referencing the poster above, i believe its Special Relativity that deals with frames of reference, not General Relativity (but by all means correct me if im wrong). Special Relativity also redefined the metre as being a unit based on the speed of light so a much more accurate measure is possible. This brings me to my final point of if our measurements are all affected by perception, why then are there so many accpeted constants in science, from Planck's Constant to the speed of light, which 'seem' to hold true for all?
Adam B u 4839484