It appears you are saying that there is a preferred reference frame, that motion should be judged relative to the most influential gravitational mass.Quote:
Originally Posted by Yarin
That implies that there is something special about the planet. You said:
The platform is moving along with the planet, hence no "movement" / time dilation, but the orbiter is moving
contrary to the planet, hence "movement" / time dilation.
That could only be true if there were absolute motion.
At least in regard to time dilation, yes.Quote:
Originally Posted by megafiddle
Only insomuch as the planet is hypothetically anchored.Quote:
Originally Posted by megafiddle
Example: When you drive a car at 80mph, as you know, your car is actually travelling ks and ks of mph through space, around the sun along with the planet. But we don't say that, nor do we even consider that when reasoning about physics of such objects here on Earth, because Earth is our anchor, or as you put it, reference frame.
Obviously, we do this because Earth's gravity dominates the relevant space. I purpose that the effects of time dilation from movement can be anchored in the same way.
EDIT: Not claiming that there is actually any truly absolute movement, location, rotation, distance, etc.
Thanks for clarifying.Quote:
Originally Posted by Yarin
If you mean that the gravitational source should be used to determine the amount of time dilation,
then that is true. But that can be observed from any refernce frame. And all are equally valid.
Certainly you would use the one you are in if that is your vantage point of interest.
But the reason we can do that is not because of the gravitational field. It is because any reference frameQuote:
Originally Posted by Yarin
is just as valid as any other. We could use the moon and still observe an equally valid reality.
The effects of time dilation will appear one way from the earth and another way from the moon. Both are
real.
Not sure if I'm misunderstanding though.
Well I guess then GR represents individuality and unity in One. Everything is One since all is part of the space-time continuum. And Yet all is Individual since any singular perspective is valid. @megafiddle You said there is no Absolute or more important frame of reference. But what frame of reference is used when cosmologists treat the Universe as a singular object?
They can't really. The speed of light will determine also the speed at which we can gain information.Quote:
Originally Posted by gemera
I don't think you need one. You can imagine that the whole universe travels with the speed of light from an imaginary "God's frame". We can just claim that our frame is actually "stationary" and the imaginary "God's frame" is actually the one moving with the speed of light. We are also not fully aware of everything in the Universe to ever treat it as a singular object. Dark energy and dark matter shows that there is more to it than thought a few years back.Quote:
Originally Posted by gemera
That is what I meant about not being able to claim simultaneity of the events. Think on how the whole thing will seem from one of the twins point of view and how it seems from a stationary observer which describes it the way you did. For the stationary observer time will dilate the same for both twins due to the whole symmetry. For a twin's point of view though the other twin (and stationary observer) is accelerating/decelerating since their speed is constantly changing direction, so their "passing of time" constantly changes. Sometimes it seems slower, sometimes it seems faster. If we imagine that each twin changes their speed by a function v(t) that is the same for both, you could calculate the sum of relative dt. That sum will be found the same (I believe). So no paradox.Quote:
Originally Posted by megafiddle
I think your description of "lagging" fits perfectly here, sorry to doubt you before :) The information travels here also with the speed of light, which is comparable to the moving observer's speeds. So when one sees the photon bouncing back to them that means that it has left the other spaceship actually at a different time. So lagging of time seems suitable and it will be the same lagging for both observers. When they are both in the same frame then the effect of their motion doesn't affect time. So they can simultaneously look at each other's clock and get the same time. There is no lagging in this case.
That is also the main reason there is the claim that information doesn't travel faster than light. That would break the theory of relativity due to these kind of paradoxes. Even if you look at quantum teleportation where an effect can travel instantaneous (thus faster than light) to actually read the effect we need some information. Which we cannot get with a speed faster than the one of light.
Nor we could ever be. Or God for that matter (or a Demon, as another paradox names it).Quote:
Originally Posted by C_ntua
Limitations of space:
Imagine a supercomputer that knew every single atom on the universe and stored that information in its memory. Now the Supercomputer has a problem. To truly know everything about the universe the supercomputer needs to know also the location of every of its own atoms, including its memory banks. But then this information needs to be stored in new memory, which itself would require new information to be stored, ad aeternum.
Limitations of Time:
The above is a simple representation of the problem that could be easily translated to any creature brain. But there are other considerations. Information travels at the speed of light. A photon has to reach the supercomputer for the information it carries to be stored. At the speed of light we know distances become 0. But we know that this says nothing about time. So a stationary supercomputer would still have to wait for this information according to its own time frame of reference, much like we need to wait for information when our astronauts go to the Moon. So, our supercomputer couldn't know everything in the Universe. Information would come dripping like the light of the different stars we observe on the night sky. In order for it to really know everything about the universe, our supercomputer would need to be travelling at the speed of light to be able to be everywhere in the universe and collect that data. But... only light can travel at the speed of light, not supercomputers.
Every measurement of time requires motion. In space in between large systems there is a large absence of motion. If time itself is only measured by its affect on objects then objects must interact in order for time to be measured in its passage.
Now time could exist in its passage completely seperate from our existence.
But because the ability to measure time is conditional to something that is subject to time, then it's measurement itself can never be accurate. The unfortunate part about our situation is that we aren't even anywhere near as close to time in that loop either. How are we to even assume to understand things that we cannot measure and cannot simulate. This is where a concept of relativity and uncertainty must be inserted to explain why no two measurements are the same and no two experiments are the same. Start throwing the human 1/10 nueron misfires into the equation and any result is going to get messy.Code:for(int CurrentTime = StartOfTime; CurrentTime < EndOfTime; CurrentTime++)
{
if(People.AbleToMeasureTime())
People.MeasureTime();
}
Does a human know where itself is without violating this? The concept of entropy memory storage shows that the system as a whole could be reduced in its storage by denoting its most common numeric frequencies occuring within the system. The supercomputer would be the system. Its just unfortunate that 90% of the computers memory would be storage of the data (dark matter? lol).Quote:
Limitations of space:
Imagine a supercomputer that knew every single atom on the universe and stored that information in its memory. Now the Supercomputer has a problem. To truly know everything about the universe the supercomputer needs to know also the location of every of its own atoms, including its memory banks. But then this information needs to be stored in new memory, which itself would require new information to be stored, ad aeternum.
What if I suggested inifinities and paradices is our inability to finish measuring or counting something rather than a flaw in the system as a whole. Basicly infinity could be thought as the difference between the amount of space needed to know everything in the universe and the amount of space we possess as a species in unision (because obviously not every human being contributes to a positive advancement).
Our number systems will advance (beyond a decimal is a must to preserve space when denoting large numbers and still maintaining 100% accuracy rather than scientific notation rounding) and our ways of measurement will change. Concepts of impossibilities through contradiction will die as we discover measurable truths. But the concepts are very stimulating none the less and lead one to create the experiments needed to prove reality to each other.
Reality in itself is a constant and any infinity or paradox is merely our lack of ability to account for every situation accurately.
If you believe that the laws of physics are constant, that is not entirely true as we can predict where atoms go without needing to observer and store their path. If I tell you there are 1000 objects with this exact same attributes one being apart from the other exactly a given space, you wouldn't need to store each and every object.Quote:
Originally Posted by Mario F.
Assume thus that there is a Demon that lived from the beginning of times and had built a supercomputer. The Demon find out the laws of physics and about themselves and also built a supercomputer. It comes across matter before the Big Bang and measures all its atoms and stores it in the supercomputer's memory. Since the Demon has all the information about the laws and matter they could predict everything that will happen ever. Lets assume that there is no external energy or matter, there is no God that would change the equations and free will doesn't change anything either. No way to prove they don't exist, but no way to disprove this either. In this case what the Demon cannot do is store the location of each atom in the super computers memory. But is it wrong to say that he knows it? I know how an infinite series of bits going 101010... are even if I cannot possibly store infinite bits in my brain.
I assumed somehow you can see the Universe when its static and when matter doesn't move away from each other creating a race condition. If that time existed and the Demon was there then they could know by predicting. I also mentioned the limitations of quantum teleportation but that could be just our own current limitations. The Demon doesn't need to be limited by the uncertainty principle. It does if it was to observer the world the way we observer it, but imagine if it could use somehow vision with particles much smaller than the observable matter in the sense that their interaction wouldn't practicaly affect the state if matter as we can perceive it. In this case there is an imaginary transfer of information faster than the speed of light. Or you can simply state that those imaginary particles could by definition travel faster than the speed of light.Quote:
Originally Posted by Mario F.
But lets see this purely philosophical. Imagine an omnipotent and all-knowing God. Then you ask him, "hey, can you create a box that you I can hid something from you?" If God could, then he wouldn't be able to see inside the box, thus not being all-knowing. If God couldn't, then there is something God cannot do, so cannot be omnipotent. If you remove the omnipotent or the all-knowing, then there is no problem (this is a whole other discussion itself...). So lets just say that God was only all-knowing. Could you ever prove that there is something God doesn't know? No. Could God prove that they are all-knowing? No, since God cannot know what they don't know. You could safely state that God just believes they know everything and that there could be something they will find out in the future. Or something that exists but God can never find out.
As humans we learn more and more, yet we keep having more and more questions. There could be a time that we have answered all our current questions and we have no answers. Unlikely, but not impossible. At that time, could we not claim that we are all-knowing in the way we describe a God being all-knowing? To say it differently, if I was a being that could only observer one thing, if I could see all there is to that one thing, wouldn't I get the impression that I know everything from a scientifically point of view? I could say there is something else I haven't discovered, the same way humans say there is a God we cannot fully perceive, but that is beyond science from my point of view. As long as we don't have an indication of an existence of something we claim it as "non existent" in the context of science, bottom line being that we define what we "can know". Since we define what we "can know" and we define what we know, it is entirely up to as to claim that we know or we don't know everything.
I believe it would be no different than any other reference frame. The reference frame is basically just a vantage point.Quote:
Originally Posted by gemera
It's important property is that one single set of physical laws apply to any and all reference frames. There is no test that
you can perform to determine if you are "really" in motion or not. Hence no absolute motion.
Or do you mean a reference frame in some other way? Something other than as it's used in special relativity?
That sounds rights. It seems that must be the case.Quote:
Originally Posted by C_ntua
Really? Well, those aren't my thoughts. You may want to argue against the time and space impossibility of a supercomputer that knew everything about the universe. But you'll need to find a theoretical physicist for that.Quote:
Originally Posted by C_ntua
In any case, to refute your argument, look more closely at it. Now look more closely at how a all-knowing supercomputer is an impossibility due to its space and time limitations as argued by theoretical physicists (sorry for pushing the argument from authority buttons, but I can't help since it's a far more elegant argumentation that what I personally could). Now... would your demon ever be able to build such a machine? He wouldn't. Exactly because of the limitations imposed by it. There was no new matter since the big bang. All matter that exists today, existed then. So that supercomputer would face then the same impossibility of existence as it faces now.
No, not really. You are confusing a general knowledge of the rules of the universe, which is what human knowledge seeks, with omniscience which is the attribute some give to God. We describe a God all-knowing as being omniscient. Having infinite knowledge. The box you speak a little above is a known thought experiment that tries to refute both omnipotence and omniscience.Quote:
Originally Posted by C_ntua
Maybe I should have framed my question more clearly. I had in mind the big-bangQuote:
Originally Posted by megafiddle
theory. Cosmologists create models using GR and are able to calculate certain
values like the age of the Universe and its size and thus how much of the universe we can
actually observe etc.
They are also able to replicate the expansion of the Universe etc.
So all these measurements must take place in a frame of reference.
And wherereas I agree that that the laws of GR are the same for all observers and
no frame of reference is more valid or special than another, it just seems that the
actual frame of reference in which the whole Universe is expanding could be described
as a 'special' frame of reference.
And could be used as a default absolute against which other frames could be measured?
For instance suppose we hypothesise alien cosmologists all over the universe as well.
Presumably it would not matter what frame of reference cosmologists all over the Universe
were actually in - if the theory is correct - they should all agree about this reference
frame of the expanding universe?
Not completely sure about this, but I believe the universe's origin, history, age, etc. are referenced to ourQuote:
Originally Posted by gemera
own position in the universe and it's current state. So the age for example is based on time as it currently
progresses, and it's size is based on what we can see in all directions (and extrapolate beyond that).
All of this works as if we are at the center of the universe, which in effect we are. But still there is nothing
special about this; any point in the universe can claim to be at the center.
In the Big Bang model, there is nothing external to judge it by. It can be judged only in reference to itself.Quote:
Originally Posted by gemera
In that case the alien cosmologists will all agree on general characteristics of the universe, because they
are in equivalent reference frames. They will disagree though based on the relative motion that they share
with each other. Each is at the center, and each sees the others are receding away from himself, along
with the rest of the universe.
I'm pretty sure the big bang theory is not extrapolated from our
own reference system, or position in the universe.
Well, apart from the actual cultural/scientific/math units of measurement etc of which any alien species would have their own equivalent, and also the observations that led to the theory in the first place.
But if alien cosmologists were to follow our own lines of enquiry they would have an equivalent of GR and end up with similar models of the Universe, which they could THEN use to extrapolate to their own local systems. Which is what cosmologists on earth do.
Maybe.
Are you saying there could be reference frame outside of the universe's origin?
That there is some observation point where the Big Bang itself could be observed?
That is what I would disagree with. In my understanding of relativistic space, there is nothing outside our universe,
nor was there ever anything outside of it. There was nothing here at all until the "explosion" of the cosmic egg. And
then there was only what was in the "sphere" of the expanding universe.