How would this universe be if there's NO UNCERTAINITY PRINCIPLE

[aditya23456]

how would this world appear like if energy,time &&& momentum,distance can commuate...and anyone please describe relation between energy and time

 

[Ger]

Universe would be completely static and invisible. The same as nothing. There is a relation between energy confined to a space (the confined energy named mass as in m= E/c2). That same energy is creating the space and the time associated with it. Start of time is with every event which takes place in that mass system and time it takes to distribute mass/energy into that same space.

 

[shreyakmath]

The uncertainty principle must exist for a dynamic universe.
If a universe doesn't obey the uncertainty principle, then there shall be no quantum fluctuations. The spacetime would be a static one

 

[tiny-tim]

a more realistic question would be …

how would the universe be if Planck's constant were very much smaller? ​

 

[bhobba]

I don't think atoms as we know it would exist - the electron would spiral into the nucleus.

Thanks
Bill

 

[Ger]

a more realistic question would be …

how would the universe be if Planck's constant were very much smaller? ​

More realistic yes. But than it would make no difference at all. Typical QM effects would be much smaller. The maths do not change. Convinient is to substitued h=c=1 in the maths to get rid of those many constants in formulas.

 

[bhobba]

More realistic yes. But than it would make no difference at all. Typical QM effects would be much smaller. The maths do not change. Convinient is to substitued h=c=1 in the maths to get rid of those many constants in formulas.

Yes - but if say objects like atoms etc remained the same size then they would behave differently - if planks constant was much smaller quantum effects would not hold for the distances between electrons and the nucleus and they would spiral inwards and decay.

Thanks
Bill

 

[Ger]

All other things scale with the values proposed for h and c. Set the light speed at a 300 km/hr and special relativity will become a part of daily life

 

[bhobba]

All other things scale with the values proposed for h and c. Set the light speed at a 300 km/hr and special relativity will become a part of daily life

And you don't think that would be change in how the universe behaves?

Thanks
Bill

 

[Ger]

And you don't think that would be change in how the universe behaves?

Thanks
Bill

Does the setting of h=c=1 change something in the maths employed? I don't think so. Only a value of h=0 (removes the uncertainty at all) would defintly change the physics, as does it do for the maths as well.
The behaviour of the universe is one of changes which we try to measure and can observe. That is described by excatly the same maths as before. So why should behaviour change?

 

[bhobba]

Does the setting of h=c=1 change something in the maths employed? I don't think so. Only a value of h=0 (removes the uncertainty at all) would defintly change the physics, as does it do for the maths as well.
The behaviour of the universe is one of changes which we try to measure and can observe. That is described by excatly the same maths as before. So why should behaviour change?

No it doesn't - but in changing the units (which is what you are suggesting) the value of the size of things like you, me and atoms is now different - you are implicitly assuming they remain the same - they don't. The value of planks constant sets the size limit where quantum effects start to occur - change that and the world will be a different place - the same with the speed of light - change its value relative to the speeds of everyday experience and the world will be entirely different.

Thanks
Bill

 

[Ken G]

Does the setting of h=c=1 change something in the maths employed? I don't think so. Only a value of h=0 (removes the uncertainty at all) would defintly change the physics, as does it do for the maths as well.
The behaviour of the universe is one of changes which we try to measure and can observe. That is described by excatly the same maths as before. So why should behaviour change?

We can set some of the constants to 1 if we choose, but we cannot set them all to 1 without changing the universe. This is because the constants can be joined into unitless numbers, like the fine structure constant "alpha", and if a number has no units, then we are not free to choose its value. So you can set h=c=1, but the fine structure constant also depends on the charge of the electron, so you would then have to take that charge to be the square root of 1/137, you have no choice. So the problem is, what do we mean by h being "small"? Small compared to what?

Thus, there are actually several ways to answer the OP, depending on how we take its meaning. We could take the meaning:

Interpretation #1: Keep all the physics we know the same, but make h much smaller, in the same unit system we use now. In particular, this requires that alpha be made much much larger, and so atoms become completely different, possibly even impossible as bhobba said.

Interpretation #2: Replace our physics by some other version that does not include an uncertainty principle. This is harder to answer, because if we are going to change the physics, we can do anything we want, especially if we allow the observations to be different! We would thus have to say that the observations stay the same, so the universe is the same, but it is explained without an uncertainty principle, and this is not what the OP asked. We could nevertheless change physics back to what we thought it was prior to the discovery of the uncertainty principle, i.e., change it back to Newtonian physics, and ask how we might have proceeded without an uncertainty relation. However, Newtonian physics was not a complete description-- it had paradoxes it could not resolve, like why don't atoms spiral into themselves. So without an uncertainty principle, we'd need some other principle to prevent this, and we're off to inventing new physics of the type that many were speculating about pre-1900. I don't know if anyone came up with something that could have worked but didn't agree with observations, but we know that no one came up with something that did agree with the observations, so we'd be kind of stuck at this point!

 

[Vanadium 50]

Ger has it in post #10: set h = 0 to see. And yes, that would have enormous effects, such as the Rydberg becoming infinite.

 

[ImaLooser]

a more realistic question would be …

how would the universe be if Planck's constant were very much smaller? ​

Something tells me that this is beyond human capability to know.

 

[Vanadium 50]

No, one can calculate this. Now, one also has to be a bit careful, because one needs to carefully specify what is being held constant and what is not. But given that, it is calculable.

 

[Ken G]

The problem is, you'll quickly run into the "anthropic principle." If you change h by too much (typically only a few percent can present a problem!), then we no longer find it possible to have anything that we would recognize as human intelligence. Immediately we run into the difficulty of how much of quantum mechanics depends on the kinds of questions that human intelligence is interested in answering, as opposed to some other kind of intelligence (or worse, no intelligence at all, if h is changed to a point where intelligence itself is impossible). When we encounter that problem, no self-consistent calculation is possible any longer, because it would have to use quantum mechanics, and quantum mechanics would not be applicable if the kinds of questions it answers are not questions that can be posed in that universe.

 

[lugita15]

how would this world appear like if energy,time &&& momentum,distance can commuate...and anyone please describe relation between energy and time

See this paper here, from the American Journal of Physics, for an attempt to prove that the operators like position and momentum cannot possibly commute, and thus quantum mechanics is in some sense necessary. (Actually, he doesn't show that the operators don't commute, rather he tries to show the equivalent statement that such operators cannot have simultaneous eigenstates.)

 

[ImaLooser]

No, one can calculate this. Now, one also has to be a bit careful, because one needs to carefully specify what is being held constant and what is not. But given that, it is calculable.

Sure, you can calculate this. But no one knows what the universe would look like.

 

[Vanadium 50]

What is the difference between being able to calculate something and knowing what it looks like?

 

[Ken G]

I would still say that if you calculate something using certain postulates, and obtain a result that does not make it possible for you to exist, then your calculation has no meaning because you know the postulates do not approximate anything useful or physically meaningful. What does it serve you to do a calculation that you know results in a useless conclusion? It would be incorrect to say "in my calculation, the universe would be like X" if X does not include a person who can do that calculation-- the conclusion that the universe would be like that, based on application of that physics, is then internally inconsistent and meaningless. Instead, you could calculate the range in h for which quantum mechanics could be the correct physics of any universe, and say that outside that range, you know quantum mechanical calculations cannot mean anything. Typically, such ranges are astonishingly narrow! The same argument can be leveled as a criticism as a concept of a "multiverse" being used to "explain" why we find ourselves in such narrow ranges.

 

[ImaLooser]

What is the difference between being able to calculate something and knowing what it looks like?

I don't think anyone could deduce or infer the nature of human life from quantum mechanical calculations. Think "emergent phenomenon."

 

[ImaLooser]

I would still say that if you calculate something using certain postulates, and obtain a result that does not make it possible for you to exist, then your calculation has no meaning because you know the postulates do not approximate anything useful or physically meaningful. What does it serve you to do a calculation that you know results in a useless conclusion? It would be incorrect to say "in my calculation, the universe would be like X" if X does not include a person who can do that calculation-- the conclusion that the universe would be like that, based on application of that physics, is then internally inconsistent and meaningless. Instead, you could calculate the range in h for which quantum mechanics could be the correct physics of any universe, and say that outside that range, you know quantum mechanical calculations cannot mean anything. Typically, such ranges are astonishingly narrow! The same argument can be leveled as a criticism as a concept of a "multiverse" being used to "explain" why we find ourselves in such narrow ranges.

It could be leveled as a criticism, but not all that convincingly. I don't see why the calculation has to be done by a being that is inside that universe and is meaningless if done outside that universe. I don't see what difference it makes.

You might say that such things are "too speculative," but this is a matter of opinion.

 

[lugita15]

Does anyone have any thoughts on the paper I cited in post #17?

 

[bhobba]

Does anyone have any thoughts on the paper I cited in post #17?

Gave it a quick squiz - to really understand it I will need a lot more carefull study.

But my initial reaction is its pulling assumtions out of thin air and saying they have derived QM. They havn't really. For example look at the straight line describing probabilities - that is basically the L1 norm ie the norm of standard probability theory expressed in vector space language. Then they consider a circle and start using that - its basically the L2 norm of QM. Why choose either? Of course its to arrive at the right answer - but they are not making exactly what they are assuming explicit and saying this is a key assumtion of QM.

My approach is a little different - it is based on invariance but at each step the precise assumption being made is stated explicitly. For example the use of complex numbers follows from the requirement to allow continuous transformations of the vector space. Consider an infinitesimal transformation - it must have the form U = 1 + A dt where dt is infinitesimal. Since it transforms an orthonormal basis to an orthonormal basis U(bar) U = 1 which implies A = -A(bar) so that A is pure imaginary ie complex numbers are re-required. Here each assumption is stated explicitly eg it transforms an orthonormal basis to an orthonormal basis - I can justify it by assuming the mapping of states to an orthonormal basis is arbitrary but it is a key assumption.

And no I will not post my approach in full detail - or even really give anything more than a broad outline which I already have done because I really can't motivate myself to do the grunt work required to spell it out in detail on paper - might do it one day - but not now.

Thanks
Bill

 

[Ken G]

It could be leveled as a criticism, but not all that convincingly. I don't see why the calculation has to be done by a being that is inside that universe and is meaningless if done outside that universe. I don't see what difference it makes.

The point is that what is demonstrably true is that an intelligence (or call the computing agent anything you like) is necessary to do that calculation. So I am not assuming anything to make this claim-- rather, it is those who like to imagine that calculations exist independently from the intelligence that did them who are making the assumption. They are assuming that I can use the laws of one universe to operate a brain that can do a calculation that will then have something to say about the laws of physics in some other universe. But there is no basis for that assumption, for it is demonstably internally inconsistent (one set of physical laws is drawing conclusions about some other set of physical laws). That's why it has to be possible to do the calculation within the universe in question for it to have any meaning-- otherwise, we are only assuming that it has meaning though we know it is not consistent.

 

[Ken G]

Does anyone have any thoughts on the paper I cited in post #17?

My feeling was that it did contain insights, but it had about two pages of insights embedded in 15 pages of text, which made it a little hard to read! I can see what bhobba is saying also, I feel that these insights can be packaged in different ways and it's good to be exposed to them in any package. But what is still missing is a really concise version that cuts right to the heart of the issue. I think I would start with the idea of superposition of probability amplitudes-- once we establish that our theory will have that structure, the rest pretty much follows from fairly natural requirements (like bhobba's need to have continuous possible states evolving smoothly into each other).

 

[ImaLooser]

(one set of physical laws is drawing conclusions about some other set of physical laws).

? Physical laws can't draw conclusions.

 

[Ken G]

? Physical laws can't draw conclusions.

If you hold that physical laws govern behavior, which is quite central to the kind of thinking behind the multiverse, then you hold that physical laws govern the drawing of conclusions, because that is a behavior also. Indeed, multiverse thinking, being entirely rationalistic, must hold that nothing does anything except physical laws.

 

[ImaLooser]

If you hold that physical laws govern behavior, which is quite central to the kind of thinking behind the multiverse, then you hold that physical laws govern the drawing of conclusions, because that is a behavior also. Indeed, multiverse thinking, being entirely rationalistic, must hold that nothing does anything except physical laws.

Entirely rationalistic, eh? That's what they all say.

 

[Dickfore]

I don't know.