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Does absolute measurement only exist in the mind?


Alex Mercer

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Was thinking about how people measure stuff to find their length, width, weight etc and was wondering if there is something that describes the fact that we can't measure things to exact numbers. Like measuring things with a 60cm ruler is only approximating it right? I was wondering if this applies to all things that require measurements in the world, even experiments that we do, even examining the speed of light. How can we perfectly measure something if we are always trying to find an exact point to which to measure to and from (that doesn't exist). And with my limited knowledge I know that at quantum scale there are sub atomic particles and I think these have no fixed position so even if we go all the way to the tiniest scale, what are we even measuring? So what are your thoughts, is this a common question that has already been answered? Just left we me wondering about

Thanks in advance humans!

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Quantity of objects is exact integer number (unless multiverse or parallel universes are introduced).

At quantum level everything changes and do it very fast in human terms. One measurement you have neutron, in another you may have decay of unstable isotope in which neutron was part of nucleus, and your previous measurement no longer represents current state.. 

Edited by Sensei
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8 minutes ago, Sensei said:

Quantity of objects is exact integer number (unless multiverse or parallel universes are introduced).

Counting is often (but not always) an exact science.

Don't forget the counting numbers.

+1

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Ok thanks sensei. But how does that explain that quantity of objects is always whole number. How do we even know that we are measuring exactly. Are current tools we use so precise?

I searched up the question on Google and it came up as a similar question on quora. The answerer said that it is like trying to find the measurement of an object with infinite precision (I remember learning about some of this such as precision accurate and significant figures). Then it talks about how all the quantum particles in the object are moving around so no exact point to measure from and so if we tried to freeze them to get an exact point, it is impossible to do. It then says due to Heisenberg uncertainty principle, ultimately that  however accurately we measured the object, you cannot know exactly where it is, because the universe will not allow you.

 

I don't know if that applies to speed of light or photons. How do we know the speed of light is constant if we cant measure it to an exact degree or can we? Isnt there always percentage error in physics due to inaccuarte nature of tools or how universe is

Edited by Alex Mercer
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20 minutes ago, Alex Mercer said:

Ok thanks sensei. But how does that explain that quantity of objects is always whole number. How do we even know that we are measuring exactly. Are current tools we use so precise?

Old saying

"Don't count your chickens before they are hatched."

I have one broody hen sitting on four eggs.
How many chickens have I got ?

 

When counting we can generally agree if

1) The numbers are small  eg I have 5 apples in this bag.

2) The objects being counted are well defined (eg 5 apples)

3) The counts are not averaged.

 

So

1) Large numbers. I doubt that anyone has ever enumerated all 23 digits of Avogadro's number, although it is an exact number .

2) How many rivers are there in the United states ?  It depends on your definition of river?

3) Many objects eg insect populations are measured by counting per square cm for lots of square centimetres and averaging. This will not in general result in a whole number.
Sensei's example of a geiger counter is also an averaged result.

 

 

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What about with matter and light. Fundamental stuff of our so called reality. Like trying to measure speed of light or the size or mass of a sub atomic particle. Why and how is that always whole integers if infinite precision is impossible. 

 

 

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25 minutes ago, Alex Mercer said:

What about with matter and light. Fundamental stuff of our so called reality. Like trying to measure speed of light or the size or mass of a sub atomic particle. Why and how is that always whole integers if infinite precision is impossible. 

 

 

But these are not whole numbers.

Do you understand this mathematical notation  3 x 108 metres per second ?

Do you think this means exactly 300,000,000 m/s   ?

Of course it doesn't.

But mostly we work using numbers between 1 and 100 or 1 and 10 and multiply by a power of 10. That is accurate enough for many purposes.

It was also  the subject of my last post ( Avogadro's number 6 x 1023) which I certainly don't want to write out or even know to 23 digits.

Edited by studiot
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4 hours ago, studiot said:

2) How many rivers are there in the United states ?  It depends on your definition of river?

The same like with my quantum scale decay example - some rivers appear, some rivers occasionally disappear, e.g. rain/dry weather and their quantity changes..

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Two different constraints in play here.

Measuring anything to an arbitrary precision is known as the 'measurement problem', which, as Swansont explained, is due to the limited precision of our measuring equipment/experiments,is the first constraint. New technology and fresh ideas help kick this can down the road until we hit the next roadblock..

The other constraint is inherent in quantum systems, and represnted by Heisenberg's uncertainty Principle.
It states that certain aspects of reality itself cannot be measured to arbitrary precision, and that is a propertty of the system, having nothing to do with the method of measurement

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1 hour ago, Alex Mercer said:

I was told that the speed of light is not measured quantity but a defined quantity. I don't get how you can just define the speed of light without some type of physical measurement? 

Are you sure that is what you were actually told ?

Was your source actually saying that the speed of light is invariant ?

I said that the speed of light was measured at 300,000,000 m/s.

But you could change the units so that it is exactly 1. You would of course not be measuring distance in metres and time in seconds.

Please note there is an important difference between absolute, constant, and invariant.

Do you know what this is ?

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