# Uncertaninty in length

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1. Oct 8, 2014

### Quarlep

In Every measurement there must be uncertanity.In lenght or In time everything.Lets assume we have a ruler and a rope.If I measure the rope I get a result but I cant say this is exactly true because theres a unncertanity in measurement.Lets suppoe the rope is 100 cm minus or plus 0.5 mm.The same thing as time or mass and another measurable things.Here comes my question Who are the the source of this error ? We or the universe.

Thanks

2. Oct 8, 2014

### Staff: Mentor

What would "the universe as source of uncertainty" (error is doing something wrong) mean?
I don't think it is useful to look for a source with those two categories.

3. Oct 8, 2014

### mathman

There is some uncertainty due to limitations of our measuring devices. There is also Heisenberg's principle, but this is significant primarily at microscopic levels.

4. Oct 9, 2014

### Quarlep

Is there a body length of the exact number ? No, so theres uncertainty in measurement Here comes my question in universe theres exact lenght and we cant measure it exactly or there's no exactly measurement thats why we cant measure it.

5. Oct 9, 2014

### sophiecentaur

I would say that people are 'in error' when they look for certainly in anything. It may be the fault of the Mathematics we have developed, which seems to indicate an absolute precision that doesn't really exist in the Universe.
How many beans make five?

6. Oct 9, 2014

### Quarlep

I got it.I am agree with you.

7. Oct 9, 2014

### Staff: Mentor

There are no perfect rulers because there is no clear way to define where exactly objects end, and even if there would the length would constantly change back and forth a bit.