# [Basic question] What are negative numbers?

1. Dec 22, 2012

### marxLynx

What are negative numbers? Have you even seen a negative number of chickens? i haven't. The idea is merely an abstraction of subtraction. An abstract idea doesn't have to have any physical significance at all, even if the idea was derived from physical things.

2. Dec 22, 2012

### micromass

Re: [Basic question] What is the 'physical' explanation of a division by a fraction?

Sure I have, if I owe a person 3 chickens, then I have -3 chickens. I'm happy with that physical significance.

3. Dec 22, 2012

### Vargo

Re: [Basic question] What is the 'physical' explanation of a division by a fraction?

And I am happy knowing that negative means down and positive means up. Or maybe the reverse if convenient :)

4. Dec 22, 2012

### cdux

Re: [Basic question] What is the 'physical' explanation of a division by a fraction?

Not only for this as it was answered, I suspect all math has a physical significance.

After all, not only it has physical significance in basics, but the most complex concepts of physics such as quantum mechanics can only be 'thought' through math. For example most physicists admit that they don't understand the uncertainty principle, they just "read it" in formulas. [edit: Meaning not that it's 'abstract' in itself but that they are so convinced everything up to that point had a physical meaning that even something that goes further and they can't see the physical part, it should have a physical representation.]

5. Dec 23, 2012

### HallsofIvy

As I said in your other thread, all mathematics has any different physical applications. Mathematics is NOT physics and there does not exist a single "physical explanation" for any mathematical operation.

6. Dec 23, 2012

### symbolipoint

They are numbers counted or measured in the opposite direction. Usually a reference number can be matched to a reference point on a number line. A simple physical interpretation works for temperature. One of the temperature scales, Celsius, uses the freezing/melting point of water as zero degrees. We can often find or measure a temperature of some positive amount, and if we do, this is usually of a temperature at which water is not a solid (not frozen). We naturally assume these are positive values, to the right of zero on the number line. A NEGATIVE Celsius temperature value is one at which water is typically in the form of ice, and the number is to the left of zero on the number line, and the number is given a negative sign next to it.
Example: -5 degrees Celsius is colder than the freezing point o f water and this water would be ice. 4 degrees Celsius is cold, but water at this temperature will be liquid.