# Negative distance? Can it be real?

• Oldblood
In summary: If you map the coordinates to a sphere(like the Earth), that's exactly what you'll get. In summary, the conversation discusses the possibility of negative distance in relation to two planes with different speeds landing on the same airport after a specific amount of time. The formula for the distance between the airports is provided, and the concept of negative distance in relativity is mentioned. The conversation concludes with the idea that negative distance has no physical significance.
Oldblood
I started wondering about this after solving a problem on the exam. Here is the problem: 2 planes has a speed v1 and v2. They are flying from the airport at the same time. The difference between their landings on the same airport is t. Express the distance between the airports as functions of v1, v2 and t.

This is what I got: distance= v1v2t/|v1-v2|

If this formula for the distance between the airports allways applies and we have defined positive and negative velocities as oposite directions when the problem is 1 dimensional, we get a negative distance if the planes goes in oposite directions and lands on the same airport after a time t.

So here is my question: May there be such a mystic thing as negative distance so that 2 planes can go in oposite directions and land on the same place after a finite amount of time? Could this be something physical, not observed in our universe, but still real in other strange universes and extremely hard for us to imagine?

No need for weird alternate universes to have the two aircraft heading in opposite directions land in the same airport. If you map the coordinates to a sphere(like the Earth), that's exactly what you'll get.

In relativity, the usual notion of distance is replaced by the invariant interval, which can be negative. The invariant interval between two events is (in +++- convention) the square root of
$ds^2=dx^2+dy^2+dz^2-c^2dt^2$
This is just the usual notion of distance minus an extra term for the time difference between the two things you are measuring. If you are measuring the interval between two things at the same time, then ds is just the distance. A negative interval means that the interval is time-like, which means it's possible for a signal to travel from one endpoint to the other without going faster than c.

Hey,

You are thinking too hard.
It has no physical significance what so ever

http://www.datasea.info/avatar1.jpgNo need for weird alternate universes to have the two aircraft heading in opposite directions land in the same airport.

## What is negative distance?

Negative distance is a concept in mathematics and physics that represents the opposite direction of a positive distance. It is used to describe the distance between two points in a coordinate system, with one point being located in the negative direction from the other point.

## How is negative distance measured?

Negative distance is measured using the same units as positive distance, such as meters or kilometers. However, the direction of measurement is reversed, with negative distance being measured in the opposite direction from the positive distance.

## Can negative distance be real?

Yes, negative distance can be a real and valid concept in mathematics and physics. It is commonly used in equations and calculations, and has been proven to accurately describe the distance between two points in a coordinate system.

## What is the significance of negative distance?

Negative distance is important in many fields of science, such as physics, engineering, and mathematics. It allows us to accurately describe the position and movement of objects in a coordinate system, and is essential in solving complex equations and problems.

## Can negative distance have a physical representation?

While negative distance itself does not have a physical representation, it can be seen as a representation of motion or direction in a coordinate system. For example, an object moving in the negative direction would be described as having a negative distance.

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