Negative distance? Can it be real?

  • Context: Undergrad 
  • Thread starter Thread starter Oldblood
  • Start date Start date
  • Tags Tags
    Negative
Click For Summary

Discussion Overview

The discussion centers around the concept of negative distance in the context of two planes flying in opposite directions and landing at the same airport after a certain time. Participants explore the implications of this idea within various frameworks, including classical mechanics and relativity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant presents a formula for distance based on the speeds of two planes and their landing time, suggesting that negative distance could arise if the planes are moving in opposite directions.
  • Another participant argues that mapping the coordinates to a sphere, such as the Earth, allows for two aircraft heading in opposite directions to land at the same airport without invoking alternate universes.
  • A third participant introduces the concept of the invariant interval from relativity, explaining that it can be negative and relates to the time difference between events, suggesting a different understanding of distance.
  • One participant dismisses the idea of negative distance as having no physical significance, suggesting that the concept is overly complicated.
  • A later reply reiterates the previous point about the spherical mapping of coordinates without further elaboration.

Areas of Agreement / Disagreement

Participants express differing views on the significance and implications of negative distance, with some supporting the idea and others rejecting it as irrelevant. The discussion remains unresolved, with multiple competing perspectives present.

Contextual Notes

Participants rely on different interpretations of distance, including classical and relativistic frameworks, which may depend on specific definitions and assumptions about the nature of space and time.

Oldblood
Messages
16
Reaction score
0
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?
 
Physics news on Phys.org
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.
 

Similar threads

Undergrad The Plane in the Wind Puzzle: Does a Constant Wind Affect the Round Trip Time?
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Drag equation - relative flow velocity
  • · Replies 11 ·
Replies
11
Views
4K
In-Flight Incident: My Experience with a Throttle Malfunction | Pilot's Story
  • · Replies 13 ·
Replies
13
Views
4K
High School Airplanes Landing & Altitude Problem
  • · Replies 3 ·
Replies
3
Views
2K
Doublet flow in Fluid Dynamics between two spheres or cylinders
  • · Replies 0 ·
Replies
0
Views
2K
Graduate Calculate the work done by pressure rupturing a spherical containment
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad Solving Sub-Problem for OpenAI Lunar Lander v2: Seeking Advice
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad Trajectory collision calculation
  • · Replies 6 ·
Replies
6
Views
2K
Find the height of a lamp based on the velocities of projectiles
  • · Replies 40 ·
2
Replies
40
Views
3K
High School Sign conventions in torque and non-uniform circular motion
  • · Replies 1 ·
Replies
1
Views
2K