# What is Spacetime diagram: Definition and 26 Discussions

A spacetime diagram is a graphical illustration of the properties of space and time in the special theory of relativity. Spacetime diagrams allow a qualitative understanding of the corresponding phenomena like time dilation and length contraction without mathematical equations.
The history of an object's location throughout all time traces out a line, referred to as the object's world line, in a spacetime diagram. Points in spacetime diagrams represent a fixed position in space and time and are referred to as events.
The most well-known class of spacetime diagrams are known as Minkowski diagrams, developed by Hermann Minkowski in 1908. Minkowski diagrams are two-dimensional graphs that depict events as happening in a universe consisting of one space dimension and one time dimension. Unlike a regular distance-time graph, the distance is displayed on the horizontal axis and time on the vertical axis. Additionally, the time and space units of measurement are chosen in such a way that an object moving at the speed of light is depicted as following a 45° angle to the diagram's axes.

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1. ### I Why am I getting the wrong conclusion from my spacetime diagram?

On my diagram, a person is traveling in a spaceship to the right in red, which is displayed as a Minkowski diagram . At the origin (0,0) the person traveling travels by a stationary person. And the 2 blue lines are the worldlines of two blue stationary rocks. But when I try to figure out what...
2. ### I Gamma - A Minkowski Spacetime Diagram Generator

Gamma is a Minkowski spacetime diagram generator. I probably started this project in August and have been working on it almost full-time since. It will be a free, open-source application. The program can draw all the usual things: axes, grids events, and worldlines, etc. It's easy to create...
3. ### I Clarification on Rindler coordinates definition

Hi, starting from this post Basic introduction to gravitation as curved spacetime I would ask for a clarification about Rindler coordinates. From this wiki entry Rindler coordinates I understand that the following transformation (to take it simple drop ##y,z##) T = x\sinh{(\alpha t)} ...
4. ### I Request for Input: 2D Minkowski Spacetime Diagram Generator

I’m planning to write a 2D Minkowsky spacetime diagram generator tool. At this point, I am looking for help reviewing the specification. I am not looking for help with the implemenation. To be clear, I’ve written a complete specification, but it would be a waste if it was missing features that...
5. ### B Understanding Spacetime Diagrams from "Reality is not What it Seems

I'm reading a book called "Reality is not what it seems: the journey to quantum gravity" by Carlo Rovelli and I'm struggling to understand this diagram that is part of the chapter about special relativity. https://i.stack.imgur.com/JgBDJ.jpg Before this image Rovelli writes: "It's not...
6. ### I Alcubierre Warp Drive: Spacetime Diagram Explained

https://scipost.org/SciPostPhysLectNotes.10/pdf "Space expands behind the warp bubble and contracts in front of it, thus pushing the bubble forward at velocity v. The ship, which is at rest inside the bubble, moves along with the bubble at an arbitrarily large global velocity." If the ship...
7. ### Lorentz contraction and Spacetime diagram

Hello, i can't understand how does the author found this expression relating ##x_{c}## and v. I already tried by a lot of geometrical ways, knowing that the tangent of the angle between the dotted line and the x-axis should be v, but the results are illogical. Could you help me? I am start to...
8. ### Can someone help me interpret this spacetime diagram?

My question in specific is understanding what this line EB exactly represents. This was borrowed from the book "A first course in general relativity" by Schutz. There is a question on page 30 (number 12) which asks the following: "Use the fact that the tangent to the hyperbola DB in Fig. 1.14 is...
9. ### B Any interest in a spacetime diagram generator?

Hi, I've written a script-based spacetime diagram generator. I have no idea if it has any value for anyone besides myself—you may have access to better tools than I do. When I looked for spacetime generators, I only found some very limited web tools and one downloadable program that wasn't much...
10. ### I Exploring Simultaneity in Spacetime Diagrams - A.P. French, 1968

The images have been taken from page no.74,75 and 76, special relativity , A.P.French,1968 I understood that A1' and C1' are not simultaneous in S -frame. But I don't understand the principle on whose basis it is claimed that A1' and C1' are simultaneous in S' -frame. Here, the simultaneity is...
11. ### I Lines of simultaneity in Twin Paradox spacetime diagram

I set up a Twin Paradox scenario and accompanying spacetime diagram to help better understand the resolution, but I had a question about the diagram I was hoping someone here could help answer. Please excuse the hastily drawn diagram! (Note: the ' frame corresponds to the outbound trip, the...
12. ### Spacetime diagram for black hole

Homework Statement Consider a 2D spacetime with: ## ds^2 = g_{tt}dt^2 + g_{tx}(dtdx + dxdt)## where: ##g_{tt} = -x## and ##g_{tx}=3## Draw a spacetime diagram showing the null geodesics, including one which passes through the origin. Then show that for a massive object, when ##x## is positive...
13. ### Spacetime diagram drawing problem

I was drawing a spacetime diagram to relate Doppler shift effect but i stuck at a point which i can't understand This is what I'm trying to draw An object with mirror is moving away from me with a velocity of 50% speed of light When each second passes in my clock i send light pulses at that...
14. ### Solving Spacetime Diagram Homework: Ship Reversal from Cape Canaveral

Homework Statement At time t = 0, a spaceship leaves Cape Canaveral (x = 0) at speed 2/3c, heading directly upwards (+x direction) toward a satellite in orbit. The satellite is located a distance 2 AU (see footnote2 if you forget what that is) above the earth’s surface. When the ship...
15. ### Spacetime diagram - Twin paradox

I was studying the twin paradox (of Einstein special relativity) and everything was working well until I get to the traveler's spacetime diagram. First let me introduce the paradox for you to understand the diagram. Pam is the twin sister of Joe. Pam goes out Earth in 2007 in a spaceship...
16. ### Spacetime diagram based question.

Homework Statement A Spaceship is moving with speed ß=4/5. Its length at rest is 1sec. A light is turned on at the rear of the ship, reflected back from a mirror at the front. a.) How long does an observer at rest say it takes for the light to return to the rear of the ship (total round...
17. ### Spacetime diagram problem (spacelike intervals)

Homework Statement Suppose on a spacetime diagram, an event happens at x=-4, t=5 and another event happens at x=0 and t=6. If there is a frame such that the two events happen simultaneously, what would the relative speed of that frame be? Homework Equations The Attempt at a...
18. ### Creating Spacetime Diagrams with Math Software

Is there any software or program which can plot spacetime diagrams which includes worldlines, hyperbolas, etc. given some inputs? If not. Why is there none when spacetime diagrams are very useful?
19. ### On the interpretation of a spacetime diagram

Below is a spacetime diagram which depicts the movement of a rod, four units long, relative to another rod of equal length. The red lines are the "moving" rod; the purple lines are the "stationary" rod. The gray lines are the world lines of the unit marks (0, 1, 2, 3, 4) on each rod. As I...
20. ### Spacetime Diagram: Velocity Relative to Earth/Ship

Homework Statement To draw a carefully labelled spacetime diagram for the following situation: The addition of velocities as viewed from a ship, for the case of a missile launched at v_{mi}=+0.80c relative to the ship, itself traveling at v_{s}=+0.60c[/itex] relative to the Earth. Take the...
21. ### How to draw a spacetime diagram

here is my poor effort at teaching newbies how to draw spacetime diagrams (somebody has to do it): first draw your x axis. this represents space. (one dimension of it anyway. one dimension is enough for most thought experiments) the y-axis represents time. imagine there is a stationary...
22. ### Spacetime diagram grid area

I have an interesting finding in spacetime diagram - The area of the square grid for the rest frame O, is the same as the area of the rhombus grid for the inertial frame O'. More specifically, the area of the square for frame O (0, 0), (0, 1), (1, 1) and (1, 0) is 1 The area for the...
23. ### Sticky for beginners to draw a spacetime diagram

I'm always sending beginners to that post and it often answers their question. maybe we should have a sticky listing these equations. maybe throw in something about how to draw a spacetime diagram too. and a note about the lines of simultaneity being different for observers moving at...
24. ### Is the Loedel Diagram a Special Case of the Minkowski Spacetime Diagram?

The main attraction of the Loedel spacetime diagram is that it treats the reference frame and the first moving frame symmetrically and hence they have identical scales in geometric units. The Minkowski diagram uses different scales for the orthogonal and the non-orthogonal axes, where the time...
25. ### Deriving Doppler Shift Using Spacetime Diagram

Alright, I'm trying to derive the dopper shift using a spacetime diagram (see attached). If we model light pulses then we can derive the distance between the pulses in time, and hence the doppler shift... right? So, if we make some light pulses along some sort of time event in the x, cT frame...
26. ### Check Spacetime Diagram for Scenario w/v=3/4c & \gamma=1.5

I would apprecite it if someone could please check my spacetime diagram for the following scenario. I appreciate any help. I'm tutoring myself based on texts and have no instructor to ask. Scenario: S frame of reference with S' superimposed. S' is moving at velocity v=3/4 c in the +x...