Explaining 4D Space-Time in Simple Terms

In summary, 4D space-time is a concept in physics that combines the three dimensions of space with the dimension of time. An event, which is a point in space at a given time, is represented by a set of four numbers (t, x, y, z). This concept is often illustrated with the example of locating an appointment in a building using three coordinates for space and one for time.
  • #1
Omid
182
0
Can anyone explain 4D space-time in a simple form ?
Some say the Hawking's expalanation is the simplest but I don't get it :biggrin:
 
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  • #2
Omid said:
Can anyone explain 4D space-time in a simple form ?
Some say the Hawking's expalanation is the simplest but I don't get it :biggrin:
Sure. It takes 3 numbers to locate of an event in space - represent that as (x, y, z). The collection of all triplets (x , y, z) is called "space". It takes 1 number to specify the time of an event, t. Collect those two numbers into one set of numbers (t, x, y, z). That is called an "event". And event is a point in space at a given time. The collection of events (t, x, y, z) is called "spacetime".

Pete
 
  • #3
Can you give me some examples ?
Thanks
 
  • #4
I know this example has probably been beaten to death by numerous layman physics books, but it is very simple and it works to illustrate the concept of spacetime. Let's say you have an appointment in a particular office located in a particular building, which itself located at a particular street junction. To get to your appointment, you have to know three coordinates for space (the x and y coordinates are used to locate the building, while the z coordinate is used to locate which floor the office in the building is located.) And one coordinate for time (the time the appointment takes place.) Simple, no?
 
  • #5
Yes.
Thank you.
 
  • #6
Omid said:
Can you give me some examples ?
Thanks
One example is the same as the other. What you're asking is analogous to asking us for an example of space. Can you give me an example of space?

Pete
 
  • #7
Gza said:
I know this example has probably been beaten to death by numerous layman physics books, but it is very simple and it works to illustrate the concept of spacetime. Let's say you have an appointment in a particular office located in a particular building, which itself located at a particular street junction. To get to your appointment, you have to know three coordinates for space (the x and y coordinates are used to locate the building, while the z coordinate is used to locate which floor the office in the building is located.) And one coordinate for time (the time the appointment takes place.) Simple, no?

That is an example of an event. Not an example of spacetime.

Pete
 
  • #8
pmb_phy said:
That is an example of an event. Not an example of spacetime.

Pete

I don't care whether it is an event or an example of space time. :smile:
Because it is exactly what I meant. I don't know how GZA always gives me exactly the right thing.
Anyway, Pete, thank you very much.
 

1. What is 4D space-time?

4D space-time is a mathematical concept that describes the four dimensions of our universe: three dimensions of space (length, width, and height) and one dimension of time. It is often visualized as a four-dimensional grid or coordinate system, with each point representing a specific location in both space and time.

2. How is 4D space-time different from 3D space?

4D space-time includes the dimension of time, whereas 3D space does not. This means that in 4D space-time, an object's position is not only described by its location in space, but also by its position in time. This allows us to understand the movement and changes of objects in our universe.

3. How did the concept of 4D space-time come about?

The concept of 4D space-time was first introduced by Albert Einstein in his theory of general relativity. He proposed that space and time are not separate entities, but rather intertwined and affected by gravity. This led to the understanding that our universe can be described as a four-dimensional fabric, with matter and energy shaping its structure.

4. What are some examples of 4D space-time?

One example of 4D space-time is the motion of planets around the sun. This can be visualized as a three-dimensional orbit in space, with the fourth dimension being time. Another example is the bending of light around massive objects, such as stars, which can only be explained using the concept of 4D space-time.

5. Why is it important to understand 4D space-time?

Understanding 4D space-time is crucial in explaining the fundamental workings of our universe. It allows us to comprehend the behavior of objects in space, the effects of gravity, and the concept of time dilation. It also plays a key role in modern physics, including theories such as relativity and quantum mechanics.

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