Total velocity of resting object on earth from universal frame of refe

Click For Summary

Discussion Overview

The discussion revolves around calculating the total velocity of an object at rest on Earth from the perspective of the observable universe. Participants explore the implications of various frames of reference, including the Earth's rotation, its orbit around the Sun, the Sun's movement within the galaxy, and the galaxy's motion in the universe, while considering special relativity (SR) and the complexities of cosmological motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant calculates the total velocity of an object on Earth using normal vector addition, arriving at 3,000,900 km/hr, and then applies a relativistic velocity formula, yielding a slightly different result of 3,000,895.06594378 km/hr.
  • Another participant notes that simply adding speeds results in a greater sum than using the relativistic formula, suggesting that the difference in results is expected.
  • There is a discussion about the significance of the calculated value, with some participants questioning its relevance and others asserting that it is an interesting exercise.
  • Concerns are raised about the appropriateness of applying special relativity to this problem, given the involvement of gravity and the expanding universe.
  • One participant expresses a desire to visualize and understand the calculations for artistic purposes, while seeking clarity on the validity of their approach.
  • Questions arise regarding the accuracy of existing values for the solar system's velocity within the galaxy and whether they account for redshift and cosmic expansion.
  • There is a debate about the applicability of special relativity in different frames of reference, particularly when transitioning from the galaxy frame to the universe frame.

Areas of Agreement / Disagreement

Participants generally do not reach a consensus on the significance of the calculations or the appropriateness of using special relativity for this context. Multiple competing views remain regarding the validity and relevance of the calculations and the implications of different frames of reference.

Contextual Notes

Participants acknowledge limitations in their calculations due to assumptions about velocities and the complexities introduced by gravity and cosmic expansion. There is also uncertainty regarding the applicability of special relativity in cosmological contexts.

Who May Find This Useful

Individuals interested in the intersection of physics and art, those exploring concepts of motion in a cosmological context, and participants curious about the implications of different frames of reference in physics may find this discussion useful.

cyboman
Messages
250
Reaction score
45
I'm interested in calculating the total velocity of an object on Earth from the farthest frame of reference (the observable universe). I apologize that I am not a physics or science major so please bare with me.

I've posted on another google forum and was told a few different ideas.

Initially I used normal vector addition to add the velocities of the rotation of the earth, the orbit around the sun, the movement of the sun in the galaxy, and then the movement of the galaxy in the universe. When I do that with the numbers I have I get:

3 000 900 km/hr.


I've tried adding the velocities using the formula linked to for special relativity
u + v
w = ---------
1 + uv/c2

and I got this:

3000895.06594378 km/hr

which is -4.93405622430146 km/hr difference than the normal vector addition I performed before to get: 3 000 900 km/hr.

Does that sound right?

Basically If a ball was rolling on a table at a certain velocity on earth, I would like to know the total velocity it is moving taking into account ALL of the cosmological motion it exists within (also taking into account SR). Does this question have a quantifiable value?

Thanks for your time.

-cybo
 
Physics news on Phys.org
cyboman said:
I'm interested in calculating the total velocity of an object on Earth from the farthest frame of reference (the observable universe). I apologize that I am not a physics or science major so please bare with me.

I've posted on another google forum and was told a few different ideas.

Initially I used normal vector addition to add the velocities of the rotation of the earth, the orbit around the sun, the movement of the sun in the galaxy, and then the movement of the galaxy in the universe. When I do that with the numbers I have I get:

3 000 900 km/hr.


I've tried adding the velocities using the formula linked to for special relativity
u + v
w = ---------
1 + uv/c2

and I got this:

3000895.06594378 km/hr

which is -4.93405622430146 km/hr difference than the normal vector addition I performed before to get: 3 000 900 km/hr.

Does that sound right?
If you simply add together a bunch of speeds, you will get a greater sum than when you use the relativistic velocity formula, so yes, that sounds right.
cyboman said:
Basically If a ball was rolling on a table at a certain velocity on earth, I would like to know the total velocity it is moving taking into account ALL of the cosmological motion it exists within (also taking into account SR). Does this question have a quantifiable value?
Not really. Certainly you can calculate a value based on your assumptions of how fast each thing is moving relative to the next thing but finally you will run out of things with a measurable speed difference.
cyboman said:
Thanks for your time.

-cybo
You're welcome, and welcome to the Physics Forums.
 
ghwellsjr said:
Not really. Certainly you can calculate a value based on your assumptions of how fast each thing is moving relative to the next thing but finally you will run out of things with a measurable speed difference.

Thanks for your reply. So for the values that do exist (those which I was able to google), the value is accurate as far as they are?

And since I was able to find a value for the movement of our galaxy (which I assume is approximate) within the universe; the farthest frame of reference that is quantifiable would be floating outside our galaxy (assuming no other motion or forces are acting on that frame)?

Therefore, at rest an object on Earth is roughly moving at 3 million km/hr (according to my data) from that "intergalactic" frame?

Thanks for your time!

-cybo
 
cyboman said:
Thanks for your reply. So for the values that do exist (those which I was able to google), the value is accurate as far as they are?
I'm only saying the calculation is accurate. I'm not saying it is a significant calculation to be interested in making. Why does it interest you?
cyboman said:
And since I was able to find a value for the movement of our galaxy (which I assume is approximate) within the universe; the farthest frame of reference that is quantifiable would be floating outside our galaxy (assuming no other motion or forces are acting on that frame)?

Therefore, at rest an object on Earth is roughly moving at 3 million km/hr (according to my data) from that "intergalactic" frame?

Thanks for your time!

-cybo
As long as you realize that the "intergalactic" frame is no more significant than the "solar system" frame or the "earth" frame or the "Jupiter" frame or any other frame moving with any speed short of light speed in any direction with respect to any of those other frames.
 
ghwellsjr said:
I'm only saying the calculation is accurate. I'm not saying it is a significant calculation to be interested in making. Why does it interest you?

I have a friend out there. Hehe, j/j. I'm interested in calculating this value simply because it represents the farthest calculable frame of reference for Earth based motion. I'm an artist and programmer and I find the visualization and math intriguing.
ghwellsjr said:
As long as you realize that the "intergalactic" frame is no more significant than the "solar system" frame or the "earth" frame or the "Jupiter" frame or any other frame moving with any speed short of light speed in any direction with respect to any of those other frames.

Absolutely, I'm not favoring or singling out the "intergalactic" frame as special. I'm interested in that frame since it is so far. We don't know the motion of our universe in whatever it is that exists outside of it, or whether it is at motion at all. So as I understand it the "intergalactic" frame is farthest measurable frame with actual velocities to add. Is this mode of thinking flawed?

Thanks for your time George.

-cybo
 
Last edited:
cyboman said:
I have a friend out there. Hehe, j/j. I'm interested in calculating this value simply because it represents the farthest calculable frame of reference for Earth based motion. I'm an artist and programmer and I find the visualization and math intriguing.

Absolutely, I'm not favoring or singling out the "intergalactic" frame as special. I'm interested in that frame since it is so far. We don't know the motion of our universe in whatever it is that exists outside of it, or whether it is at motion at all. So as I understand it the "intergalactic" frame is farthest measurable frame with actual velocities to add. Is this mode of thinking flawed?

Thanks for your time George.

-cybo
It's flawed in the sense that you are using a Special Relativity application (relativistic velocity addition) to "solve" a problem that also involves gravity and an expanding universe where SR no longer applies. But if it is for artistic purposes, you are allowed license, right?.
 
ghwellsjr said:
It's flawed in the sense that you are using a Special Relativity application (relativistic velocity addition) to "solve" a problem that also involves gravity and an expanding universe where SR no longer applies. But if it is for artistic purposes, you are allowed license, right?.

Is this problem too complex for someone like myself to calculate? What sort of calculations are needed to get an accurate number?

Do the values that exist say for the velocity of our solar system within the galaxy not take into account red-shift / expansion? I would of assumed they needed the doppler CBR stuff to even come up with that number no?

It seems to me the velocites can be added with SR accurately to the point of our galaxy frame. It is when we try to jump outside that frame into the frame of the universe where it becomes meaningless to use SR. Is this correct? or is SR meaningless in all frames?

I of course am allowed to show whatever I like. But for the sake of my own interest and the project I would like to get the numbers as accurate as possible. I need not understand all the math or physics but I would like to perform those calculations. Is this not possible to any degree? I don't mind stepping back a frame and only calculating within the Milky Way frame of reference.

The time article here states all the relevant velocities: (they may be a bit different than my previous data) and speaks of new data showing the velocity of the Solar system is actually less than previously thought. Are these values not taking into account the other forces you speak of?

http://www.time.com/time/health/article/0,8599,2114544,00.html

Thanks again for your continued feedback.

-cybo
 
Last edited:

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 19 ·
Replies
19
Views
4K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K