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Can Absolute Velocity be Measured? 
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#1
Apr412, 05:26 PM

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Just a silly idea i have, please debunk it since i cannot figure it out:
The Thought Experiment: Provided to us is a spacecraft equipped with a particle acceleration and detection systems. The craft is set on a course where it would not be interrupted by any interstellar objects and cuts its propulsion systems for the entire duration of the experiment. A stream of electrons are accelerated to a certain speed (let’s say 0.8c) in the particle accelerator. The mass of an electron in the stream is then measured when the electron stream passes, say, in the direction the spacecraft is traveling. This measurement of electron mass when the electron stream passes in the direction the spacecraft is traveling is repeated for various speeds (0.82c, 0.84c, 0.86c, 0.88c and 0.9c). We then plot these values on a graph (e.g Figure 1). This graph represents the increase in mass of the electron at various velocities relative to the spacecraft. (Figure 1) The graph we obtained is then compared to the graph of: (Figure 2a) *9.10938215x1031 kg is the rest mass of an electron to see where it fits in. This can be achieved by comparing the change in gradients of both graphs. We then superimpose the graph we got (Figure 1) onto the graph of the equation of Figure 2a (Figure 3) We are now able to determine our velocity through spacetime in the direction the electron was traveling when it was measured by taking a point on the graph we obtained and subtracting the relative speed of the electron from its actual speed as reflected from the superimposed graph. Example: In Figure 1, we measure the relative speed of the electron, W, to be say 0.8c. When we superimpose the graph, the point which contains W now reads off the new graph as X (lets say 0.83c), so we deduce that we are moving through spacetime at a velocity of 0.03c in the direction the electrons were traveling when their mass was measured. This experiment is repeated where the mass of the electron is measured as it is traveling in various other directions to determine our absolute velocity through spacetime. The direction which yields the largest velocity will give us the absolute velocity of the spacecraft through spacetime. Further Applications The absolute velocity of the spacecraft through spacetime can be compared with the velocity of the spacecraft relative to the cosmic microwave background radiation (CMBR) reference frame. If both velocities are the same, we can assume that the CMBR reference frame (and the black hole/object that gave birth to big bang) is/was moving at an absolute velocity of 0 m/s through space. However, if both velocities were different, we can deduce that the CMBR reference frame (and the black hole/object that gave birth to big bang) is/was moving through space at a certain velocity. This comparison would shed some light on the physical nature of the big bang itself, allowing us to eliminate a few of the seemingly infinite number of theories that surrounds the beginning of the universe we know today. Thanks for reading! 


#2
Apr412, 05:33 PM

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P: 22,303

Welcome to PF!
Without reading your post, I can tell you this: the question posed in the title is misguided in that it assumes that there exists such a thing as absolute velocity. Current theory holds that there is no such thing, so it is meaningless/wrong to ask if it can be measured. 


#3
Apr412, 05:43 PM

P: 242

The experimental graph will always yield the graph of γm and nothing else, leading you to conclude a speed of zero every time, regardless of the spacecraft's velocity relative to other bodies.



#4
Apr412, 08:45 PM

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P: 4,087

Can Absolute Velocity be Measured?
Imagine a balloon, whose surface is a 2D space embedded in 3D. Now try to imagine that the surface is a 3D space embedded in 4D. Just as the surface area of a balloon of zero radius is zero, so the volume of the embedded 3D space was zero at tzero. 


#5
Apr512, 04:08 PM

P: 2

Thank you for your time and comments.
1. There is no such thing as absolute velocity? Maybe I am using the wrong term, but what would you define the velocity at which *God (an observer external to this universe)* measures you travelling at? If you accelerate (in your point of view) in one direction, time may pass slower for you but if you accelerate in another direction, time may pass faster for you as you are 'slowing down' in space. The point at which time dilation does not apply to you (except for gravitational time dilatation) can be considered a 'special' reference frame where absolute velocity and mass can be measured? 2. I know the most accepted theory holds that space and time exploded from the big bang, but I dun think that there is anything absolutely against space and time existing before the big bang. Spacetime could have been seen to have exploded out from the singularity as the singularity had sucked so much in to begin with. In any case, comparing 'absolute velocity' to the CMB reference frame would mean something either way. Dun want to argue too much about this. 3. ZikZak, would the experimental graph be the same? IMHO, One of the parameters in the equation is the rest mass of the electron measured relative to you. If you were travelling, you would weigh the electron rest mass to be more. The experimental graph you obtain should be of the same shape but translated away from the original graph. Thank again and have to GOOD Friday. 


#6
Apr512, 04:59 PM

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According to all known physics there is simply no such thing as absolute velocity  period; no qualifications or dancing around it. Any speculations otherwise should be pursued in a forum outside physicsforums (e.g. a religious forum). You are just throwing out purported observations that are contradicted by experiment, and by the most elemantary understanding of relativity. 


#7
Apr512, 05:01 PM

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P: 11,925

Note that different observers can measure different particle energys (and therefore different relativistic masses (I don't like this word)). Welcome to the concept of "relativity" ;). 


#8
Apr512, 09:35 PM

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#9
Apr612, 01:50 AM

P: 61

There is , of course, no such thing as absolute velocity.
An interesting thought, however, is a spinning cylinder in space and an observer flying past, parallel to it's spin with no acceleration. Everyone in the universe (even in an empty universe) will agree that the cylinder is spinning at x velocity. The observer can say "I am 5x away from it's moving point at an exact 180 degree angle...I am 4x away from it's moving point at an exact 180 degree angle...I am 3x....etc... Thus since it is moving with me and everybody agrees that it is moving, I am moving also." 


#10
Apr612, 07:30 AM

Math
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Thanks
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#11
Apr612, 07:39 AM

P: 61

" Everybody agrees that this accelerated point on the frame is moving, I am moving along the xaxis with it, thus I am moving. " 


#12
Apr612, 08:08 AM

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P: 6,353

Nicely put ! It's too bad some of the newbies don't get that before posting. 


#13
Apr612, 10:26 AM

P: 643

This is completely incorrect. Throw a ball straight up. At the peak of its toss, it is not moving. However, it is still subject to gravity, so it's still accelerating. Now, nothing can stay umoving for finite time when it's subject to acceleration. 


#14
Apr612, 10:39 AM

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#15
Apr812, 03:46 AM

P: 1,162

Based on an abstract dimensionless slice of time that does not apply to real world physics. Zeno's point in creating the paradox. On the other hand sitting motionless on the ground is a state of acceleration so you're right, not everyone agrees acceleration necessarily implies motion. 


#16
Apr812, 05:35 AM

P: 344

There is no absolute velocity, because c (and maybe everything else) always looks the same for all observers (so fare I have understood).
But this is not the same that there is no absolute motion direction. We can for example be moving the same or the opposite direction as the Milky Way, and at a larger perspective, the same or the opposite way as the local cluster, and if we one day will reach a larger perspective, for example multi universes moving relative to each other,  we can also be moving the same or opposite way relative to our Universe….etc.. I either cannot see the “problem” or any limit to that absolute motion not should exist. That out perspective is limited , cannot be the same that an absolute motion perspective not exist. 


#17
Apr812, 08:52 AM

P: 5,632

unsure just what you last post says....
but with Newtonian mechanics, the relative velocity is independent of the chosen inertial reference frame. Time and space are the same everywhere. All frames are the same. This is not the case anymore with special relativity in which velocities depend on the choice of reference frame. Time and distance vary in different partsof spacetime; any frame is as good as any other; different frames give different results. 


#18
Apr812, 09:44 AM

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