Is this a way to move faster than c?

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SUMMARY

The discussion centers on the concept of galaxies moving away from Earth faster than the speed of light (c) due to the universe's expansion, quantified at approximately 77 km/sec per 3.26 million light years. Participants explore the implications of curved spacetime, emphasizing that velocities of distant galaxies cannot be directly compared to local velocities due to this curvature. The conversation highlights that while galaxies may appear to move faster than c, this is a result of the geometry of the universe, which complicates the notion of velocity comparison across vast distances.

PREREQUISITES
  • Understanding of general relativity and spacetime curvature
  • Familiarity with the concept of cosmic expansion and redshift
  • Basic knowledge of geodesics in curved spaces
  • Awareness of the limitations of measuring velocities in non-flat geometries
NEXT STEPS
  • Study the implications of general relativity on cosmic expansion
  • Learn about the concept of geodesics and their significance in curved spacetime
  • Research the effects of gravitational fields on spacetime curvature
  • Explore the mathematics of velocity in non-Euclidean geometries
USEFUL FOR

Astronomers, physicists, and students of cosmology interested in the complexities of cosmic velocities and the implications of general relativity on our understanding of the universe.

  • #121
From all this all I can gather is that in order to exceed the speed of light. time-space itself must expand. Again, it has never been shown that light speed cannot differ from 300 X 106 m/sec but nothing has shown that it does differ from that other than traveling through media.

Even if you think about it the searchlight paradigm fails. Think of a circular sprinkler system. The fastest any of the particles are moving laterally is the linear speed they had when they left the sprinkler.

Proper time doesn't add up either. At least I would like to see some simple mathematical model of how this could create transmission greater than light speed.

From Fiddler on the Roof there is an analogous situation explained: "If I were the Tsar, I would be richer than the Tsar!"
"How so?"
""I would have all the wealth and power of the Tsar, and...
.
.
.
.
.
I would do a little teaching on the side!"
 
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  • #122
I can not see that space is curved
 
  • #123
If we talk about how to moove faster then speed of light, then we must consider which law has given this restriction , If we prove that law to be wrong ( I mean if we prove special theory of relativity wrong) then it could be I have tried to proove that to know visit http://sallubhai007.blogspot.com
 
  • #124
sallubhai007 said:
I can not see that space is curved

That's because what your seeing isn't where you think it is.
 
  • #125
we can refer shape to only material thing like a ball and we can not refer shape to non-material things like electric field , magnetic field etc ,althou we know that they exist like that space is also a non-material thing then why we talk about its shape imean its curve
 
  • #126
So, what's the consensus? Appears that there is no proof that we can move faster than c (=300 million m/sec.) In fact, there is no proof that c is constant everywhere in this or another universe, just local to what we know.
 
  • #127
stevmg said:
So, what's the consensus? Appears that there is no proof that we can move faster than c (=300 million m/sec.) In fact, there is no proof that c is constant everywhere in this or another universe, just local to what we know.

According to general relativity (and ignoring the hypothetical, but very unlikely, possibility that tachyons might exist), nothing can overtake a photon that is traveling along the same route.

The numerical value of the speed of a photon depends on the coordinate system you measure it in. If you measure it locally, using a "local ruler" x and "local clock" t, you will always get dx/dt = c (=299792458 m/s exactly) no matter where you are in the Universe or how you are moving. But if you try to measure the speed of some light a distance away from yourself, you may well get a different numerical value. This is due to spacetime curvature. An analogy is that cartographers can accurately draw a scale map of an area a few miles across, but if you try to map a thousand miles of the Earth's surface on a flat piece of paper, the map could be very accurately to scale at the centre of the map, but distorted in angle or distance near the edges. This is what happens in relativity, long-distance measurements can get distorted.

As for the expanding Universe, the simple analogy is that of the surface of an expanding balloon. The balloon expands so fast that speed-of-light signals from distant parts never get to reach us, as the cumulative expansion over very large distances is effectively "faster than light". What I said in the previous paragraph still holds, though.
 
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  • #128
DrGreg said:
What I said in the previous paragraph still holds, though.


Would it be accurate to relate the curve of the balloon to the curvature of space? If we look back at the idea of the map maker trying to make a distant object on the Earth, would the expanding of space be like the Earth was growing/inflating while he was doing so?
 
  • #129
Bussani said:
Would it be accurate to relate the curve of the balloon to the curvature of space? If we look back at the idea of the map maker trying to make a distant object on the Earth, would the expanding of space be like the Earth was growing/inflating while he was doing so?
The two analogies I gave aren't really directly comparable. The "map of Earth" analogy is referring to spacetime, whereas the "expanding balloon" is referring to space. You can only take these analogies so far.
 
  • #130
DrGreg said:
According to general relativity (and ignoring the hypothetical, but very unlikely, possibility that tachyons might exist), nothing can overtake a photon that is traveling along the same route.

The numerical value of the speed of a photon depends on the coordinate system you measure it in. If you measure it locally, using a "local ruler" x and "local clock" t, you will always get dx/dt = c (=299792458 m/s exactly) no matter where you are in the Universe or how you are moving. But if you try to measure the speed of some light a distance away from yourself, you may well get a different numerical value. This is due to spacetime curvature. An analogy is that cartographers can accurately draw a scale map of an area a few miles across, but if you try to map a thousand miles of the Earth's surface on a flat piece of paper, the map could be very accurately to scale at the centre of the map, but distorted in angle or distance near the edges. This is what happens in relativity, long-distance measurements can get distorted.

As for the expanding Universe, the simple analogy is that of the surface of an expanding balloon. The balloon expands so fast that speed-of-light signals from distant parts never get to reach us, as the cumulative expansion over very large distances is effectively "faster than light". What I said in the previous paragraph still holds, though.


I like this answer the best. It combines what we DO know with what we don't and makes intuitive sense. Of course, SR and GR and all FR whatever references may just be part of a greater reality which we don't know just as Newton was part of the greater reality of relativity but who knows?
 
  • #131
DrGreg said:
The two analogies I gave aren't really directly comparable. The "map of Earth" analogy is referring to spacetime, whereas the "expanding balloon" is referring to space. You can only take these analogies so far.


Gotcha. Thanks.
 
  • #132
no object can travel faster than light because keeps increasing as we approach velocity of light beyond the speed of 0.999 c the mass becomes infinite so your appartus won't work galaxy are not moving faster than light the space which they are associated is expanding at unbelievable velocity relativity puts no constraint upon how fast the space could expands this is the reason why we the deep space is 42 billion light year deep atleast we can see this deep and universe is only 15 billion year old so the furthest we could see should be 15 bn not 42 and more.and such movement of space is the basis of FTL system like alcuiberre warp drive and slip string warp drive.no law breaks since matter is not traveling at the speed of light nor and information carrying signal only space is.sorry for getting a bit off topic
 
  • #133
kai0 said:
no object can travel faster than light because keeps increasing as we approach velocity of light beyond the speed of 0.999 c the mass becomes infinite so your appartus won't work galaxy are not moving faster than light the space which they are associated is expanding at unbelievable velocity relativity puts no constraint upon how fast the space could expands this is the reason why we the deep space is 42 billion light year deep atleast we can see this deep and universe is only 15 billion year old so the furthest we could see should be 15 bn not 42 and more.and such movement of space is the basis of FTL system like alcuiberre warp drive and slip string warp drive.no law breaks since matter is not traveling at the speed of light nor and information carrying signal only space is.sorry for getting a bit off topic

Would you please rewrite that?
 
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