Superluminary travel at present

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In summary, the expansion of the universe allows for objects to move away from us at speeds greater than the speed of light, but this does not mean they are no longer visible to us. Objects that are currently outside the Hubble radius can still send light that will eventually reach us, and this was especially true in the past. This is due to the decreasing Hubble parameter and the increasing Hubble radius. Therefore, it is possible for objects that were receding at superluminal speeds when they emitted light to still be visible to us.
  • #1
poeteye
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Is there a part of today's observable universe that is traveling away from us at faster than light speed? (relatively speaking, of course) Is the known universe large enough for a cumulative expansion rate to exceed light speed?
 
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  • #2
Anything going faster than the speed of light relative to us (due to expansion) is no longer visible, since the light can't get here. Current theory has this happening.
 
  • #3
poeteye said:
Is there a part of today's observable universe that is traveling away from us at faster than light speed? (relatively speaking, of course) Is the known universe large enough for a cumulative expansion rate to exceed light speed?

If you mean velocity through space the answer is no, due to the Lorentian transformation of special relativity. If you mean the general-relativitistic Hubble velocity of expanding space the answer is yes. The Hubble velocity of expanding space is not restrained by the Lorentian transformation of special relativity.
 
  • #4
mathman said:
Anything going faster than the speed of light relative to us (due to expansion) is no longer visible, since the light can't get here. Current theory has this happening.

In an expanding universe, a photon that is emitted from an atom toward an observer not only travels through its local space at the speed of light but the photon also rides on the Hubble flow velocity (relative to the source) of its local space. Therefore, barring absorption by intervening atoms the photon will eventually reach the observer even if the relative Hubble flow velocity of the source (i. e. velocity relative to the observer) is greater than the speed of light.
 
  • #5
Therefore, the text of my poem below would be an accurate assessment?SUPERLUMINELLE

The Universe is expanding,
Faster than the limit of light,
Beyond common understanding.

Cosmology is demanding.
Its study is by no means slight.
The Universe is expanding.

There are heroes quite outstanding
Who apply their full mental might
Beyond common understanding.

There
 
  • #6
The reason I ask is that I received a critique on the post below, telling me that I was inaccurate about the universe expanding faster than light. From your answers, I feel justified and that my interpretation is correct. Thank you. If you would like to check for yourself and comment, please go to
http://www.lit.org/view/41024
 
  • #7
poeteye said:
The reason I ask is that I received a critique on the post below, telling me that I was inaccurate about the universe expanding faster than light. From your answers, I feel justified and that my interpretation is correct. Thank you. If you would like to check for yourself and comment, please go to
http://www.lit.org/view/41024

I liked reading the whole poem where you linked to. The villanelle form is a lovely tight form, I hope you write more. I think Dylan Thomas wrote a villanelle (Do not go gentle). The poem's name Superluminelle is also witty. I hope you come around here more and ask physics and cosmology questions.

poeteye said:
Is there a part of today's observable universe that is traveling away from us at faster than light speed? (relatively speaking, of course) Is the known universe large enough for a cumulative expansion rate to exceed light speed?

Most of the objects which are observable to us in the sense that their light is now reaching us were receding at speeds greater than c when they emitted the light that is now arriving.

General Relativity pretty much forces superluminal expansion (by way of the Friedmann equation model derived from it---IOW standard cosmology.) The special relativity limit does not apply to the speeds that distances expand.

mathman said:
Anything going faster than the speed of light relative to us (due to expansion) is no longer visible, since the light can't get here..

This is a false statement. The Hubble parameter is still decreasing (even though a''(t) is positive due to Lambda) and therefore the Hubble radius is increasing. An object which is today just outside the Hubble radius CAN send us light today which will eventually reach us. Objects which are currently between 14 and 16 billion LY from us ARE receding at >c and nevertheless CAN send light today which will reach us.

This effect was more remarkable in the past. For example the atoms which emitted the CMB light which we are now receiving were receding at over 60c (sixty times the speed of light) when they emitted the light that we are now getting.

And they are now receding at about 3.3c. So clearly we can see some things which were receding superluminal when they sent the light, and which are now receding superluminal. That one example illustrates it. But actually that is typical. Most of the universe that we now observe, volumewise, was receding superluminal when the objects emitted the light we are now getting.
 
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  • #8
So, the farther back we go to the fastest moving cosmos, the fastest we can see go 60c?
 

What is superluminary travel?

Superluminary travel is a theoretical concept in which objects can travel faster than the speed of light. It is also known as faster-than-light (FTL) travel.

Is superluminary travel possible?

Currently, there is no scientific evidence or technology that supports the possibility of superluminary travel. It goes against the laws of physics as we currently understand them.

What is the theory behind superluminary travel?

The theory behind superluminary travel is based on the idea of manipulating space-time to create a shortcut between two points, allowing an object to travel faster than the speed of light without violating the laws of physics. This is known as the Alcubierre drive.

What are the potential benefits of superluminary travel?

If it were possible, superluminary travel could revolutionize space exploration and allow us to reach distant galaxies and planets in a much shorter amount of time. It could also have practical applications in long-distance communication and transportation.

What are the potential dangers of superluminary travel?

If superluminary travel were possible, it could have serious consequences for the laws of physics and our understanding of the universe. It could also have unintended effects on space-time and cause disruptions in the fabric of the universe. Additionally, the energy required for superluminary travel would be immense and potentially dangerous.

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