Would we as humans ever be able to travel close to the speed of light?

In summary, the conversation discusses the possibility of traveling close to the speed of light and the implications of doing so. It is mentioned that this technology is likely centuries in the future and that the method of propulsion may involve using something more efficient than converting mass to energy. Additionally, it is suggested that the interstellar medium could be used as a source of fuel. There is also a discussion about the effects of traveling at such high speeds and the potential for catching particles in space for fuel. It is ultimately concluded that the main purpose of traveling at the speed of light would be to distance oneself from Earth and that the effects of Lorentz contraction would only be noticeable to outside observers.
  • #1
zeromodz
246
0
I mean how would we ever do it in the first place? What rockets or propulsion units would we use?
 
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  • #2
It doesn't affect measurements you make in your own reference frame.
You wouldn't notice getting shorter, more massive, slower - only an outside observer would.
That's rather the whole point of relativity.
 
  • #3
mgb_phys said:
It doesn't affect measurements you make in your own reference frame.
You wouldn't notice getting shorter, more massive, slower - only an outside observer would.
That's rather the whole point of relativity.

The SR acceleration equations provide a different and impossible answer.

How much fuel is this? The next chart shows the amount of fuel needed (M) for every kilogramme of payload (m=1 kg).

d Not stopping, sailing past: M
4.3 ly Nearest star 10 kg
27 ly Vega 57 kg
30,000 ly Center of our galaxy 62 tonnes
2,000,000 ly Andromeda galaxy 4,100 tonnes
http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html
 
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  • #4
zeromodz said:
I mean how would we ever do it in the first place? What rockets or propulsion units would we use?
Well, it's untold centuries in the future, so the technology we'll use is going to be even weirder than anything we could dream of.

Ask a roman centurion how we will power our hybrid cars in the 21st century. (What's a hybrid car? What's a car?)
 
  • #5
But the Earth is already traveling at 0.99999999999c , so we are traveling close to the speed of light.
 
  • #6
cfrogue said:
How much fuel is this? The next chart shows the amount of fuel needed (M) for every kilogramme of payload (m=1 kg).

d Not stopping, sailing past: M
4.3 ly Nearest star 10 kg
27 ly Vega 57 kg
30,000 ly Center of our galaxy 62 tonnes
2,000,000 ly Andromeda galaxy 4,100 tonnes
Since there are no constraints on imagining how we do it, I would guess that, if/when we manage to do this, it will be by
a] not having to bring our fuel with us
b] using something more efficient than "primitive" total conversion of mass to energy.
 
  • #7
DaveC426913 said:
Since there are no constraints on imagining how we do it, I would guess that, if/when we manage to do this, it will be by
a] not having to bring our fuel with us
b] using something more efficient than "primitive" total conversion of mass to energy.

I vote for the no fuel option and pick up random particles in space, ...

lots of them.
 
  • #8
DaveC426913 said:
Since there are no constraints on imagining how we do it, I would guess that, if/when we manage to do this, it will be by
a] not having to bring our fuel with us
b] using something more efficient than "primitive" total conversion of mass to energy.

How silly of me.

Atyy already has this figured out.

We start out at 0.99999999999c and we do not need to worry about all this.

Sometimes, the answer can be so simple.
 
  • #9
cfrogue said:
How silly of me.

Atyy already has this figured out.

We start out at 0.99999999999c and we do not need to worry about all this.

Sometimes, the answer can be so simple.

OK, all seriousness aside, I'm pretty sure the point of pushing c is to get some distance from Earth.
 
  • #10
cfrogue said:
I vote for the no fuel option and pick up random particles in space, ...

lots of them.

Only problem with that is the interstellar medium is oh so sparse...you'd need a catching tool on the order of Astronomical units across just to get a few particles.

The interstellar medium is a much better vacuum than any vacuum we've ever been able to create on Earth.

I suppose you could just boost off each star system tho. Aim for one star system at a time, and bring enough fuel for ~10 Light-years of travel.
 
  • #11
Matterwave said:
Only problem with that is the interstellar medium is oh so sparse...you'd need a catching tool on the order of Astronomical units across just to get a few particles.

The interstellar medium is a much better vacuum than any vacuum we've ever been able to create on Earth.

I suppose you could just boost off each star system tho. Aim for one star system at a time, and bring enough fuel for ~10 Light-years of travel.

Fine then,.

I say drive by planets and whatever else and suck their mass.

I note I can buy the latest vacuum cleaners on TV and they are guaranteed..
 
  • #12
DaveC426913 said:
OK, all seriousness aside, I'm pretty sure the point of pushing c is to get some distance from Earth.

mgb-phys and I answered when the original question was: would traveling near the speed of light Lorentz contract our organs and kill us?
 
  • #13
In your own reference frame, nothing changes. You would see the universe around you contract though...that would be quite weird! =P
 
  • #14
atyy said:
mgb-phys and I answered when the original question was: would traveling near the speed of light Lorentz contract our organs and kill us?

You failed to consider the acceleration to get you there.

We have a recent thread on the Born issue about this.
 
  • #15
atyy said:
mgb-phys and I answered when the original question was: would traveling near the speed of light Lorentz contract our organs and kill us?

When was that the original question?
 
  • #16
atyy said:
mgb-phys and I answered when the original question was: would traveling near the speed of light Lorentz contract our organs and kill us?

The born thread shows our organs would expand during acceleration.
 
  • #17
cfrogue said:
The born thread shows our organs would expand during acceleration.
What??
 
  • #18
In case anybody doesn't know about this, see:

http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)

Orion spacecraft , which are actually possible to build today, can achieve 8-10% the speed of light using hydrogen bombs and 50-80% the speed of light using matter-antimatter annihilation. If it's possible to store antimatter, relativistic space travel is certainly possible.

BTW, Dave, did you just say "all seriousness aside"?
 
  • #19
DaveC426913 said:
What??

?
the born thread recently shows during acceleration, all expands in the accelerasting frame.
 
  • #20
DaveC426913 said:
When was that the original question?

Oh, I don't know. Maybe I was dreaming, but mgb_phys's answer makes much more sense if he also had the same dream. Anyway, it doesn't matter.
 
  • #21
cfrogue said:
?
the born thread recently shows during acceleration, all expands in the accelerasting frame.

Is English not your first language? That's not even a sentence.
 
  • #23
zeromodz said:
I mean how would we ever do it in the first place? What rockets or propulsion units would we use?

Not a very popular opinion in some quarters, but I believe that eventually humans will achieve everything that is theoretically possible. The laws of physics are our only limitations, all technologies required will eventuially become realities.

Matheinste.
 
  • #24
cfrogue said:
hear is the thred

https://www.physicsforums.com/showpost.php?p=2443198&postcount=36

please make sure you read ther paper

What are you telling me? That this thread is a continuation of that thread? Is that what you mean when you say "born thread"? Am I the only one here that did not know there was a previous thread?
 
  • #25
DaveC426913 said:
What are you telling me? That this thread is a continuation of that thread? Is that what you mean when you say "born thread"? Am I the only one here that did not know there was a previous thread?

No, I was telling you acceleration under SR expands the internal metrics of the accelerating frame.
 
  • #26
cfrogue said:
No, I was telling you acceleration under SR expands the internal metrics of the accelerating frame.

This makes no sense. SR is a theory that is devoid of accelerating reference frames, and only considers inertial reference frames, that's why it's Special. You mean GR?
 
  • #27
Matterwave said:
This makes no sense. SR is a theory that is devoid of accelerating reference frames, and only considers inertial reference frames, that's why it's Special. You mean GR?

What? SR can deal with acceleration - it's gravity that requires GR.

Maybe there are different understandings of 'frames' at play. One sense, just focus on an accelerating object - say a rocket ship - and ask how clocks and rods stationary with that rocket ship would behave. On another sense, 'frame' is short for 'inertial frame' - in which case, a frame can't be accelerating. Behaviour of objects in an accelerating rocket ship can be done within SR.

Of course, speed of light is not measured to be c, and the laws don't have the same form from the point of view of an accelerating frame. But SR alone will tell you that.
 

FAQ: Would we as humans ever be able to travel close to the speed of light?

1. How fast is the speed of light?

The speed of light is approximately 299,792,458 meters per second, or about 670 million miles per hour.

2. Can humans ever travel at the speed of light?

No, according to Einstein's theory of relativity, it is not possible for any object with mass to reach the speed of light. As an object approaches the speed of light, its mass increases infinitely and it would require an infinite amount of energy to reach that speed.

3. Why is traveling at the speed of light considered impossible?

Aside from the limitations of Einstein's theory of relativity, there are also practical and technical challenges that make traveling at the speed of light currently impossible. The energy required to propel an object to that speed is immense and our current propulsion technology is not advanced enough to achieve it.

4. Are there any theories or research being done to try to travel at the speed of light?

Yes, there are ongoing studies and research being conducted to explore the possibilities of near-light speed travel. Some proposed methods include using antimatter or harnessing the power of black holes. However, these are still in the theoretical stages and would require significant advancements in technology to become a reality.

5. What are the potential implications of traveling at the speed of light?

If it were possible to travel at the speed of light, it would revolutionize space exploration and transportation. It would significantly decrease travel time between distant locations in the universe and could potentially lead to new discoveries and advancements in science and technology. However, there are also potential risks and dangers associated with such high speeds, such as collisions with debris or radiation exposure.

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