# Self relative light speed is infinite

1. Dec 27, 2004

### DJmaux

I would like to talk about the speed of light and how so many people, even physicists, dont realise that light speed relative to its self is in fact infinite.
What I mean by this is if you travel at light speed you in fact travel at infinite velocity, not 300,000 km/s.
Is there any one here who realises this?
I see so many people talk about is it possibile to travel faster than light or I see on space ship programs on tv "faster than light engines" etc and its all a load of rubbish!

I will explain why this is. As you travel faster and start to get close to the speed of light what happens is everything around your ship starts to have severe time dialation. For example you could be in a ship and travel at close to light speed for a year and when you came back to earth 100 years could of passed.
Now this means that as you get closer to light, everything around you moves faster and faster including the light so if you were traveling at say
299,990 KM/S relative to someone watching you on earth, the light photon and your space ship would be traveling at something like 1,000,000,000,000,000 KM/S relative to you and the light.
If there was a camera on the ship and people on earth saw you talk,
you would appear to be talking 1,000,000s of times more slowly just as if the person on the ship could see you on earth he would see you talking 1,000,000's of times more quickly.

Now as you actualy hit light speed and people on earth see you doing 300,000 KM/S you are in fact traveling at infinite velocity, not 300,000 kms.
You would arrive at your destination instantly thus you cannot travel faster that light because its traveling infinitly quickly relative to its self or any one traveling at that speed.

This is why it takes infinite energy to reach light speed.
Why would it take infinite energy to reach 300,000 KM/S??? It wouldnt.
It takes infinite energy because you would be traveling at infinite velocity.
The thing is though if you hit light speed/infinite velocity time would pass infinitly quickly outside the ship and so the universe would probabably colapse or something before you ever reached light speed so I guess its impossible.

But i just wonder why so many people havnt worked this one out ????

2. Dec 28, 2004

### StatusX

What you're refering to is called proper velocity, that is, the distance you travel measured in the external, "stationary" frame, divided by the time in your own frame. It is true that this can be arbitrarily high. This isn't news to any decent physicist, and I'm sure many high school students have already "worked this one out". As no observer can travel at light speed, it is meaningless to say that time passes infinitely fast when you do. Don't forget, it takes light about 8 minutes to reach us from the sun, and millions of years to reach other galaxies, so it hardly travels infinitely fast.

Last edited: Dec 28, 2004
3. Dec 28, 2004

### DJmaux

You say it takes 8 minuites to reach from the sun or millions of years from other galaxys but if you say that you didnt read what I said properly.
Yes relative to us light travels at 300,000 km/s so yes we see the light take 8 minuites to reach the sun but for the light it takes no time at all or for any one traveling at that speed. If you travel to the sun at light speed anyone watching you would see you take 8 minuites to get there and if the was a camera on the ship and they saw you stood in your ship you would be absolutly motionless the whole journy and for you, you would get the instantly because light speed relative to its self is infinite even though relative to us it isnt. You follow?

4. Dec 28, 2004

### DJmaux

Oh BTW I think I made one error. My saying the universe would end if you travel light speed is wrong. If (relative to us) you traveled to the sun at light speed what would happen is the 8 minuites would pass instantly.

5. Dec 28, 2004

### StatusX

This should really be on a physics board. First, nothing that could be called an observer could travel light speed, so you should only speak of it as a limit. For example, you can get to a speed where people who observe you see your time passing as slowly as you want, but you can never get to a point where time stops.

The reason your proper velocity can get arbitrarily high is because of length contraction, not time dilation. As you travel faster and faster, external meter sticks get shorter and shorter. Now, according to your own, onboard meter sticks, which haven't shrunk, you will always be travelling slower than 300,000 km/sec. But if you use the external meter sticks, which is basically all your suggesting, then you can get a value much higher. The only possible philosophical consequence of this is that, theoretically, to photons, there is no such thing as space or time. Due to infinite contraction, their start and destination are at the same place, and it takes no time to make the trip. But I don't see any important insights coming from this fact.

6. Dec 29, 2004

### DJmaux

Yes that right! There is an infinite contraction of the universe as you hit light speed so that the universe becomes an infinitly small point thus it takes no time to get somewhere.
Sorry I just thought this post was worthwhile as so many people think that you cant go faster than light in that its impossible to travel say 1000 light years in less that 1000 years realative to your self. I just thought it was worth while becase it means you can get to other solar systems/galaxys in much less time than that.

7. Dec 31, 2004

The philosophical consequence of your inquiry is that there would not seem to be the experience of existence if physical objects traveled at light speed, it is only because we travel at slower speeds relative to light that we experience its effects.

We can measure a light beam traveling to the moon and back in 3 seconds but if we would be that light beam, it would be 3 seconds to the moon or to transverse the universe.

8. Dec 31, 2004

### loseyourname

Staff Emeritus
It's kind of meaningless to say that, though. Let's say, for the sake of argument, that a space vessel could travel at light speed. Because it would not experience time, it could not ever have a change of state; that is, it couldn't stop and the occupants of the vessel could never do anything. It really isn't a feasible idea of travel. To an outside observer, you'd eventually get somewhere, but you'd cease to even have your own point of view, as your sensory system would no longer function without time.

9. Dec 31, 2004

### Erazman

why would you want your sensory system to function

10. Jan 1, 2005

### loseyourname

Staff Emeritus
None of your systems would function. You'd want them to function because if they don't function, you're not alive. It's hardly sensible to take a trip for the sake of speed when the speed kills you.

11. Jan 1, 2005

If you exchange the space vessel and its occupants with photons we have quite a paradox on hand. What type of a sensory system could a photon have, to casually do what it does, in no time frame, for the physical world to evolve the way it does? The physical world would make no sense; the second law of thermodynamics would have no casual link to photon interaction.

12. Jan 1, 2005

### StatusX

Like I said, for objects with mass, the speed of light is a limit. You can get to a speed where your time passes (in the eyes of outside observers) arbitrarily slowly, but never to a point where it stops. Also, you can go fast enough so that the galaxy shrinks so much in your direction of motion that you can cross it in a few seconds. However, thousands of years will have passed to everyone else during this trip. This is theoretically possible, but probably will never be practical. For one thing, it would probably take the energy of several stars. And even if we ever could provide that energy, it might be physically impossible because the ship would warp spacetime so significantly it would probably form a black hole and be destroyed at some speed.

13. Jan 1, 2005

### DJmaux

Yes I mean obviously traveling a light speed will never be an option because either the moment you hit light speed you would crash into the edge of the universe and your ship would blow up.
Or (and im not sure about this) I think once you hit light speed the universe becomes a single point (singularity) and you end up occupying every point in the entire universe.
I dont really know how that works as I dont know much about it but am I right in assuming that because the universe shrinks the ship grows bigger?
I know that as you travel faster your mass increases but isnt that because the ship grows in size because the universe is shrinking to you?
If thats the case then once you hit a certain speed your ship would crash into suns/planets etc
Any way like I said we arnt going to travel light speed or anywhere close but it still means that if we can get up a fair speed we get to where we want to go faster than it should take. I guess the question is can we ever find an infiinte energy souce like zero point energy/black hole engines etc.
My guess is we will although the potential danger in making engines with infinite power could be very severe!
Anyway we wouldnt find an awful lot by exploring other galaxys etc because all the races that are more advaced than us have trancended to higher dimensions and are waiting for us to evolve more before they meet us.

14. Jan 1, 2005

http://www.fourmilab.ch/cship/cship.html

15. Jan 1, 2005

### DJmaux

Yes your site basicly shows how self relative light speed is infinite as it shows you can travel 17,000,000,000 light years in 5 years at near light speed but 17,000,000,000 years would pass on earth.
Also interesting it says the universe only shrinks along the line of travel so the universe wouldnt shrink to a point but it would become completly flat or 2D.
It would have height and width but no length.
I guess this shows you the universe is an illusion and isnt really of any size at all or more acuratly the size of the universe isnt fixed,its relative.
As humans we have a habit of thinking everything is the way we see it which is a bad thing to think. Just like we assume time is external and not in our minds because it seems that way. Also the way see colours, but also these colours are not external they are just our mind creating them. Not only that but what we see isnt physically there at as all we actually see is light photons not the object we think we see but we forget this dont we.
Everything we see isnt what really is but we struggle to accept that dont you think?

Regarding the ship size I see the ship also contracts as well so I guess I was wrong about the ship getting bigger.

Yea that site was nice thanks. The only reason I brought up this topic was that even though all that information is there I have seen talk on space programs like star trek style programs etc and other programs about
"Faster than light" engines when you cant go faster than light and so many people thinking its impossible to go faster than 1 light year in 1 year and I just wondered why so many people didnt seem to realise light speed is infinite.

16. Jan 2, 2005

### ph_low

well to put it simply, you couldn't reach the speed of light because of fuel.
to keep increasing your acceleration would require more and more fuel, which would in turn make your craft heavier. because your craft is now heavier, it needs MORE fuel to compensate for that and travel faster.
as you see we get into a loop, simply proving you can't reach the speed of light

17. Jan 2, 2005

### Gecko

special relativity forbids objects with mass to go at or exceed the speed of light. no rocket ship ever made will go faster or at the speed of light which is why it is pointless to ask such questions. it is a cool idea though. the problem is you are using a theory that shows the an objects speed relative to itself at light is infinite, but the same theory also forbids us to travel at that speed.