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[mainiac]

Sorry if I sound kinda mean, it's the sleep exhaustion speaking.  But isn't that kinda stupid?  You make a lot of bad assumptions.  Whatever theories you come up with aren't going to be science, they're going to be mental games you play with yourself.  I do the same thing myself, but with more abstract ideas.  I prefer to learn from those who came before with as unforgiving a study as science.  Even Einstein faded into irrelevance when he started thinking he could just figure everything out on his own.

[Ampersand]

Aristotle viewed science in exactly the same way.

He was also wrong.

[mainiac]

Same way as which of us?

[Ampersand]

Sean.

[Sean Mirrsen]

Hehe, wow, got compared to Aristotle. I'm not saying that I disregard everything others learned, I just don't take existing knowledge for a fact. Which allows me to practice wild guesses and "bad assumptions" on matters other people wouldn't touch with a ten foot pole because they're "already established". Like the nature of light and transfer of energy. And I'm not saying I firmly believe in everything I state either. I described the scientific progress of my Multiworlds universe in some other thread - that's exactly what I'm going by. No law is complete and unchallengeable, especially if logic would have you believe that things work differently.

[Yanlin]

The nature of light and transfer of energy are NOT firmly established.

They are heavily theorized.

[Sergius]

Why exactly does acceleration become difficult?

You know, I've been thinking about it, and it shames me to admit, that I'm at loss as to why it is supposed to be so. After all, the thing that first comes to mind is the relativistic mass increase, that would need more and more force to accelerate it by the same factor. Yet, the mass increase is associated with the frame of reference that is moving, i.e. from the point of view of the ship, it's the planets that are moving. So it's the planets that should gain mass, not the spaceship, no? Somebody help me here.

I'm not so sure about this, but I believe that's a consequence of dilation and not actually lack of acceleration. From your POV, you keep accelerating at the same rate, so you ARE going "faster and faster", but from the external POV you seem to be accelerating less and less. Or is it the other way around? That's why as you approach C, the people inside the ship could perceive a trip to be (near) instant, while people outside will still think you still took 4 or more years to reach the nearest star.

Also, not doing any actual math here, so only the idea counts, not the actual numbers and proportions: let's say you accelerate from 0.90 C to 0.91 C. From an outside POV you just shaved maybe a few days from your (4 year) trip, but inside, it may appears to you that you doubled your speed (because the energy required to do such thing "should" have accelerated you to twice your speed) so what you woul dhave perceived as a (pulling out of my ass number) 3 months, took only month and a half.

[Virex]

The nature of light and transfer of energy are NOT firmly established.

They are heavily theorized.

You can theorise about the nature of light all you want, but for the discussion at hand it's sufficient to say that there have been extensive measurements of the impulse conveyed by light to a particle (http://www.lpi.usra.edu/meetings/dust2005/pdf/4010.pdf) and to mirrors: (http://rspa.royalsocietypublishing.org/content/360/1702/347.full.pdf+html). Another study showed that it's possible to cancel out the thermal motion of a mirror by using a laser to generate radiation pressure: http://www.articlearchives.com/science-technology/physics-lasers/1652418-1.html, though I was not able to retrieve the original document of this study.

Now it's of course up to debate whether this means that light actually has mass. However, there's another kind of circumstantial evidence that points in that direction, namely that light is influenced by gravity. The most spectacular example of this is seen in the following paper: http://hubblesite.org/pubinfo/pdf/2008/04/pdf.pdf. This paper describes the discovery of a so called double einstein ring, in which light is bend twice to generate a very specific shape, which is described in this related article as a bulls-eye patern.

[Granite26]

I don't think that the argument of "If something isn't already very old, chances are it won't last a long time anyway" is very valid.

Sorta true but not really...

There's math behind it, but poorly used.


Just to throw another wrench in the machine:  Is there any real reason to believe that light is traveling at the speed of light?  All we know is that light propagates at a certain rate relative to us, and everything kinda bends around so that the fastest rate anything can move is c.  It's already established that if you start chasing light, it's source will be redshifted.  That is, pushing light harder increases the energy, but does not APPEAR to make it faster

[Servant Corps]

* Servant Corps facepalms.

[Granite26]

What I'm saying is that when things are moving at relativistic speeds, they get bonked up.  Just because you can't MEASURE something moving at faster than the speed of light doesn't mean that putting out enough thrust to do so just magically doesn't work.  The power goes in other directions (time/space dilation) which has suspiciously similar net effects to accelerating more.

In other words:  Photons are 'travelling' at the speed of light relative to us.  What does the universe look like from the PoV of the Photon?  What happens if you calculate the red shift on an object going .99c away from you?  Current theory says you'll still measure that photon as going c, but it'll be redshift out of existance, doesn't it?

[mainiac]

Hehe, wow, got compared to Aristotle. I'm not saying that I disregard everything others learned, I just don't take existing knowledge for a fact. Which allows me to practice wild guesses and "bad assumptions" on matters other people wouldn't touch with a ten foot pole because they're "already established". Like the nature of light and transfer of energy. And I'm not saying I firmly believe in everything I state either. I described the scientific progress of my Multiworlds universe in some other thread - that's exactly what I'm going by. No law is complete and unchallengeable, especially if logic would have you believe that things work differently.

If you are going to eschew the practice of making good assumptions, then you really have no role in calling you essentially unfounded conclusions "realistic."  And it's kinda annoying if you tell other people they are wrong because they don't use your assumptions.  Especially if some of those assumptions are patently false.

[Virex]

Just to throw another wrench in the machine:  Is there any real reason to believe that light is traveling at the speed of light?  All we know is that light propagates at a certain rate relative to us, and everything kinda bends around so that the fastest rate anything can move is c.  It's already established that if you start chasing light, it's source will be redshifted.  That is, pushing light harder increases the energy, but does not APPEAR to make it faster

Exactly what do you mean? Experimental evidence that the speed of light is the same for all observers?

[Granite26]

Just to throw another wrench in the machine:  Is there any real reason to believe that light is traveling at the speed of light?  All we know is that light propagates at a certain rate relative to us, and everything kinda bends around so that the fastest rate anything can move is c.  It's already established that if you start chasing light, it's source will be redshifted.  That is, pushing light harder increases the energy, but does not APPEAR to make it faster

Exactly what do you mean? Experimental evidence that the speed of light is the same for all observers?

Right, but the energy of the particle is observed as being different (redshift).
Isn't the energy of a(non relativistic) object Speed * Mass?  Is the mass different for different observers, or is it the speed?  I know that I am incorrectly conflating relativistic physics from non, but still, isn't it a little bit creepy?

[mainiac]

The kinetic energy is (.5)*(velocity squared)*(mass).

The mass is only different due to relativity.  So at speeds that aren't a substantial fraction of the speed of light, the mass doesn't change a perceptible amount.  The velocity is relative to the observer in Newtonian mechanics.  From the perspective of somebody in the same room as you, you can be stationary.  But from the perspective of someone on the moon, you are moving quite quickly.