61–70 of 88 posts
re: point 18: It is quite possible to get around this paradox, if you have absolute time. Absolute time means you can't send a message back in absolute time, which means you can't get 'causal loops'.
Which, according to our best current theories, we don't.
Earlier quoted context omitted.
lfuller is right. For example, if you have a ship capable of continuous acceleration at 1g, you can reach any point in the universe on the order of ~50 years.
Can you continuously accelerate at g for 50 years without going over the speed of light? According to wolfram alpha http://www.wolframalpha.com/input/?i=speed+of+light%2Flittle... it would take a year to get to the speed of light at 1g (if my equation was right.) Then you can't speed up anymore.
Generally when we talk about an object's acceleration, we are talking about its acceleration in its own reference frame. By definition, an object's velocity in its own reference frame is always 0, so acceleration does not become more difficult (ignoring the fact that the surrounding matter will be impacting you at higher speeds). From the perspective of an outside observer who is not accelerating, time would appear to slow down on the accelerating object, and the outside observer would record a decreasing acceleration.
The consensus interpretation is that FTL is not possible in normal space, since the speed of something is just another way of looking at how "fast" it travels through time - FTL becomes impossible by definition. However, there is reason to assume a lot of things may be going on that are not strictly speaking taking place in normal flat space. The article mentions the expansion of the universe as an example, and that'…
> The consensus interpretation is that FTL is not possible in normal space I don't think this really makes sense, because "normal space" is not a well-defined term. What our current relativistic theories say is that spacetime contains a causal structure marked out by light cones, and nothing can move outside the light cones. In certain spacetimes (like the one that describes our expanding universe), it is possible to…
You are of course technically correct.
> There's nothing in the actual math that corresponds to "new space being created".
True, and this might end up being a horrible crutch, but right now it helps me to conceptualize what's (possibly) going on. I'm sorry for having exported this hypothesis into a context where it shouldn't have been said without additional qualifiers, but it's too late now to edit it out.
> This isn't really part of the physics either; it's an interpretation
That's actually one I stand by. In the end, this seems really more about how you choose to express ideas in a language that doesn't have any exact words for things going on in an object that lies far outside of our normal experience. You might (and I suspect you do) choose to not say anything at all and let equations speak for themselves, but that doesn't really work for most people. So you're stuck with choosing lenses that render this foreign reality on a canvas you can actually picture. I also think there is nothing wrong in principle about choosing this particular representation.
> I would say it's most likely not possible on our best current theories.
Well, we know spacetime is not rigid. We know that interesting dynamics exist at the extreme limits of physical values. We also know that there is a large chunk yet to be discovered about the nature of the substrate on which reality rests. You are completely within your rights to look at everything we know and have ruled out so far and proclaim a high likelihood of impossibility, but along the same line of thought I reserve the right to declare the glass half full ;)
The truth is that neither of us are likely to live to see a definite answer play out.
Earlier quoted context omitted.
Can you continuously accelerate at g for 50 years without going over the speed of light? According to wolfram alpha http://www.wolframalpha.com/input/?i=speed+of+light%2Flittle... it would take a year to get to the speed of light at 1g (if my equation was right.) Then you can't speed up anymore.
Your equation is correct in a Newtonian universe, but does not consider relativistic effects. Generally when we talk about an object's acceleration, we are talking about its acceleration in its own reference frame. By definition, an object's velocity in its own reference frame is always 0, so acceleration does not become more difficult (ignoring the fact that the surrounding matter will be impacting you at higher spe…
Earlier quoted context omitted.
> The consensus interpretation is that FTL is not possible in normal space I don't think this really makes sense, because "normal space" is not a well-defined term. What our current relativistic theories say is that spacetime contains a causal structure marked out by light cones, and nothing can move outside the light cones. In certain spacetimes (like the one that describes our expanding universe), it is possible to…
> I don't think this really makes sense, because "normal space" is not a well-defined term. You are of course technically correct. > There's nothing in the actual math that corresponds to "new space being created". True, and this might end up being a horrible crutch, but right now it helps me to conceptualize what's (possibly) going on. I'm sorry for having exported this hypothesis into a context where it shouldn't h…
If you mean, you like using it as an interpretation, no problem; a lot of people do.
If you mean you think it's more than an interpretation, then you're going to have to show me explicitly where in the math the "flow of space" is represented.
Earlier quoted context omitted.
lfuller is right. For example, if you have a ship capable of continuous acceleration at 1g, you can reach any point in the universe on the order of ~50 years.
Can you continuously accelerate at g for 50 years without going over the speed of light? According to wolfram alpha http://www.wolframalpha.com/input/?i=speed+of+light%2Flittle... it would take a year to get to the speed of light at 1g (if my equation was right.) Then you can't speed up anymore.
After two years: 89.9%
After four years: 97.2%
After eight years: 99.3%
Earlier quoted context omitted.
> I don't think this really makes sense, because "normal space" is not a well-defined term. You are of course technically correct. > There's nothing in the actual math that corresponds to "new space being created". True, and this might end up being a horrible crutch, but right now it helps me to conceptualize what's (possibly) going on. I'm sorry for having exported this hypothesis into a context where it shouldn't h…
> That's actually one I stand by. If you mean, you like using it as an interpretation, no problem; a lot of people do. If you mean you think it's more than an interpretation, then you're going to have to show me explicitly where in the math the "flow of space" is represented.
I'm having some trouble picturing how it could be more than an interpretation.
The consensus interpretation is that FTL is not possible in normal space, since the speed of something is just another way of looking at how "fast" it travels through time - FTL becomes impossible by definition. However, there is reason to assume a lot of things may be going on that are not strictly speaking taking place in normal flat space. The article mentions the expansion of the universe as an example, and that'…
Interesting. Especially if the AI can learn and evolve along the way.
> But multiverses are entirely out of keeping with the Ockham's Razor approach to doing science, and constitute more of a popular interpretation of quantum mechanics than a serious physical theory. The multiverse is not a theory - it's a logical consequence of a simple theory. This claim is logically akin to claiming that the universe is identical to the observable universe, because to propose that matter exists outs…
For example, in an expanding universe we expect lots of galaxies that we see now to end up beyond the observable horizon in the future. Should we assume they stop existing when they cross that horizon (minimizing # of things) or should we avoid adding an extra rule that removes things that cross out of our horizon?
Many worlds is just quantum physics without collapse. It replaces a rule with a whole lot of things. It is both simpler and more complex than Copenhagen, depending on how you weigh simplicity.
Earlier quoted context omitted.
> That's actually one I stand by. If you mean, you like using it as an interpretation, no problem; a lot of people do. If you mean you think it's more than an interpretation, then you're going to have to show me explicitly where in the math the "flow of space" is represented.
Yes, I'm using it as a mental representation of a process which I can't picture directly. How do you deal with such things? I mean aren't you ever tempted to use a tool like that? I don't think there is anything wrong with the idea. I'm having some trouble picturing how it could be more than an interpretation.