spacetime and mass/energy

[PeriapsisPrograde]

Becuase I was bored beyond reasonable levels today, I have a few questions. Maybe this will spur a good discussion.

1. Are spacetime and mass independent? One can exist without the other?
2. How about spacetime and energy?
3. Since mass and energy are equivalent, (E=mc^2) are they fundamentally the same thing?
4. Could mass or energy exist before space and time?

 

[Keatah]

Becuase I was bored beyond reasonable levels today, I have a few questions. Maybe this will spur a good discussion.

1. Are spacetime and mass independent? One can exist without the other?
2. How about spacetime and energy?
3. Since mass and energy are equivalent, (E=mc^2) are they fundamentally the same thing?
4. Could mass or energy exist before space and time?

1. IMHO, yes they are independent.
2. Also independent.
3. Definitely absolutely yes.
4. Yes. Both.

Now, the more fundamental question, from which those 4 questions can be answered if we answer, "How small is the smallest thing, and how big is the biggest thing?"

Surprisingly simple questions with no easy answer. When does the universe stop "going on" and what lies beyond that. Remarkable isn't it?

 

[Cras]

Mass and spacetime may be indepdenent, but mass only expresses itself through spacetime, am I right? The current ideas on mass is that it is not an interaction with spacetime that determines mass, but the mass does directly determine how much that partical warps the fabric of space.

However, be it string vibrations or the Higgs field, these things have to happen in a dimension, especially in string theory, so I would have to say as they are independent, no understanding of it as we currently have shows it can exist without a spacial dimension. Even in the old point particle model, you still have a field right? so I would say mass cannot exist without spacetime, but I would take that further, that without space, there is no matter.

Quantum mechanics shows that energy and matter can spontaneously appear and disappear in the tinest of distances, so to say they are independent is a bit hasty.

E=MC^2 shows that they are related, but not neccesarily the same thing. However string theory would suggest that matter is closely related to energy, but related is not the same as saying they are the same thing.

Energy it appears did exist before space/time, as something kicked off the Big Bang, but of course again things get more interesting with string theory as the concept of distance as we know it go out the window in certain circumstances, one of them being the condition of the universe at the Big Bang.

Staying in the world of strings, we can at least answer one of those fundamental questions, and we know how small is the smallest thing, but if String Theory is totally wrong then we are back to square one.

 

[2Gm over cxc]

Becuase I was bored beyond reasonable levels today, I have a few questions. Maybe this will spur a good discussion.

1. Are spacetime and mass independent? One can exist without the other?
2. How about spacetime and energy?
3. Since mass and energy are equivalent, (E=mc^2) are they fundamentally the same thing?
4. Could mass or energy exist before space and time?

1. No. Look at it this way, mass is a quality that effects space-time. Without space-time, what is mass? To me, it would be a meaningless set of quantities, if any at all! It's like asking what Mach your going in space...you can use a simple conversion of m/s, however this assumes there is atmospheric pressure, which there isn't. To have a speed of sound, one must be in a medium which can support sound. I believe this is why singularities are so mysterious. Describing how a black hole's mass effects the surrounding space-time it is clear. However, how do you describe the mass's effect in a single point, or a breakdown of space-time? I haven't seriously followed astrophysics in a couple of years though, I'm not sure what has been learned since then.

In regards to string-theory, to me it is still too theoretical and mathematical to know what its real-life implications are. When dealing purely with mathematics, as opposed to empirical observations, one must be careful not to use fifty pages of equations to show that T=T.

2. Same thing.
3. Interesting question. More in the field of philosophy if you ask me. Are all brands of vanilla ice cream the same? How about ice cream? Food? Nutrition? It all depends on how one defines the "same." This could be subjective taste, calorie count, flavor, chemical makeup. How fundamental do you want to go? I think if you go far enough, your answer will be yes, but at that level, I think things will be so similar to each other that there would be no point defining anything. Here's an orbiter analogy: Lets say your preparing for an ejection burn from earth to Neptune. Is 0.00001 dV fundamentally different from 0.000009? Yes, when you look at the macro effects, no when you examine your position after 1 second.