distant planets

[shamrock_uk]

Originally posted by Vaskez: You think we know about the structure of an atom from "looking"? etc.

Almost [img]smile.gif[/img]




Here is a more detailed set of pictures from the famous 'powers of 10' slideshow. This goes much closer than the original slideshow though - you can see individual protons.


Light is the fastest thing in the universe due to this equation:



which shows that your mass would have to tend to infinity as you approach the speed of light. As something gets heavier and heavier it gets progressively harder and harder to accelerate it and thus you can never quite reach lightspeed. This is why we need those massive particle accelerators to get something as ickle as an electron to even near-lightspeed.

Of course, if the maths is wrong...


The 'travelling into the future' thing is just another way of looking at the 'time slowing down' thing. As you get closer to lightspeed time gets slower and slower for you. There's the famous example about you returning to Earth and finding your kids are older than you. You age slower, the faster you go, thus when you arrive back at your reference point things have moved on. In that sense you've travelled into the future [img]smile.gif[/img] And yes, travelling into the past is both theoretically impossible (at least according to current physics) and a real headache in any case [img]tongue.gif[/img]

[ 04-13-2005, 06:53 PM: Message edited by: shamrock_uk ]

[Vaskez]

In those equations, what're L and L' and what's the difference between m and m'? Can't think, too tired to think...

[shamrock_uk]

Bah, I knew you were gonna ask awkward questions. I'd say that they correspond to mass/length when the object is at rest and the changed mass/length when it's in motion.

It's just a way of finding out what the new length would be. As v tends towards 1 (which is c) it all starts to cancel out and you end up with a lovely square root of zero to calculate. Basically showing that v can't equal c.

[Vaskez]

Yes I realise the division by zero results if v = c that's why I didn't ask about that I also said in one of my earlier posts about the mass tending to infinity.

How does length come into it though? I'm not so sure about that. The bottom equation RightHS is the reciprocal of the top one so L'/L = m/m'

The m' and m explanation makes sense. So as the right hand side tends to infinity, the ratio of the masses tends to infinity, and for that to happen, the numerator, m', the mass in moving state, must tend to infinity.

Maths is all good, but I like tangible explanations Do you know how those equations were derived? Or is that getting into THE theory?

[shamrock_uk]

Yeah, that's far beyond me. We just had to learn that form of equation. They're remarkably useful though.

The length comes into it because things also get longer I'm afraid as they get closer to the speed of light. As if your mass changing wasn't enough

[Vaskez]

Ok but L'/L = m/m'

From the equations, the moving mass increases as v increases, but the moving length has to decrease to maintain the equality. So don't you mean things get shorter as the speed increases to the speed of light?

[shamrock_uk]

Yes, quite correct. I was being a monkey [img]smile.gif[/img]

[Azred]

Ok. Shamrock_uk was kind enough to post the equations so I don't have to [img]graemlins/petard.gif[/img] .

As your velocity increases toward the speed of light, your relativistic mass increases (making it more difficult to accelerate you further) and length increases--which is actually space itself elongating. Since space is being stretched, the flow of time must decrease because the speed of light (c) is always 3.0 * 10^8 m/s, regardless of the current conditions of the observer.

Gravity doesn't bend light; gravity bends space-time. Light, being energy, always follows a straight line (or the path of least resistance), but if space is curved then so is the beam of light.

Photons have relativistic mass, which is how they can act as particles as well as waves.
Neutrinos have no relativistic mass, but they are quite weird.
Tachyons never move slower than the speed of light. Anything moving faster than the speed of light is mathematically equivalent to moving backward through time....
Anti-particles (like positrons) are mathematically equivalent to regular particles moving backward through time.

The speed of light is a constant in our 4-dimensonal space-time. However, reality is actually 11-dimensional--brush up on your M theory [img]graemlins/petard.gif[/img] --and in some of those dimensions the speed of light is not an absolute speed limit, allowing faster-than-light travel. This also helps explain things like Bell's experiment, in which formerly-coupled electrons can be separated and one passed through a magnetic field to distort its path but its twin--not passing through a field--will also be distored in the opposite direction. Naturally, this happens instantenously, surpassing the speed of light.
Also, travelling through some of these dimensions allows for teleportation--spatial travel with no intervening time. Scientists have indeed teleported photons in a lab--quite interesting.

Did I miss anything? [img]graemlins/petard.gif[/img]

[Iron Greasel]

How do they know reality has 11 dimensions?

[Link]

Originally posted by Iron Greasel: How do they know reality has 11 dimensions?

They counted them, and then, to be sure, they sent out a letter and asked the dimensions to reply. [img]tongue.gif[/img]

Originally posted by Azred: Ok. Shamrock_uk was kind enough to post the equations so I don't have to [img]graemlins/petard.gif[/img] . Anything moving faster than the speed of light is mathematically equivalent to moving backward through time....

Exactly, mathematically is the issue we're talking about here. Maths will tell us what happened, but actually grasping the concept and understanding what is really happening or what would, practically, happen when something surpasses the speed of light is something entirely different, n'est-ce pas?

[ 04-14-2005, 08:44 AM: Message edited by: Link ]