s***e
发帖数: 911 | 1 Ann. Phys. (Leipzig) 7 (1998) 7 - 8, 618 - 624
It recently has been demonstrated that signals conveyed by evanescent modes
can travel faster than light. In this report some special features of signals
are introduced and investigated, for instance the fundamental property that
signals are frequency band limited. Evanescent modes are characterized by
extraordinary properties: Their energy is negative, they are not directly
measurable, and the evanescent region is not causal since the modes travers | f*******d
发帖数: 339 | 2 I don't know the details, but my bet is that there is no new
"fundamental"
principles to be discovered from this experiment. We know
too well about QED,
it is impossible to have any fundamental new principle
discovered there.
Instead, it is likely that we must be more precise in our
definition or interpretation
of "speed": speed of what? Is speed of signal the same as
speed of energy? What
is "speed of energy?". Those who believe that causality or
Lorentz invariance
is violated in these experime | s***e
发帖数: 911 | 3 有可能吧.
不过至少这个实验里面, signal, energy, and phase speed都被声称是一致的超了光速.
你或许可以找原文看看.
【在 f*******d 的大作中提到】
: I don't know the details, but my bet is that there is no new
: "fundamental"
: principles to be discovered from this experiment. We know
: too well about QED,
: it is impossible to have any fundamental new principle
: discovered there.
: Instead, it is likely that we must be more precise in our
: definition or interpretation
: of "speed": speed of what? Is speed of signal the same as
: speed of energy? What
| q**i
发帖数: 174 | 4
I am always a supporter of faster-than-light travel, :).
However, I find this whole discussion of faster-than-light
not very reliastic. Here is my reasoning.
Assume for a moment that sometime in the future human beings would
master the technology to transmit signals at a speed faster than light.
That means that people in the future can at least send a signal back
to us right now. We have no evidence of that happening, right? so it
means the following must be true:
a) no signal can travel faster
【在 s***e 的大作中提到】
: 有可能吧.
: 不过至少这个实验里面, signal, energy, and phase speed都被声称是一致的超了光速.
: 你或许可以找原文看看.
| s***e
发帖数: 911 | 5
以上的推理是基于SPR的. 如果实物超光速真的存在, 你就不能用SPR来作上述
陈述了.
我是不怎么相信实物超光速, 但是极端好奇这次的实验为什么作者会那样兴奋,
想看看其中是否有什么新东西.
【在 q**i 的大作中提到】
:
: I am always a supporter of faster-than-light travel, :).
: However, I find this whole discussion of faster-than-light
: not very reliastic. Here is my reasoning.
: Assume for a moment that sometime in the future human beings would
: master the technology to transmit signals at a speed faster than light.
: That means that people in the future can at least send a signal back
: to us right now. We have no evidence of that happening, right? so it
: means the following must be true:
: a) no signal can travel faster
| m****i
发帖数: 159 | 6 赫赫,你漏了一种可能性,就是也许时间旅行不是
什么时候的过去都是可能回去的.比如,有一种理
论好像说只有人类掌握某种技术后,才能在那时开
一个时间的"站",而时间旅行只可能回到这样的
"站".如果真是这样,那在我们还没有掌握这种技
术之前,是不能指望有未来游客的.
【在 q**i 的大作中提到】
:
: I am always a supporter of faster-than-light travel, :).
: However, I find this whole discussion of faster-than-light
: not very reliastic. Here is my reasoning.
: Assume for a moment that sometime in the future human beings would
: master the technology to transmit signals at a speed faster than light.
: That means that people in the future can at least send a signal back
: to us right now. We have no evidence of that happening, right? so it
: means the following must be true:
: a) no signal can travel faster
| q**i
发帖数: 174 | 7
putting aside any theory and just look at the reality, sending a signal, or
a tangible object, back to the past and even alter the historical
events doesn't seem to be feasible. If they were, we should have observed
them by now.
The fact that we haven't seen anything close to that is a strong argument
against traveling back to the past.
【在 s***e 的大作中提到】
:
: 以上的推理是基于SPR的. 如果实物超光速真的存在, 你就不能用SPR来作上述
: 陈述了.
: 我是不怎么相信实物超光速, 但是极端好奇这次的实验为什么作者会那样兴奋,
: 想看看其中是否有什么新东西.
|
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