分类存档: 物理

物理是我的初恋. 此类别包含职位最接近我的心脏. 今后二十年, 如果这个博客生存, 这一类很可能会牵着我的最持久的见解. 从现在开始200年, 如果我记得在所有, 这将是这些见解; 不是因为我是什么样的人, 这笔钱我做, 也没有别的. Only for my first and last love…

知觉, 物理与光在哲学中的作用

现实, 因为我们感觉到它, 是不是很真实. 星星,我们在夜空中看到, 例如, 是不是真的有. 他们可能已移动,甚至通过我们能看到他们的死亡时间. 这不现实是因为它需要的光从遥远的恒星和星系的时间到达我们. 我们知道这种延迟.

即使我们知道这么好,太阳已经被我们看到它的时候8分钟老. 这一事实似乎并没有出现特别严重的认识论问题 – 如果我们想知道现在是怎么回事太阳, 所有我们需要做的就是等待八分钟. 我们只需要“正确的’ 对于因光线的有限速度的扭曲,我们的看法,我们才可以相信我们所看到的. 在看到了同样的现象在我们感知移动物体的方式鲜为人知的体现. 有些天体看起来就好像他们正在数次光速, 而他们的实际’ 速度必须比少很多.

令人惊讶 (而很少强调) 是当涉及到​​敏感的议案, 我们不能反算中相同种类的方法,我们可以以校正的延迟在观测的太阳. 如果我们看到一个天体运动以罢课高速, 我们无法计算它的速度有多快,甚至在什么方向是'真’ 动,而不必首先做出一定的假设进一步.

爱因斯坦之所以选择在物理学领域的治疗观念的扭曲,创造新的基本性质来解决问题 – 在空间和时间的说明. 狭义相对性理论的一个核心思想是需要时间的活动的有序序列的人类观念被抛弃. 事实上, 因为它需要时间的光从一个事件,在一个遥远的地方找到我们, 并为我们成为意识到这一点, 现'的概念’ 不再让任何意义, 例如, 当我们讲太阳黑子出现在太阳表面上只是此刻的天文学家试图拍摄它的. 同时性是相对的.

爱因斯坦,而不是重新定义同时发生利用瞬间的时候,我们发现事件. 检测, 他将其定义, 涉及光的往返旅费类似雷达探测. 我们发出的光的速度行进的信号, 和等待的反射. 如果从两个事件的反射脉冲到达我们在同一瞬间, 那么他们是同时进行的. 但是看它的另一种方式是简单地调用两个事件“同时发生’ 如果从它们的光在同一时刻到达我们. 换句话说, 我们可以使用由下观测的对象所产生的光,而不是将信号发送给他们,并期待在反射.

这种差异可能听起来像一个吹毛求疵的技术性, 但它确实使一个巨大的差异,我们可以做出预测. 爱因斯坦的选择,导致有许多理想特性的数学图片, 包括制定进一步的理论发展更优雅. 但随后, 爱因斯坦认为, 作为信仰的问题又好像, ,管辖宇宙的规则必须是'优雅。’ 然而, 另一种方法有一个优点,当谈到描述运动中的物体. 由于, 当然, 我们不使用雷达看到运动中的明星; 我们仅仅感测的光 (或其他辐射) 他们来了. 然而,使用这种感官范式, 而不是“类似雷达探测,’ 来形容一个丑陋的数学图片宇宙结果. 爱因斯坦不会批准!

在数学上的差异派生不同的哲学立场, 这反过来渗透到现实我们的物理图像的理解. 作为例证的, 假设我们观察, 通过射电望远镜, 在天空中的两个对象, 以大致相同的形状, 大小和性质. 我们肯定知道的唯一的事情是,从天空中这两个不同点的无线电波到达我们在同一时刻. 我们只能猜测,当海浪开始了他们的旅程.

如果我们假设 (因为我们经常做的) 该波开始的旅程大致在同一时刻, 我们结束了两个“真实的图片’ 对称的叶片或多或少的方式看到它们. 但还有另一种, 不同的可能性,那就是该波起源于同一对象 (这是在运动) 在两个时间不同的时刻, 在同一时刻到达望远镜. 这可能会额外解释这种对称的射电源的一些光谱和时间特性. 因此,这两个图片,我们应该采取以假乱真? 两个对称的物体,因为我们看到他们或一个物体以这样的方式移动,就好像给我们的印象? 是否真的重要哪一个是“真实的”? 是'真正的’ 意味着在这方面的任何?

狭义相对论给出一个明确的答案. 数学排除了移动以这样的方式单一对象的可能性,以模拟的两个对象. 从本质, 我们看到的是什么就在那里. 然而,, 如果我们用我们所认为定义事件, 唯一的哲学立场是有道理的是一个断开的原因说谎背后的现实感测到的是什么感应.

这种脱节的情况并不少见思想的哲学流派. 现象学, 例如, 认为,空间和时间是不客观的现实. 他们只是我们的感知中. 所有这一切发生在时间和空间的现象仅仅是捆绑了我们的看法. 换句话说, 空间和时间是从知觉所产生的认知结构. 因此,, 所有我们所归诸于空间和时间的物理特性只适用于以惊人的现实 (的“东西合在世界的现实’ 因为我们感觉到它. 底层的现实 (持有我们的感知的物理原因), 相比之下, 仍超出了我们的认知范围.

然而,有哲学和现代物理学的观点之间的鸿沟. 不是没有做过诺贝尔奖的物理学家, 史蒂芬温伯格, 不知道, 在他的书终极理论之梦, 为什么从哲学到物理学的贡献是如此令人惊讶的小. 也许是因为物理学尚未达成协议的事实,当谈到看到宇宙, 有没有这样的事,作为一个错觉 – 这大概就是歌德的意思时,他说:, “光学错觉光学真理。’

的区别 (或缺乏) 光学幻觉和真实之间,在哲学最古老的话题之一. 毕竟, 它是关于知识与现实之间的区别. 知识被认为是我们认为对的东西,, 在现实中, 是“真正的情况。’ 换句话说, 知识是一种体现, 或外部的东西精神的形象, 如下面的图中.

ExternalToBrain

在这张照片, 黑色箭头表示创造知识的过程, 其中包括感知, 认知活动, 并实行纯粹理性. 这是图片物理学已经接受. 虽然承认了我们的看法可能是不完美的, 物理学假设,我们可以打通越来越精细的实验密切的外部现实, 和, 更重要的是, 通过更好的理论化. 相对论的特殊和一般的理论是这一观点的现实的辉煌应用例子,简单的物理原理是使用纯粹理性强大的机器的逻辑必然的结论,不懈地追求.

但还有另一种, 知识与现实的另一种观点认为已经存在了很长一段时间. 这是关于感知的现实,我们的感官输入的内部认知表示看法, 如下图所示.

AbsolutelToBrain

在此视图中, 知识和感知的现实是内部认知结构, 虽然我们都来把它们作为单独的. 什么是外部并不现实,因为我们认为它, 但一个不可知的实体后面感觉输入的物理原因引起. 在图示的例子, 第一个箭头表示的感测的过程, 和第二箭头表示认知和逻辑推理步骤. 为了应用这一观点的现实和知识, 大家纷纷猜测绝对现实的本质, 不可知的,因为它是. 一个可能的候选人绝对现实是牛顿力学, 这给出了一个合理的预测为我们感知的现实.

总结, 当我们试图处理由于认知的扭曲, 我们有两个选择, 两个可能的哲学立场. 一种是接受的失真作为我们的空间和时间的一部分, 为狭义相对论不. 另一种选择是,假设有一个“高’ 实际上从我们检测到的现实截然不同, 其属性,我们只能猜想. 换句话说, 一种选择是住在一起的失真, 而另一种是提出​​的猜测为更高的现实. 既不是这些选择是特别有吸引力的. 但猜测路径是相似的接受现象论的观点. 这也导致自然如何现实认知神经科学观察, 它研究的认知背后的生物学机制.

扭曲光线和现实的故事是,我们似乎已经知道这一切很长一段时间. 光在创造我们的现实,还是宇宙中的角色是西方宗教思想的心脏. 宇宙缺乏光线的不只是您已经关掉了灯的世界. 这的确是一个宇宙缺乏自身, 一个不存在的宇宙. 正是在这种背景下,我们必须明白的声明说'地球是没有形式背后的智慧, 和无效的’ 直到神使光线是, 说“要有光。’

可兰经也说, “真主是天地之光,’ 这是反映在古印度的著作之一: 从黑暗走向光明“带领我, 从虚幻到真实带领我。’ 光从虚幻的虚空把我们的角色 (虚无) 以现实确实理解了很长, 很久. 难道古代的圣人和先知知道的事情,我们现在才开始发现我们所有的知识应该进步?

有康德的本体 - 惊人的区别与现象学之后相似之处, 与婆罗门玛雅区别不二. 智慧的现实,从精神的剧目自然是重塑现代神经科学, 它把现实,由大脑产生一种认知表征. 大脑使用感觉输入, 内存, 意识, 甚至语言成分在炮制我们的​​现实感. 这种观点的现实, 然而,, 什么是物理还是未能达成协议了. 但是在某种程度上,它的舞台 (空间和时间) 是现实的一部分, 物理学是不能幸免的哲学.

事实上, 因为我们的知识的界限推向越走越, 我们发现人类努力的不同分支之间迄今没有料​​到,常常令人惊讶的互连. 然而,, 怎么能对我们知识的不同领域是相互独立的,如果所有的知识是主观的? 如果知识仅仅是我们的经验认知表征? 但随后, 它是现代的谬论认为,知识是一个外部的现实我们的内部表示, 因此,与此不同的. 相反,, 认识和利用人类努力的不同域之间的互连可能是在开发我们的集体智慧下一阶段的必不可少的先决条件.

箱: 爱因斯坦的火车一个爱因斯坦的著名思想实验说明了需要重新思考我们所说的同时发生的事件意味着. 它描述了一个高速列车沿直线轨道冲过去的一个小站作为一个男人站在站台上看着它加速通过. 让他吃惊的, 当火车经过他, 2减轻螺栓撞击旁边的列车的任一端的磁迹! (交通方便, 在后来的调查, 他们留下焦痕无论在火车上和地面上。)

该男子, 看来,这两个增亮螺栓撞击在完全相同的时刻. 后来, 由火车轨道地面的痕迹表明,当闪电击中的点都是一模一样等距离他. 此后的闪电螺栓前往朝他相同的距离, 而且由于他们似乎男方发生在完全相同的时刻, 他没有理由不认为闪电击中螺栓在完全相同的时刻. 他们同时.

然而, 后来想了一点, 男人遇到谁碰巧一位女士乘客可坐在餐车, 恰好在列车的中心, 而望着窗外当时闪电击中螺栓. 该乘客告诉他,她首先看到的闪电击中,发动机附近的地面上火车的前部稍稍领先时,第二个打旁边的行李车在列车后部的地面.

效果无关的光不得不前往距离, 同时作为女人和男人都是等距离的两点之间的闪电击中. 然而,他们观察到的事件的顺序完全不同.

事件的定时的这种分歧是不可避免, 爱因斯坦说:, 因为女人实际上是走向地步闪电的闪光的发动机附近打 - 和远离地步闪电击中旁边的行李车闪光. 在时间的少量花费的光线到达女士, 因为火车移动, 第一次闪光必须到她缩的距离, 第二闪光灯需要行驶的距离增长.

这一事实可能不是在火车和飞机的情况下,应注意的, 但是,当涉及到宇宙学距离, 同时性真的没有任何意义. 例如, 两个遥远的超新星爆炸, 被视为从我们地球上的高度,同时, 会出现发生在其他的角度不同时间的组合.

在相对论: 特别及一般理论 (1920), 爱因斯坦这样说吧:

“每一个参考物体 (坐标系统) 有它自己的特定时间; 除非我们被告知的参考团体对时间的语句引用, 还有就是在一个事件的时候声明没有任何意义。’

Tsunami

The Asian Tsunami two and a half years ago unleashed tremendous amount energy on the coastal regions around the Indian ocean. What do you think would’ve have happened to this energy if there had been no water to carry it away from the earthquake? I mean, if the earthquake (of the same kind and magnitude) had taken place on land instead of the sea-bed as it did, presumably this energy would’ve been present. How would it have manifested? As a more violent earthquake? Or a longer one?

I picture the earthquake (in cross-section) as a cantilever spring being held down and then released. The spring then transfers the energy to the tsunami in the form of potential energy, as an increase in the water level. As the tsunami radiates out, it is only the potential energy that is transferred; the water doesn’t move laterally, only vertically. As it hits the coast, the potential energy is transferred into the kinetic energy of the waves hitting the coast (water moving laterally then).

Given the magnitude of the energy transferred from the epicenter, I am speculating what would’ve happened if there was no mechanism for the transfer. Any thoughts?

Universe – Size and Age

I posted this question that was bothering me when I read that they found a galaxy at about 13 billion light years away. My understanding of that statement is: At distance of 13 billion light years, there was a galaxy 13 billion years ago, so that we can see the light from it now. Wouldn’t that mean that the universe is at least 26 billion years old? It must have taken the galaxy about 13 billion years to reach where it appears to be, and the light from it must take another 13 billion years to reach us.

In answering my question, Martin and Swansont (who I assume are academic phycisists) point out my misconceptions and essentially ask me to learn more. All shall be answered when I’m assimilated, it would appear! 🙂

This debate is published as a prelude to my post on the Big Bang theory, coming up in a day or two.

Mowgli 03-26-2007 10:14 PM

Universe – Size and Age
I was reading a post in http://www.space.com/ stating that they found a galaxy at about 13 billion light years away. I am trying to figure out what that statement means. To me, it means that 13 billion years ago, this galaxy was where we see it now. Isn’t that what 13b LY away means? If so, wouldn’t that mean that the universe has to be at least 26 billion years old? I mean, the whole universe started from one singular point; how could this galaxy be where it was 13 billion years ago unless it had at least 13 billion years to get there? (Ignoring the inflationary phase for the moment…) I have heard people explain that the space itself is expanding. What the heck does that mean? Isn’t it just a fancier way of saying that the speed of light was smaller some time ago?
swansont 03-27-2007 09:10 AM

Quote:

Originally Posted by Mowgli
(Post 329204)
I mean, the whole universe started from one singular point; how could this galaxy be where it was 13 billion years ago unless it had at least 13 billion years to get there? (Ignoring the inflationary phase for the moment…)

Ignoring all the rest, how would this mean the universe is 26 billion years old?

Quote:

Originally Posted by Mowgli
(Post 329204)
I have heard people explain that the space itself is expanding. What the heck does that mean? Isn’t it just a fancier way of saying that the speed of light was smaller some time ago?

The speed of light is an inherent part of atomic structure, in the fine structure constant (alpha). If c was changing, then the patterns of atomic spectra would have to change. There hasn’t been any confirmed data that shows that alpha has changed (there has been the occasional paper claiming it, but you need someone to repeat the measurements), and the rest is all consistent with no change.

Martin 03-27-2007 11:25 AM

To confirm or reinforce what swansont said, there are speculation and some fringe or nonstandard cosmologies that involve c changing over time (or alpha changing over time), but the changing constants thing just gets more and more ruled out.I’ve been watching for over 5 years and the more people look and study evidence the LESS likely it seems that there is any change. They rule it out more and more accurately with their data.So it is probably best to ignore the “varying speed of light” cosmologies until one is thoroughly familiar with standard mainstream cosmology.You have misconceptions Mowgli

  • General Relativity (the 1915 theory) trumps Special Rel (1905)
  • They don’t actually contradict if you understand them correctly, because SR has only a very limited local applicability, like to the spaceship passing by:-)
  • Wherever GR and SR SEEM to contradict, believe GR. It is the more comprehensive theory.
  • GR does not have a speed limit on the rate that very great distances can increase. the only speed limit is on LOCAL stuff (you can’t catch up with and pass a photon)
  • So we can and DO observe stuff that is receding from us faster than c. (It’s far away, SR does not apply.)
  • This was explained in a Sci Am article I think last year
  • Google the author’s name Charles Lineweaver and Tamara Davis.
  • We know about plenty of stuff that is presently more than 14 billion LY away.
  • You need to learn some cosmology so you wont be confused by these things.
  • Also a “singularity” does not mean a single point. that is a popular mistake because the words SOUND the same.
  • A singularity can occur over an entire region, even an infinite region.

Also the “big bang” model doesn’t look like an explosion of matter whizzing away from some point. It shouldn’t be imagined like that. The best article explaining common mistakes people have is this Lineweaver and Davis thing in Sci Am. I think it was Jan or Feb 2005 but I could be a year off. Google it. Get it from your local library or find it online. Best advice I can give.

Mowgli 03-28-2007 01:30 AM

To swansont on why I thought 13 b LY implied an age of 26 b years:When you say that there is a galaxy at 13 b LY away, I understand it to mean that 13 billion years ago my time, the galaxy was at the point where I see it now (which is 13 b LY away from me). Knowing that everything started from the same point, it must have taken the galaxy at least 13 b years to get where it was 13 b years ago. So 13+13. I’m sure I must be wrong.To Martin: You are right, I need to learn quite a bit more about cosmology. But a couple of things you mentioned surprise me — how do we observe stuff that is receding from as FTL? I mean, wouldn’t the relativistic Doppler shift formula give imaginary 1+z? And the stuff beyond 14 b LY away – are they “outside” the universe?I will certainly look up and read the authors you mentioned. Thanks.
swansont 03-28-2007 03:13 AM

Quote:

Originally Posted by Mowgli
(Post 329393)
To swansont on why I thought 13 b LY implied an age of 26 b years:When you say that there is a galaxy at 13 b LY away, I understand it to mean that 13 billion years ago my time, the galaxy was at the point where I see it now (which is 13 b LY away from me). Knowing that everything started from the same point, it must have taken the galaxy at least 13 b years to get where it was 13 b years ago. So 13+13. I’m sure I must be wrong.

That would depend on how you do your calibration. Looking only at a Doppler shift and ignoring all the other factors, if you know that speed correlates with distance, you get a certain redshift and you would probably calibrate that to mean 13b LY if that was the actual distance. That light would be 13b years old.

But as Martin has pointed out, space is expanding; the cosmological redshift is different from the Doppler shift. Because the intervening space has expanded, AFAIK the light that gets to us from a galaxy 13b LY away is not as old, because it was closer when the light was emitted. I would think that all of this is taken into account in the measurements, so that when a distance is given to the galaxy, it’s the actual distance.

Martin 03-28-2007 08:54 AM

Quote:

Originally Posted by Mowgli
(Post 329393)
I will certainly look up and read the authors you mentioned.

This post has 5 or 6 links to that Sci Am article by Lineweaver and Davis

http://scienceforums.net/forum/showt…965#post142965

It is post #65 on the Astronomy links sticky thread

It turns out the article was in the March 2005 issue.

I think it’s comparatively easy to read—well written. So it should help.

When you’ve read the Sci Am article, ask more questions—your questions might be fun to try and answer:-)

Twin Paradox – Take 2

The Twin Paradox is usually explained away by arguing that the traveling twin feels the motion because of his acceleration/deceleration, and therefore ages slower.

But what will happen if the twins both accelerate symmetrically? That is, they start from rest from one space point with synchronized clocks, and get back to the same space point at rest by accelerating away from each other for some time and decelerating on the way back. By the symmetry of the problem, it seems that when the two clocks are together at the end of the journey, at the same point, and at rest with respect to each other, they have to agree.

Then again, during the whole journey, each clock is in motion (accelerated or not) with respect to the other one. In SR, every clock that is in motion with respect to an observer’s clock is supposed run slower. Or, the observer’s clock is always the fastest. So, for each twin, the other clock must be running slower. However, when they come back together at the end of the journey, they have to agree. This can happen only if each twin sees the other’s clock running faster at some point during the journey. What does SR say will happen in this imaginary journey?

(Note that the acceleration of each twin can be made constant. Have the twins cross each other at a high speed at a constant linear deceleration. They will cross again each other at the same speed after sometime. During the crossings, their clocks can be compared.)

Unreal Time

Farsight wrote:Time is a velocity-dependent subjective measure of event succession rather than something fundamental – the events mark the time, the time doesn’t mark the events. This means the stuff out there is space rather than space-time, and is an “aether” veiled by subjective time.

I like your definition of time. It is close to my own view that time is “unreal.” It is possible to treat space as real and space-time as something different, as you do. This calls for some careful thought. I will outline my thinking in this post and illustrate it with an example, if my friends don’t pull me out for lunch before I can finish. :)

The first question we need to ask ourselves is why space and time seem coupled? The answer is actually too simple to spot, and it is in your definition of time. Space and time mix through our concept of velocity and our brain’s ability to sense motion. There is an even deeper connection, which is that space is a cognitive representation of the photons inputs to our eyes, but we will get to it later.

Let’s assume for a second that we had a sixth sense that operated at an infinite speed. That is, if star explodes at a million light years from us, we can sense it immediately. We will see it only after a million years, but we sense it instantly. I know, it is a violation of SR, cannot happen and all that, but stay with me for a second. Now, a little bit of thinking will convince you that the space that we sense using this hypothetical sixth sense is Newtonian. Here, space and time can be completely decoupled, absolute time can be defined etc. Starting from this space, we can actually work out how we will see it using light and our eyes, knowing that the speed of light is what it is. It will turn out, clearly, that we seen events with a delay. That is a first order (or static) effect. The second order effect is the way we perceive objects in motion. It turns out that we will see a time dilation and a length contraction (for objects receding from us.)

Let me illustrate it a little further using echolocation. Assume that you are a blind bat. You sense your space using sonar pings. Can you sense a supersonic object? If it is coming towards you, by the time the reflected ping reaches you, it has gone past you. If it is going away from you, your pings can never catch up. In other words, faster than sound travel is “forbidden.” If you make one more assumption – the speed of the pings is the same for all bats regardless of their state of motion – you derive a special relativity for bats where the speed of sound is the fundamental property of space and time!

We have to dig a little deeper and appreciate that space is no more real than time. Space is a cognitive construct created out of our sensory inputs. If the sense modality (light for us, sound for bats) has a finite speed, that speed will become a fundamental property of the resultant space. And space and time will be coupled through the speed of the sense modality.

This, of course, is only my own humble interpretation of SR. I wanted to post this on a new thread, but I get the feeling that people are a little too attached to their own views in this forum to be able to listen.

Leo wrote:Minkowski spacetime is one interpretation of the Lorentz transforms, but other interpretations, the original Lorentz-Poincaré Relativity or modernized versions of it with a wave model of matter (LaFreniere or Close or many others), work in a perfectly euclidean 3D space.

So we end up with process slowdown and matter contraction, but NO time dilation or space contraction. The transforms are the same though. So why does one interpretation lead to tensor metric while the others don’t? Or do they all? I lack the theoretical background to answer the question.

Hi Leo,

If you define LT as a velocity dependent deformation of an object in motion, then you can make the transformation a function of time. There won’t be any warping and complications of metric tensors and stuff. Actually what I did in my book is something along those lines (though not quite), as you know.

The trouble arises when the transformation matrix is a function of the vector is transforming. So, if you define LT as a matrix operation in a 4-D space-time, you can no longer make it a function of time through acceleration any more than you can make it a function of position (as in a velocity field, for instance.) The space-time warping is a mathematical necessity. Because of it, you lose coordinates, and the tools that we learn in our undergraduate years are no longer powerful enough to handle the problem.

Of Rotation, LT and Acceleration

In the “Philosophical Implications” forum, there was an attempt to incorporate acceleration into Lorentz transformation using some clever calculus or numerical techniques. Such an attempt will not work because of a rather interesting geometric reason. I thought I would post the geometric interpretation of Lorentz transformation (or how to go from SR to GR) here.

Let me start with a couple of disclaimers. First of, what follows is my understanding of LT/SR/GR. I post it here with the honest belief that it is right. Although I have enough academic credentials to convince myself of my infallibility, who knows? People much smarter than me get proven wrong every day. And, if we had our way, we would prove even Einstein himself wrong right here in this forum, wouldn’t we? :D Secondly, what I write may be too elementary for some of the readers, perhaps even insultingly so. I request them to bear with it, considering that some other readers may find it illuminating. Thirdly, this post is not a commentary on the rightness or wrongness of the theories; it is merely a description of what the theories say. Or rather, my version of what they say. With those disclaimers out of the way, let’s get started…

LT is a rotation in the 4-D space-time. Since it not easy to visualize 4-D space-time rotation, let’s start with a 2-D, pure space rotation. One fundamental property of a geometry (such as 2-D Euclidean space) is its metric tensor. The metric tensor defines the inner product between two vectors in the space. In normal (Euclidean or flat) spaces, it also defines the distance between two points (or the length of a vector).

Though the metric tensor has the dreaded “tensor” word in its name, once you define a coordinate system, it is only a matrix. For Euclidean 2-D space with x and y coordinates, it is the identity matrix (two 1’s along the diagonal). Let’s call it G. The inner product between vectors A and B is A.B = Trans(A) G B, which works out to be a_1b_1+a_2b_2. Distance (or length of A) can be defined as \sqrt{A.A}.

So far in the post, the metric tensor looks fairly useless, only because it is the identity matrix for Euclidean space. SR (or LT), on the other hand, uses Minkowski space, which has a metric that can be written with [-1, 1, 1, 1] along the diagonal with all other elements zero – assuming time t is the first component of the coordinate system. Let’s consider a 2-D Minkowski space for simplicity, with time (t) and distance (x) axes. (This is a bit of over-simplification because this space cannot handle circular motion, which is popular in some threads.) In units that make c = 1, you can easily see that the invariant distance using this metric tensor is \sqrt{x^2 - t^2}.

Continued…

The Unreal Universe — Discussion with Gibran

Hi again,You raise a lot of interesting questions. Let me try to answer them one by one.

You’re saying that our observations of an object moving away from us would look identical in either an SR or Galilean context, and therefore this is not a good test for SR.

What I’m saying is slightly different. The coordinate transformation in SR is derived considering only receding objects and sensing it using radar-like round trip light travel time. It is then assumed that the transformation laws thus derived apply to all objects. Because the round trip light travel is used, the transformation works for approaching objects as well, but not for things moving in other directions. But SR assumes that the transformation is a property of space and time and asserts that it applies to all moving (inertial) frames of reference regardless of direction.

We have to go a little deeper and ask ourselves what that statement means, what it means to talk about the properties of space. We cannot think of a space independent of our perception. Physicists are typically not happy with this starting point of mine. They think of space as something that exists independent of our sensing it. And they insist that SR applies to this independently existing space. I beg to differ. I consider space as a cognitive construct based on our perceptual inputs. There is an underlying reality that is the cause of our perception of space. It may be nothing like space, but let’s assume, for the sake of argument, that the underlying reality is like Galilean space-time. How would be perceive it, given that we perceive it using light (one-way travel of light, not two-way as SR assumes)? It turns out that our perceptual space would have time dilation and length contraction and all other effect predicted by SR. So my thesis is that the underlying reality obeys Galilean space-time and our perceptual space obeys something like SR. (It is possible that if I assume that our perception uses two-way light travel, I may get SR-like transformation. I haven’t done it because it seems obvious to me that we perceive a star, for instance, by sensing the light from it rather than flashing a light at it.)

This thesis doesn’t sit well with physicists, and indeed with most people. They mistake “perceptual effects” to be something like optical illusions. My point is more like space itself is an illusion. If you look at the night sky, you know that the stars you see are not “real” in the sense that they are not there when you are looking at them. This is simply because the information carrier, namely light, has a finite speed. If the star under observation is in motion, our perception of its motion is distorted for the same reason. SR is an attempt to formalize our perception of motion. Since motion and speed are concepts that mix space and time, SR has to operate on “space-time continuum.” Since SR is based on perceptual effects, it requires an observer and describes motion as he perceives it.

But are you actually saying that not a single experiment has been done with objects moving in any other direction than farther away? And what about experiments on time dilation where astronauts go into space and return with clocks showing less elapsed time than ones that stayed on the ground? Doesn’t this support the ideas inherent in SR?

Experiments are always interpreted in the light of a theory. It is always a model based interpretation. I know that this is not a convincing argument for you, so let me give you an example. Scientists have observed superluminal motion in certain celestial objects. They measure the angular speed of the celestial object, and they have some estimate of its distance from us, so they can estimate the speed. If we didn’t have SR, there would be nothing remarkable about this observation of superluminality. Since we do have SR, one has to find an “explanation” for this. The explanation is this: when an object approaches us at a shallow angle, it can appear to come in quite a bit faster than its real speed. Thus the “real” speed is subluminal while the “apparent” speed may be superluminal. This interpretation of the observation, in my view, breaks the philosophical grounding of SR that it is a description of the motion as it appears to the observer.

Now, there are other observations of where almost symmetric ejecta are seen on opposing jets in symmetric celestial objects. The angular speeds may indicate superluminality in both the jets if the distance of the object is sufficiently large. Since the jets are assumed to be back-to-back, if one jet is approaching us (thereby giving us the illusion of superluminality), the other jet has bet receding and can never appear superluminal, unless, of course, the underlying motion is superluminal. The interpretation of this observation is that the distance of the object is limited by the “fact” that real motion cannot be superluminal. This is what I mean by experiments being open to theory or model based interpretations.

In the case of moving clocks being slower, it is never a pure SR experiment because you cannot find space without gravity. Besides, one clock has to be accelerated or decelerated and GR applies. Otherwise, the age-old twin paradox would apply.

I know there have been some experiments done to support Einstein’s theories, like the bending of light due to gravity, but are you saying that all of them can be consistently re-interpreted according to your theory? If this is so, it’s dam surprising! I mean, no offense to you – you’re obviously a very bright individual, and you know much more about this stuff than I do, but I’d have to question how something like this slipped right through physicists’ fingers for 100 years.

These are gravity related questions and fall under GR. My “theory” doesn’t try to reinterpret GR or gravity at all. I put theory in inverted quotes because, to me, it is a rather obvious observation that there is a distinction between what we see and the underlying causes of our perception. The algebra involved is fairly simple by physics standards.

Supposing you’re right in that space and time are actually Galilean, and that the effects of SR are artifacts of our perception. How then are the results of the Michelson-Morley experiments explained? I’m sorry if you did explain it in your book, but it must have flown right over my head. Or are we leaving this as a mystery, an anomaly for future theorists to figure out?

I haven’t completely explained MMX, more or less leaving it as a mystery. I think the explanation hinges on how light is reflected off a moving mirror, which I pointed out in the book. Suppose the mirror is moving away from the light source at a speed of v in our frame of reference. Light strikes it at a speed of c-v. What is the speed of the reflected light? If the laws of reflection should hold (it’s not immediately obvious that they should), then the reflected light has to have a speed of c-v as well. This may explain why MMX gives null result. I haven’t worked out the whole thing though. I will, once I quit my day job and dedicate my life to full-time thinking. :-)

My idea is not a replacement theory for all of Einstein’s theories. It’s merely a reinterpretation of one part of SR. Since the rest of Einstein’s edifice is built on this coordinate transformation part, I’m sure there will be some reinterpretation of the rest of SR and GR also based on my idea. Again, this is a project for later. My reinterpretation is not an attempt to prove Einstein’s theories wrong; I merely want to point out that they apply to reality as we perceive it.

Overall, it was worth the $5 I payed. Thanks for the good read. Don’t take my questions as an assault on your proposal – I’m honestly in the dark about these things and I absolutely crave light (he he). If you could kindly answer them in your spare time, I’d love to share more ideas with you. It’s good to find a fellow thinker to bounce cool ideas like this off of. I’ll PM you again once I’m fully done the book. Again, it was a very satisfying read.

Thanks! I’m glad that you like my ideas and my writing. I don’t mind criticism at all. Hope I have answered most of your questions. If not, or if you want to disagree with my answers, feel free to write back. Always a pleasure to chat about these things even if we don’t agree with each other.

– Best regards,
– Manoj

Anti-relativity and Superluminality

Leo wrote:I have some problems with the introductory part though, when you confront light travel effects and relativistic transforms. You correctly state that all perceptual illusions have been cleared away in the conception of Special Relativity, but you also say that these perceptual illusions remained as a subconscious basis for the cognitive model of Special Relativity. Do I understand what you mean or do I get it wrong?

The perceptual effects are known in physics; they are called Light Travel Time effects (LTT, to cook up an acronym). These effects are considered an optical illusion on the motion of the object under observation. Once you take out the LTT effects, you get the “real” motion of the object . This real motion is supposed to obey SR. This is the current interpretation of SR.

My argument is that the LTT effects are so similar to SR that we should think of SR as just a formalization of LTT. (In fact, a slightly erroneous formalization.) Many reasons for this argument:
1. We cannot disentagle the “optical illusion” because many underlying configurations give rise to the same perception. In other words, going from what we see to what is causing our perception is a one to many problem.
2. SR coordinate transformation is partially based on LTT effects.
3. LTT effects are stronger than relativistic effects.

Probably for these reasons, what SR does is to say that what we see is what it is really like. It then tries to mathematically describe what we see. (This is what I meant by a formaliztion. ) Later on, when we figured out that LTT effects didn’t quite match with SR (as in the observation of “apparent” superluminal motion), we thought we had to “take out” the LTT effects and then say that the underlying motion (or space and time) obeyed SR. What I’m suggesting in my book and articles is that we should just guess what the underlying space and time are like and work out what our perception of it will be (because going the other way is an ill-posed one-to-many problem). My first guess, naturally, was Galilean space-time. This guess results in a rather neat and simple explantions of GRBs and DRAGNs as luminal booms and their aftermath.

Discussion on the Daily Mail (UK)

On the Daily Mail forum, one participant (called “whats-in-a-name”) started talking about The Unreal Universe on July 15, 2006. It was attacked fairly viciously on the forum. I happened to see it during a Web search and decided to step in and defend it.

15 July, 2006

Posted by: whats-in-a-name on 15/07/06 at 09:28 AM

Ah, Kek, you’ve given me a further reason to be distracted from what I should be doing- and I can tell you that this is more interesting at the moment.I’ve been trying to formulate some ideas and there’s one coming- but I’ll have to give it to you in bits.I don’t want to delve into pseudoscience or take the woo-ish road that says that you can explain everything with quantum theory, but try starting here: http://theunrealuniverse.com/phys.shtml

The “Journal Article” link at the bottom touches on some of the points that we discussed elsewhere. It goes slightly off-topic, but you might also find the “Philosophy” link at the top left interesting.

Posted by: patopreto on 15/07/06 at 06:17 PM

Regarding that web site wian.One does not need to ead past this sentence –

The theories of physics are a description of reality. Reality is created out of the readings from our senses. Knowing that our senses all work using light as an intermediary, is it a surprise that the speed of light is of fundamental importance in our reality?

to realise that tis web site is complete ignorant hokum. I stopped at that point.

16 July, 2006

Posted by: whats-in-a-name on 16/07/06 at 09:04 AM

I’ve just been back to read that bit more carefully. I don’t know why the writer phrased it like that but surely what he meant was:(i) “Our perception of what is real is created out of the readings from our senses.” I think that most physicists wouldn’t argue with that would they? At the quantum level reality as we understand it doesn’t exist; you can only say that particles have more of a tendency to exist in one place or state than another.(ii) The information that we pick up from optical or radio telescopes, gamma-ray detectors and the like, shows the state of distant objects as they were in the past, owing to the transit time of the radiation. Delving deeper into space therefore enables us to look further back into the history of the universe.It’s an unusual way to express the point, I agree, but it doesn’t devalue the other information on there. In particular there are links to other papers that go into rather more detail, but I wanted to start with something that offered a more general view.

I get the impression that your study of physics is rather more advanced than mine- as I’ve said previously I’m only an amateur, though I’ve probably taken my interest a bit further than most. I’m happy to be corrected if any of my reasoning is flawed, though what I’ve said so far s quite basic stuff.

The ideas that I’m trying to express in response to Keka’s challenge are my own and again, I’m quite prepared to have you or anyone else knock them down. I’m still formulating my thoughts and I wanted to start by considering the model that physicists use of the nature of matter, going down to the grainy structure of spacetime at the Plank distance and quantum uncertainty.

I’ll have to come back to this in a day or two, but meanwhile if you or anyone else wants to offer an opposing view, please do.

Posted by: patopreto on 16/07/06 at 10:52 AM

I don’t know why the writer phrased it like that but surely what he meant was:

I think the write is quit clear! WIAN – you have re-written what he says to mean something different.

The writer is quite clear – “Once we accept that space and time are a part of the cognitive model created by the brain, and that special relativity applies to the cognitive model, we can ponder over the physical causes behind the model, the absolute reality itself.”

Blah Blah Blah!

The writer, Manoj Thulasidas, is an employee of OCBC bank in Singapore and self-described “amateur philosopher”. What is he writes appears to be nothing more than a religiously influenced solipsistic philosophy. Solipsism is interesting as a philosophical standpoint but quickly falls apart. If Manoj can start his arguments from such shaky grounds without explanation, then I really have no other course to take than to accept his descriptions of himself as “amateur”.

Maybe back to MEQUACK!