By the silly block on Amazon

People nowadays are paranoid more or less --- more if you're a Linux user. Luckily it's really easy to disable web cam on a kernel module level. If

```
lsmod | grep uvcvideo
```

gives you some entries, you are good just to disable uvcvideo by:

`sudo`

]]>By the silly block on Amazon

People nowadays are paranoid more or less --- more if you're a Linux user. Luckily it's really easy to disable web cam on a kernel module level. If

```
lsmod | grep uvcvideo
```

gives you some entries, you are good just to disable uvcvideo by:

```
sudo modprobe -r uvcvideo
```

Where r stands for remove. On the other hand, if you want to make this permanent:

```
sudo vi /etc/modprobe.d/blacklist.conf
##add a line
blacklist uvcvideo
```

This will instruct the kernel to unload the module that is being used to drive the web cam, which means that unless attacker has root privilege, you're fine. (I don't see why they would record a video of you if they have root access).

When you do so, if you want temporarily enable the module, you can ask modprobe to do so:

```
sudo modprobe uvcvideo
```

]]>Unlike classical (Newtonian) mechanics where there seem to be a very intuitive and wildly accepted approach of learning, quantum mechanics can be introduced through various proxies and people can learn it as either:

- Tricky model inspired by Black body radiation + Sketchy assumption
- or, Elegant (but hard to solve) equations that follow axioms of quantum mechanics.

In this 2-parts note, I will write myself a note that is most clear and logical for what I have learned so far.

For this reason, I will introduce equations and relevant mathematical tools as granted, of course with reference for them.

If I were to use one sentence to summarize Schrödinger equation (call it [SE] form now on):

**Complex number wave function $ \Psi (x,t) $ tells your probability amplitude about the particle.**

This is called statistical interpretation, it does not always work, but for elementary usage of [SE], we almost can always have this image in back of our head.

Now, $\Psi$ is not straight **probability** because it's a complex function, to get probability you will need to give it its own conjugate, naively:

$$

P(x,t) = \Psi^*\times\Psi

$$

As for the reason why it has to be a complex-number function in the first place, is because if your think about $e^{i\theta} = \cos{\theta}+i\sin{\theta}$, you will see you some what need a complex function to fully express a wave function across space and time.

Knowing how we should look at $\Psi(x,t)$ (which is just a 1-D case but it's okay), we can look at 1-D [SE] which the wave equation $\Psi$ promised to satisfy:

$$

-\frac{\hbar^2}{2m}\frac{\partial^2\Psi(x,t)}{\partial x^2} + V(x,t)\Psi =

i\hbar \frac{\partial\Psi(x,t)}{\partial t}

$$

Here, $\hbar$ is reduced Plank's constant, $m$ is mass of the particle and $V$ is the potential. Also bear in mind that it's a **complex number equation**.

We tend to think free particle solution is the simplest solution to look at but turns out that has a vague physical picture, so we look at particle in a box solution first.

But above all that, we need to invoke a mathematical (proof) that the solution is separable, meaning that $\Psi(x,t) = \psi(x)\varphi(t)$. You see physicists make this separable argument a lot, this is because they will later rescue it by proving that all such solutions combined can provide a complete solution set.

Given separable, we immediately can re-range the [SE] to get:

$$

i\hbar \frac{1}{\varphi(t)} \frac{d\varphi}{dt} = -\frac{\hbar^2}{2m}\frac{1}{\psi(x)}\frac{d^2\psi(x)}{dx^2} +V

$$

This suggest that left and right both equal to a constant because they are independent in variables, we will suggestively give this constant $E$. So far we have turned a two-variable ODE into 2 one-v ODEs:

$$

\begin{cases}

\frac{d\varphi}{dt} = \frac{iE}{\hbar}\varphi \rightarrow \varphi(t) = e^{-iEt/\hbar}\\

-\frac{\hbar^2}{2m}\frac{d^2\psi}{dx^2} +V\psi = E\psi \rightarrow ?

\end{cases}

$$

It turns out the second one is hard to solve (easy once you know the answer of course, it's all about tricks). The take way is, once we solved it, we will get:

$$

\Psi(x,t) = \sum_{n=1}^{\infty} c_n\Psi_n(x,t) = \sum_{n=1}^{\infty} c_n\psi_n(t)e^{-iE_nt/\hbar}

$$

Where you can see that the **time** term is snaped onto the **spacial** term. And all of different allowed $E_n$ will give any valid general solution.

Now we consider particle in side a region that is walled by infinite potential outside:

^{[1]}

This has the convineance that potential $V=0$ inside, and we must have $\Psi=0$ out side the box (because otherwise energy explodes). Another way to look at it is that, if we know there's a particle somewhere and we accept the said interpretation, we will expect:

$$

\int_{-\infty}^{\infty}|\Psi|^2 dx = \int_{-\infty}^{\infty}\Psi^*\times\Psi dx =1

$$

Because there **is** 1 and only 1 particle in our set-up. Plus the fact that $\Psi$ should be continuous otherwise we will have different probability of spotting the particle approaching from left or right, which is un-physical. Given these 2 conditions, easy to see that out side the box, probability of finding particle must be zero and also $\psi(x=0)=\psi(x=L)=0$. This is **boundry condition (b.c.)**

We can focus on solving spatial part $\psi(x)$ because we can snap the time term easily later. The spacial solution is just some wave form, we look at:

$$

-\frac{\hbar^2}{2m}\frac{d^2\psi}{dx^2} = E\psi

$$

and write $k=\frac{\sqrt{2mE}}{\hbar}$ so $\frac{d^2\psi}{dx^2} = -k^2\psi $.

This is obviously a ODE with solution:

$$

\psi = A\sin{kx} + B\cos{kx}

$$

Up bring **b.c.** into it, we see that $B$ must goes to 0. Then because at $x=L$:

$$

A\sin{k L} = 0

$$

we have $k_n=\frac{n\pi}{L}$ which are discrete allowed values. From these allowed $k$'s, we can see that energy is also discrete because:

$$

k=\frac{\sqrt{2mE}}{\hbar} \rightarrow E_n=\frac{\hbar^2k_n^2}{2m}

$$

Then we have a whole set of solutions with different energy and wave-form, the general solution will be any combination of them:

$$

\Psi(x,t) = \sum \Psi_n(x,t) = \sum \psi_n(x)\varphi_n(t) = A\sin{k_n x}e^{-iE_nt/\hbar}

$$

$A$ will need to be found by normalizing this, but it shouldn't be too hard. Finally, to visualize what these different solutions mean:

^{[2]}

Notice that energy goes higher, and the form of the wave function itself actually looks like standing wave on string. But remember that probability comes from $|\Psi|^2$ not this wavefunction.

Banner from Evangelion 2.22

It's rough to study PHYS 125 here without actually systematically studies Q.M. first. But I will give a shot and preview Dirac Equation (essentially a relativistic Schrödinger equation) here and write a summary for its key features.

In general, Schrodinger's equation refers to

]]>Banner from Evangelion 2.22

It's rough to study PHYS 125 here without actually systematically studies Q.M. first. But I will give a shot and preview Dirac Equation (essentially a relativistic Schrödinger equation) here and write a summary for its key features.

In general, Schrodinger's equation refers to the following, and we most will only deal with it's 1-D form.

$$

i \hbar \frac{\partial}{\partial t}\vert\Psi(\mathbf{r},t)\rangle = \hat H\vert\Psi(\mathbf{r},t)\rangle

$$

Following Griffiths Chapter 7, we shall see what happens is the mean speed of the particle is too fast that momentum requires relativistic correction.

After familierizing oneself with the concept of operators and how we can obtain observables by combining (H, x, p) operators according to classical formulas, we can use this machinenary to 're-derive' Schrodinger's equation. First, recall a *classical* energy-momentum relation:

\begin{equation}

\frac{\mathbf{p}^2}{2m} + V = E

\end{equation}

Apply what Q.M. taught us about observable (p) being a operator:

$$

\begin{cases}

\mathbf{p}\rightarrow-i \hbar\nabla \\

E\rightarrow-i \hbar \frac{\partial}{\partial t}

\end{cases}

$$

And apply the whole equation (as an operator), on a wave equation $\Psi$, we get Schrodinger's equation:

$$

-\frac{\hbar ^2}{2m}\nabla^2\Psi + V\Psi = i\hbar\frac{\partial\Psi}{\partial t}

$$

KG equation can be obtains by the very same logic --- using Q.M. operators to replace some variable in classical formulas and see where it leads us to. From relativity, we know that $E^2 - p^2c^2=m^2c^4$ (I want to let $c=1$ so badly). Of course we are neglecting potential energy here because we are dealing with particle physics. We can also write this in more informative **Einstein notation** :

$$

p^\mu p_\mu - m^2c^2 = 0

$$

If now we replace each $p_\mu \rightarrow i\hbar \partial_\mu$, with $\partial_\mu=\frac{\partial}{\partial x^\mu}$ (you can never be too familiar with co/contravariant). We can write out a bit just to be clear:

$$

\partial_0=\frac{1}{c}\frac{\partial}{\partial t},\partial_1=\frac{\partial}{\partial x},\partial_2=\frac{\partial}{\partial y},\partial_3=\frac{\partial}{\partial z}

$$

We can drag all of these into our original relativistic energy-momentum equation:

$$

-\hbar^2\partial^\mu\partial_\mu\psi - m^2c^2\psi = 0

$$

or it's equivalent to write as:

$$

-\frac{1}{c^2}\frac{\partial^2\psi}{\partial t^2}+\nabla^2\psi = (\frac{mc}{\hbar})^2\psi

$$

Which is the KG equation. Schrodinger actually discovered this before the non-relativistic one and abandoned it because it failed to reduce to Bohr's model (because electron is fermion and KG equation is in fact for Bose-Einstein statistical particles).

Recently we have added $\LaTeX$ functionality (again) to this blog, and to demonstrate (show off) the easiness comes along, I shall write a short class note on the Principle of least action - from from physical analysis and mathematical exploration point of view.

The way we think about '**action**' is a bit abstract. We know from middle school physics that $\vec{F} = m\vec{a}$ and work, as a consequence of motion along direction of force, is:

$$

dW = \vec{F} \cdot d\vec{x}

$$

**Action** is similar to work, but the integrand of action is *Lagrangian* $\times$ *Time*. Least action simply means, mechanical systems evolves so that the action is minimized (in fact we just need it to be a statinary point). Which mathematically would look like:

$$

S = \int_{t_1}^{t_2} \mathcal{L}dt

$$

Where * Lagrangian* $\mathcal{L}= T-U$, kinetic energy $-$ potential energy of the system.

One way of getting your head around the concept of **action** is to make sense of d'Alembert Principle first.

We shall start doing so by defining a few terms:

**Degree of Freedom**: any particle has 3 degree of freedom in vacumn, but constrains imposed to them might reduce that number. If we have a system of N particles, we shall have 3N degree of freedom without constrains.**Constrains**and constrains force: Think of these as an extened catagory of normal force, they are there to prevent objects to move into certain direction, and their magnetude depends on the situation given.**Virtual displacement**: $\delta\vec{r}$ is a vector of displacement. Imagine you freeze the time when a particle is traveling along a trajectory, now you imagine the particle is $displaced$ from its original path, that imaginary displacement can be expressed using this virtual displacement vector.- Virtual work $\delta W = \vec{F}_\text{total} \cdot \delta\vec{r}$

Now consider some particle going under some motion, we can denote the position of the particle $\vec{r}(t)$ for any moment in time. This is the **true path** of the particle, now imagine instead we let the particle to travel through a near-by trajectory instead the **true path**, we can express the new trajectory by:

$$

\mathbf{R}(t) = \vec{r}(t) + \vec{\epsilon}(t)

$$

Where $\vec{\epsilon}(t)$ goes from point on the true path to point our near-by path at any given moment.

Since the particle is going on a specified trajectory, we say it is constrained. The easiest way to depict this is to imaging a frictionless bob sliding on a curved surface. Now we want the near-by path to be a physically possible path, which means that $\vec{\epsilon}(t)$ has to be consistent with the constrains given. In our imaginary case of bob sliding on a surface, we can easily see that $\vec{\epsilon}(t)$ has to be parallel to the surface at any given moment. (Otherwise the particle either goes into the surface or fly away from it).

Recall the definition of the **action** and express *Lagrangian* using parameters we just defined:

$$

S = \int_{t_1}^{t_2} \mathcal{L}(\mathbf{R},\dot{\mathbf{R}},t)dt

$$

We want to show this integral is *stationary* respect to the change of $\vec{\epsilon}(t)$ when the path $\mathbf{R}$ is the **true path** we started with. Thus

$$

\delta S=S-S_0

$$

From here we can see that upon substitution and evaluation:

$$

\delta \mathcal{L} = \frac{1}{2}m((\dot{\mathbf{r}}+\dot{\mathbf{\epsilon}})^2-\dot{\mathbf{r}}^2)-(U(\mathbf{r}+\mathbf{\epsilon},t)-U(\mathbf{r},t)

$$

One (and the simplest) way of getting to equations of motion in Hamiltonian mechanics is through calculus of variation. It is illuminating enough to consider 1-D senario at the beggining, since the higher dimensional case merely needs adding summation. First, we know that by definition:

$$

\mathcal{H} = p\dot{q} - \mathcal{L}

$$

where $q$ is generalized coordinates and $p$ is the corresponding generalized momentum. Of course, $\mathcal{L}$ is our old friend *Lagrangian* $\mathcal{L}(q,\dot{q},t) $.

Then, if we consider imposing variation on $q$ and $p$ so that, if we denote the true path of them as:

$$

\begin{cases}

q(t)\\

p(t)

\end{cases}

$$

We can impose also a variation on them:

$$

\begin{cases}

q_\alpha(t) = q(t) + \gamma_\alpha(t) \\

p_\alpha(t) = p(t) + \gamma^\prime_\alpha(t)

\end{cases}

$$

Here, we can thing of $gamma$'s as the difference between true path and altered path at any given time. If our system begins at $t_1$ and ends at $t_2$, we naturally have:

$$

\gamma_\alpha(t_1) = \gamma_\alpha(t_2) = 0

$$

Because the two ends are known to us. Now, by definition of action, we see that the variation of action is:

$$

\delta \mathcal{S} = d\alpha \frac{\partial}{\partial \alpha}\int_{t_1}^{t_2} dt \mathcal{L} = d\alpha \frac{\partial}{\partial \alpha}\int_{t_1}^{t_2} dt \left[ p_\alpha\dot{q}_\alpha - \mathcal{H} \right]

$$

Now we want to move the partial derivative into the integration because the variation we impose is not related to time, also bear in mind that the partial derivative would hit term and we will be using chain rule here:

$$

\begin{split}

\delta \mathcal{S} &=d\alpha \frac{\partial}{\partial \alpha}\int_{t_1}^{t_2} dt \left[ p_\alpha\dot{q}_\alpha - \mathcal{H}(p,\dot{p}) \right] \\

&=d\alpha\int dt \left[ \frac{\partial p_\alpha}{\partial \alpha}\dot{q}_\alpha +

p_\alpha\frac{\partial \dot{q}_\alpha}{\partial \alpha} -

\frac{\partial \mathcal{H} }{\partial q_\alpha}\frac{\partial q_\alpha}{\partial \alpha}-

\frac{\partial \mathcal{H}}{\partial p_\alpha}\frac{\partial p_\alpha}{\partial \alpha} \right]

\end{split}

$$

Then if we apply inverse by parts to the second term in the bracket, we see that:

$$

\int_{t_1}^{t_2}dt p_\alpha\frac{\partial \dot{q}_\alpha}{\partial \alpha} =

\left[ p_\alpha\frac{\partial q_\alpha}{\partial \alpha}\right]_{t_1}^{t_2}-

\int_{t_1}^{t_2}dt\dot{p}_\alpha\frac{\partial q_\alpha}{\partial \alpha}=0-\int_{t_1}^{t_2}dt\dot{p}_\alpha\frac{\partial q_\alpha}{\partial \alpha}

$$

The term evaluated to zero because we know the ends have no variation.

Plug this result back into the original integration we see that:

$$

0=\delta\mathcal{S}=d\alpha\int dt \left[

\frac{\partial p_\alpha}{\partial \alpha}\dot{q}_\alpha -\dot{p}_\alpha\frac{\partial q_\alpha}{\partial \alpha} -

\frac{\partial \mathcal{H} }{\partial q_\alpha}\frac{\partial q_\alpha}{\partial \alpha}-

\frac{\partial \mathcal{H}}{\partial p_\alpha}\frac{\partial p_\alpha}{\partial \alpha} \right]

$$

If we re-group terms with the same partial derivative together, and argue that since those derivative are not necessariley zero, we must have:

$$

\begin{cases}

\dot{q} = \frac{\partial \mathcal{H}}{\partial p}\\

\dot{p} = - \frac{\partial \mathcal{H}}{\partial q}

\end{cases}

$$

Which is what we wanted.

Isn't able to estimate the covariance of the parameter, thus raising the OptimizeWarning below

Scipy Curve_fit

Today's lab ran into a problem that when people try to fit a function with

exponential and square root in it, the results is either off, or the

prameter does not work.

The problem is that if the fitting function tries to go through `undefined`

points in your function, it throws out the warning above.

The importance of guessing is discussed in this thread, but the gist of it is, when fitting, use `p0`

argument to give initial point for fitting.

```
popt, pcov = curve_fit(func2, np.arange(10), np.arange(10), p0=(0, 0))
```

]]>As the winter quarter is coming to an end, I think it is the time that I start writing in report/review style entries that will serve both as record and reminder for me.

In terms of classes, there are still many to be fulfilled. But our CCS track intro classes is coming to an end next quarter, with it, also the 15A/B/C sequence.

However, due to other reasons, I shall be trying to take a upper particle physics class --- a class that I will need to learn in advance to catch up.

Other thank losing my whole key chain 2 days ago, I think it is an exciting part of my college life: just entered research group where tons of stuff awaiting, life is getting in order and classes are fairly interesting. Couldn't ask more :p

GRE and PhD application worry me more than any short term thing.

About the research group. Every physics student had dreamed about becoming a particle physicist --- experimental or theoretical. I, also, could not let the chance go away even though my Professor/Advisor Sathya has repeatedly 'implied' other wise.

I really like the atmosphere of our group and the whole high-energy physics community. Despite the complexity, people work carefully and open-sourced-ly in the community.

Our group, for the moment being, has 2 parts (I think). One is a long-term hardware project milliQan, the other one includes all

the LHC/simulation data-driven work that our PhDs are doing. These data-driven work

mostly aim to increase efficiency of finding events in the detector, where efficiency means valid data / total collision ratio. As the HL-LHC goes along, there

will be some space for improvements.

Writing this down without explaining them makes me want to write a separate article.

]]>1999年是一个平年，第一天从星期五开始。^{[1]}

1999年被联合国指定为国际老人年。

欧元正式流通

哥伦比亚地震

Family Guy 开播

约旦国王病逝

Bill Clinton无罪释放

Melisa 病毒

科索沃战争

黑客帝国上映

Bill Gates 成为世界首富

北约在科索沃战争中误判轰炸难民车队

外界称为中国最大规模的理性和平上访

星球大战前传上映

蓝牙技术问世

在修复22年后首次在意大利, 米兰展出

1420 空难

不丹王国首次允许电视广播

开始取缔邪教

MSN 初版

Lunar Prospector 撞击月球表面完成设计使命

第二次车臣战争

苹果发布G4个人电脑

- GPS 周计数归零

Sonic Adventure问世

台湾921大地震

上海浦东机场开始接管所有国际航班

50周年阅兵

美国参议院否决承认禁止核试验合约

埃及航空990空难

神州系列第一支火箭升空

中国正式开始与美国就加入WTO开始双边会谈, 2001年正式加入

ExxonMobil合并完成, 成为世界第一大企业

Tori Murden, 第一个以皮划艇穿越大西洋的女性

澳门特别行政区成立

美国将巴拿马运河主权交还巴拿马

叶利钦辞去职务, 总统普京首次就任代总统

- 1999年的最后一天是一个星期五。

Dante depicts a vivid hell in the *Inferno* and, by doing so, expresses his worldview and theological arguments in a very poetic way. As a poet after Augustine’s era, Dante’s depiction of the world and the hell contains many traces of the Augustinian theology. For example, Dante recognizes

Dante depicts a vivid hell in the *Inferno* and, by doing so, expresses his worldview and theological arguments in a very poetic way. As a poet after Augustine’s era, Dante’s depiction of the world and the hell contains many traces of the Augustinian theology. For example, Dante recognizes the limits of human reason and the merciful nature of God’s love and writes about these themes in the *Inferno*. Yet, Dante’s the *Inferno* is also creative and different from Augustine’s ideas: it levels human to a more active position by connecting people’s doing when they are alive to their destinations in the after-life.

Like Augustine, Dante ranks the evilness not according to moral instincts people may easily think of, but according to how much does the evilness go against the natural order, in other words, God. The arrangement of three rings in the 7th circle of hell in the *Inferno* serves as an evidence. Suffering from the boiling blood and eaten by the Harpies are the punishments for violence against neighbors and oneself respectively in first two rings (*Inferno* XII.46-48 & XIII.100-102). However, even tyrants like Pyrrhus, Sextus only suffer the slightest pain in the 7th circle as they submerge in the boiling blood. Underneath them are people who harmed themselves when they were alive – they mostly did not even affect others’ lives. This feature stands out because the Bible does not explicitly condemn suicide more than murdering others. Arguably, Dante is making a distinction here according to the motivations: murders are often motivated by explicit reasons such as greed or violent nature, but suicide is about mistreating life (humans) created by God and is more against the natural order. This argument is also supported by the third ring in the 7th circle, in which souls of people who were violent against God but are not heretics, are suffering from the burning sand and falling flames (*Inferno*. XIV.28-30). Sins committed by people in this ring is the worst because even they did not impose wrong ideas on others, they sinned against God in their heart. The sin of the third ring is also the most ‘internal’ one among 7th circle: knowing God but disdain him is a personal matter but is worst in Dante’s view (*Inferno*. XIV.70-72). Overall, this ranking by faith and relation to God has a high level of concordance with the Augustinian theology.

Dante also emphasizes the idea that punishments are eternal and continuous in the hell. This idea is similar to the idea of eternal harmony and happiness in the heaven by Augustine, but instead, Dante’s narrative is about the hell. In the outermost cycle of the hell, Limbo, people who were born before Christ are punished by having no hope in knowing God (except for when the Harrowing of Hell happened, *Inferno* IV.40-42, 55-57). Unlike the purgatory, punishments in the hell do not wash away these souls’ sins and there is no way for souls to escape from suffering in the hell. For example, in the 4th circle of greed, people are divided into two groups and are wheeling weights against each other forever (*Inferno*. VII.28-30). This is, by Dante, the opposite of the great harmony in the heaven: people in the hell repeat tasks and torments forever without any progress. In Dante’s hell, people suffer endless yet rational pain for what they did earlier in the life. Thus, the eternal pain is the counterpart of the eternal harmony in the heaven.

The biggest difference between Dante and Augustine’s views is of the role played by humans in the process. Unlike Augustine who recognizes human as very incapable and whose destination is solely dependent on God’s plan, Dante has a more detailed idea about the process. The structure of the hell can be traced back to ideas of Aristotle. Yet, the fact that hell can be divided into upper and lower portion is an evidence that Dante thinks the nature of the sins is a critical part that needed to be addressed. The upper hell, from the Limbo to the 5th circle, contains souls of people who failed to regulate their sinful nature in the world above; the lower hell, from 6th to 9th circle, is for those who willingly committed sins. The same kind of cause-and-effect relationship can also be seen in a smaller scale, for example, how deep one is in the boiling blood is related to the degree of violence he/she committed (*Inferno*. XII.73-75, 103-104). This suggests that Dante thinks people can reduce suffering in the hell simply by doing fewer sins when alive. This worldview certainly has more room for human agency compared to Augustine’s – it allows one to actively be a better version of oneself.

Allowing human’s doing to determine where souls go in after-life does not mean Dante belittles God. In fact, just like Augustine, Dante recognizes clearly the limits of human reason and the theme occurs multiple times throughout the *Inferno*. Dante, for he is a living man, frequently seeks help and support from his teacher Virgil throughout the trip in the hell. (*Inferno* VIII.97-99) However, even Virgil, who commands Centaur Chiron to send guards in the 6th circle (*Inferno* XII.85-97), could not pass the gate of Dis that is guarded by fallen angels until the arrival of help from Heaven (*Inferno* VIII.82-84 & 118-120). This series of events can be interpreted as Dante is describing the limits of human reason. Dante can do the least because he is the only living one in the hell and his humanity fears a lot. Virgil, as Dante’s guide in soul form, is more capable: he constantly giving Dante confidence and convincing monsters in the hell to make ways for them. Importantly, Virgil does so by emphasizing that their trip is promised by God and thus shall be permitted – it is not that Virgil has power or authority, instead, he is using the authority given by God. But at the gates of Dis, Dante and Virgil encounter fallen angels. These angels rebel God willingly, thus authority by God does not convince them in any way. This is the limit of human – despite Virgil being a great guide for Dante, he could not stand against angels by his human reason. As a solution, Heaven sends help directly to make ways for these two travelers for their faith in Christ and calling (*Inferno* IX.7-9). This is Dante’s way of showing God’s authority is the ultimate and that he is mercifulness over limited humans.

In conclusion, Dante’s description of hell adapts most of the Augustinian theology and is largely based on it. In the *Inferno*, Dante demonstrates how the ranking of evilness is not what people may usually think, but is closely related to how faith-denying a sin is. Moreover, he realizes the limits of human just like Augustine and expresses it through Dante and Virgil’s action during their trip. But Dante is also different from Augustine that he depicts the eternal suffering as a rational counterpart of what people sinned in the above world, which gives humans a compelling reason to do good while alive.

回到上海已经十天了，不知不觉间发现自己和家乡格格不入。

人其实很容易发现自己和世界不兼容：当白领们辛苦工作只想在周末过和你躺着一样的生活、综艺频道是收视率最高的但你却一集都没看过——大众的平均值是一种很微妙的东西，确实有很多人方方面面都被平均值代表，但不少人又发现自己在边边角角上总有异类之处。

开始用数据和平均值去看待和解构世界是长大和变得不浪漫的一个标志。我二年级到初中住的地方，客厅的一面落地窗正对着花园，花园上方是二楼阳台；二楼反方向走廊尽头是书房，书房的窗户隔着小区里的路面对对面的人家。那是个没有智能手机，家长也不允许我晚上打游戏的时间，单亲母亲有时候会带我去家附近的商场吃饭，饭后回家家里总是漆黑的，只有进门玄关处的灯和窗户附近墙面上的防盗感应器会幽幽闪烁。这个时候从家中任何一处窗子往外望去，都能看到小区里别家的光景：厨房的烟，电视的荧光，抑或餐桌旁起伏的人影。

我经常看得入神，甚至有时候故意关掉灯，只为了消除玻璃上的反光。我想那儿时的心情可以用浪漫形容，那是把自己带入别人生活的一种浪漫，是相信每个人都过着值得被关注的生活的人本主义浪漫。现在回过头总结，我会把那时候的心情归因于好奇：因为儿时的我们不知道生活的重复和千篇一律，才一厢情愿地认为他人，或者任何人，的生活有其特殊性。我记得那时候我最好奇花园正对面一对老夫妇的家，他们的厨房对着我们花园，在他们车库的上方，里面的柜子用上了华丽的珠黄大理石花纹，车库里也永远有明亮的白炽灯和堆放在两侧的东西。

我刚刚回到家，11点半，郊区上海的夜间喧嚣还没有完全安静下来。今天和家里经历了尴尬的一天，所幸我熬到大家都睡了才推开家门——不同的家，一样的玄关白炽灯，一样的花园落地窗。透过花园前的灌木丛，我能看到对家的电视在播放着些什么，但是人再也不会关心别人家电视在什么，他们家的孩子看得开心吗？人更多地是被唤起孤独与平庸感，发现自己只能平行地去比较自己和他人，而无法再真诚地把自己想象进入别人的日常生活——因为终于我们发现大多数人只是活着，而别人的生活也没有目的性可言。更重要的是，生活中信息量的急剧增加，让我们不得不把别人的生活平均抽象成无聊的背景音。

我很想念缩在书房沙发上，把头搁在窗沿，黑着灯看着外面几十扇窗里几十家人不同的生活，然后想：明天所有人一定都会精神满满地开始新的一天吧。想再在这种幻觉中安心睡觉，可能是我对童年怀念的本质了。

]]>Cover is the world famous The Conversion Of Saint Augustine by Fra Angelico.

In the *Confessions*, Augustine wrote extensively about human’s and God’s role, evil, and sin. According to his writing on these subjects, it is evident that Augustine believes humans to be incapable of doing good; we

Cover is the world famous The Conversion Of Saint Augustine by Fra Angelico.

In the *Confessions*, Augustine wrote extensively about human’s and God’s role, evil, and sin. According to his writing on these subjects, it is evident that Augustine believes humans to be incapable of doing good; we cannot judge good from bad, nor achieve anything truly great without crediting to god. However, according to him, our incapability does not imply that humans cannot be Christian. He thinks God is what defines good and, in fact, there is no way for humans to ‘become’ Christian. According to Augustine’s writing, it is not human agency but God’s grace decides if one is Christian or not.

Augustine thinks only Divine agency can define good and bad, and humans are incapable of doing truly ‘good’ things on their own. First, in* Book III Chapter 8 & 9* he quotes from Matthew saying that to ‘love God with whole heart is never wrong’ and that ‘sins against nature’ are wrongdoings, for example, the sin of Sodom. Moreover, he emphasized that secular power such as Kings and states must conduct the rules of Christianity unconditionally with priority. This implies Augustine’s view that no matter what we do, or how a kingdom is ruled, all must follow the law in heaven as that is the truly correct law. Moreover, earlier in *Chapter 7 of Book III*, he argues that law of Almighty God is always ‘equitable and never changes from age to age nor place to place’ yet can ‘suit’ to different needs in different places and ages. Augustine explains this saying that all the changes and adaptations form a harmony at a higher level that no one can see.

Though Augustine does not provide a direct following in the same Book, arguably according to his view, human agency (even the King) is not competent to decide what is correct and wrong.

On the other hand, Augustine thinks God, unlike human agency, has the greatest authority in deciding what is ‘good’ and in fact itself all good. Augustine describes a few examples of the nature of evil through metaphors and stories in the *Confessions*. In Book I Chapter 7, he argues that since no one would get rid of good habits, and since infants would stop crying for things they want once they grow up, it proves that infants carry sins just as he describes earlier in the same chapter: ‘not even a child who has lived only one day on earth (is not sinful).’ Also, he uses himself as an example in *Book II Chapter 4* – he robbed a pear-tree and only enjoyed the sin of theft itself but not the pears.

The two examples he used above in the *Confessions* elaborate two critical characteristics of his view on sin and human nature:

- sin has nothing to do with self-awareness and intelligence as the infants lack both
- and, sinful nature lies ‘deeper’ than merely bad intentions, rooted deeply in everyone

With these two concepts in mind, it is natural for Augustine to argue further that the only reason he did not commit more sins is that he was guided by God’s grace; and no effort of curing weakness made by man can be effective unless by God’s grace (*Book II Chapter 7*).

Augustine takes a step further on this idea – he argues that not only God’s grace decides how well a man can keep himself away from sin but in fact, everything done by humans can be judged by how much faith they hold for God. In*Book V Chapter 3*, Augustine explains why accomplishments of astronomers are not as legitimate and cannot be ‘preserved’ since they did not credit the discovery to God nor utilize Christian faith when conducting calculations. Similarly, he makes a point in Chapter 4 of the same Book that knowing God is the greatest good and happiness and that none of the secular knowledge such as astronomy can play the slightest role in the process. These arguments implied that Augustine thinks the major factor in determining good or less good is not by human reason and perspective but by Divine agency.

Naturally many may think Augustine is extreme, yet it would be less so once we look closely at what he thinks about the nature of ‘evil’.

In*Book VII Chapter 3 and 5*, Augustine goes through all the questions and concludes that since God is omnipotent and is what defines good, there should be no evil nor seeds of evil in his creation. Thus, Augustine goes on and reasons in Chapter 12 that all entities and actions that exist are ‘good’ ¬¬¬– because God is the ultimate source of them all – and it is our limited vision of the bigger picture That leads us to think evil exists. The consequence of this worldview is clear – it makes humans seem even more incapable in the big picture because we cannot fight original sin and there is no such thing called evil in the first place for humans to resist. This view greatly diminishes the meaning and purpose of our daily activities other than prying as things we do out of our own consideration would be sinful and not helpful in reducing ‘evil’ as it does not exist.

It can be concluded using Augustine’s word in*Book X Chapter 28*: ‘no hope for me except in your great mercy (grace)’. It is not hard to see why many initially may think Augustine fails to address ‘what we should do to become Christian’, for Augustine did not look at the world in this way, at all. Augustine holds human reason and factors very low and uninfluential in the weighing scale of right and wrong. He decides that we cannot do good on our own in the first place. Instead, Divine agency rules the ‘value judgment’ in this process and ‘gratuitous’ grace given by God is the only out from sinning and only guidance for humans to true goodness. He takes the Christian faith as a consequence of the weakness of human agency, thus needless to talk about ‘what we should do to become’ at all. In short, the*Confession*takes a different approach by defining ‘good’ out of the scope of moral instincts and put the relationship between us and Divine agency in a complex way such that becoming ‘Christian’ itself is a consequence of God’s grace.

我十几岁的时候特别不能接受家中晚餐桌上的美国式平等，那时候我刚刚和重组家庭开始在除了周末以外的时间一起生活。我的义兄当时（现在依然）是个很非典型的人——不说他只会讲英语和上海话，也不是说他是美国人这一点很特殊。要一个中国家庭培养出这样一个孩子几乎是不可能的，在我的假象场景下，我哥这样的性格会被贴上的标签有：长不大，疯疯癫癫 etc.

但这都不是太重要，我依然相当喜欢他的（我10个小时前还在和他打DotA），我想说的是在当年他比现在还孩子气的时候，浓缩表现在我们家餐桌上的美国式平等理念。

说起平等，人会不自觉地开始考虑哲学，特别是政治哲学里，这个词的意义。我不打算概述政治哲学对“人生而平等”这句话上百年来的讨论演进，但我认为有几点需要强调：

- 人对平等的概念几乎是 self-evidently clear 的，绝大多数正常生活长大的人，都会觉得自己对平等这个概念有相当程度的理解。
- 平等(equality) 不是【相同】，人生而有不同性别，升高，肤色，这是不同
- 平等在实践中的本质是"改造平等"，平等不是自发的，而是: 不平等->提出问题和方案->解决不平等

第一点和第三点导致发达国家的社会里，不同诉求和价值观的人会自发去游行抗议说服立法者，因为他们认为他们找到了不平等的关键和解决方案。第二点，依据人不同的价值观，可以扩张到有争论的地带，比如出生时的家庭环境，比如家长的教育水平 etc. 在这些问题上的争论几乎没有食指进展。

回到我家餐桌和美国式平等这件事上，美国政治语境里的平等被规范成了一个更准确的【机会平等】，与之相对的是【结果平等】。这个很好理解，考试就是一种【机会平等】的过程，所有人不可能最后都拿到平均分，但我们假设学生从老师那里能获取到的资源是平等的。这个话题其实有更多细节可以追究，比如说有钱的学生可以补课？没钱的学生需要花课外时间去打工？这些问题也确实是目前美国学生助学金机制存在的一大动机。（所以才说美国先进吧大概 笑）

这些动机都是好的，事实上假如真的有我们感性上认识的一种状态叫做平等，那它怎么看都是好的。然而问题的关键就是，就算我们明确了希望【机会平等】，社会的强弱群体之间依然无法调和，这里回到我家餐桌举例。

我那时候最最烦的事情就是和家里一起吃饭，特别是在家吃饭。具体原因有一二，**一**是当时我英语水平拙计，想要听懂他们在说什么会影响食欲；**二**是义兄妹的挑食让我总吃不到好吃的。你们都看出来了，重点显然是**二**。

重组家庭里我和父上是比较无所谓的那方，谈不上弱势但中国家庭传统上家里都比较默契吧，至少假装有默契所以不会太积极地对一些家庭琐事过多参与。美国家庭喜欢，**交流**，就是大事小事都要说的那种；所以我家从外部看起来是后母和义兄妹强势的情况。

在这个前提下，义兄挑食具体是什么样的呢：比如晚饭有一盘番茄炒蛋，桌上4个人，他一个人还没开饭就掳走半盘。先不说这个在中国的餐桌礼仪上就说不过去，我们假装这是文化差异，但从实际角度上，我们桌上剩下三个人该怎么反应呢？类似情况发生的频繁程度让我有一天忍不住和家长抱怨，但我得到的回答是：因为我不挑食，所以吃什么都可以，义兄挑食如果不吃就没得吃了所以我们得让着。我肯定接受不了这种强盗逻辑，合乎如果我也挑食我就可以和义兄打起来了？事实上我觉得当年家长确实是这样想的，但我自己无法接受故意闹别扭去抢吃的这么幼稚的事情，所以忍了接下来的几年。

只看餐桌这个具体的例子其实问题很好解决，提前知道义兄吃什么的家长把那饭菜多烧一点就解决了。但在直到今年还在上演的美国社会运动里，我看到的是一个又一个我家餐桌的放大版：少数人性别认同要去对方的厕所，大闹，成了；大学里教希腊历史，黑人学生说这是种族歧视，在教室里静坐，成了；加州差一点通过SAC-5 etc. 美国社会在一些社会问题上一而再再而三地证明，哭得大声有奶喝这样一种本应是错误的情况。这种事实的可理解性在于，这是管理者最不需要花费精力的一种策略，假设哪里不平等哪里就有抗议，那么既然平等无法直接衡量，执政者的本质是解决抗议（不是某大国那种解决）。

另外一个问题是，【机会平等】的机会，到底哪里是起点。这里我们举例美国大学录取，大学录取近年来对黑人，西裔有优惠，对白人和亚裔有歧视。对亚裔和白人的歧视根源其实是不同的，但我们先讨论对黑人和西裔优惠这件事，大学方面的观点是，因为黑人和西裔群体常年来社会资源不好，导致几代人缺少教育，所以给予【机会平等】让他们可以从大学重新起步。反方观点常见的是，机会早在初中，高中的优惠和助学项目里体现了，大学作为高等学府，录取低于及格要求的学生，不仅伤害大学生群体，更是对没有被录取的别的族裔的学生的歧视。

这里我不想讨论哪方对错，我个人倾向于认为大学录取应该绝对平等，而助学项目应该重点向比如SAT考试免费，SAT补习班免费，高中教育资源流动项目等等，而大学作为研究导向的教育机构应该减少主观，非综合能力为本的录取标准。重点是，一次又一次地，我们认识到平等这个词没法在人群里达成共识，美国的平等在发展中国家看来就是奢侈，而西欧有些国家的平等和福利政策，又会让部分美国人觉得是共产主义而去厌恶，实在是讽刺。

]]>从宿舍里搬出来这三个月里，家里的包装盒及说明书堆积和被丢弃的速度都非常快。其中最多的肯定是开学第二周的时候伴随宜家家居送达的那一批。装家具大家都懂的，一般总是要读说明书的。宜家的说明书大体上其实画的不错，无论是细节还是在易错零件的装配步骤上对比强调，还是蛮用心的。但最用心的，还是他们不厌其烦地在所有包装袋子和零件上都印上不要吞食和小心窒息 - 自然，主要是针对儿童的。

我其实可以算是个“喜欢读说明书”的人：即便性别认知在长大的过程中有点非传统化，但我从小到大主要扯着大人给买的东西基本还是电子产品。打开包装看到完好的说明书一方面给当时的我带来了剁手的快感（用家长的钱剁手其实更开心），另一方面电子产品的操作指南和指示说明什么的也极大地满足了年幼的我的好奇心。从四驱车到MP3，电子产品因为有零件和包装，总免不了在说明书第一页写一堆警告，更不提经常以单独的一册出现的有毒害物质检测了。我一开始超喜欢读这些说明书的，比如我记得很清楚有一款充电电池有提到电池含有有毒重金属，但是仅在内部，所以不泄露的情况下是安全的。

读久了肯定会厌的，主要是当年电子产品还没有爆炸发展，所有操作界面翻来覆去也就几种交互模式，很容易给人摸清套路，特别是幼年时期记忆力还没有衰退的我。总之后来我又觉得药物的说明书很有趣，画分子式的西药说明书很帅不说，那些讲副作用和摄入方式的部分也让人可以脑补出很多背后的原理什么的，总之也是很好的消遣。再之后我就不怎么好好读说明书了，基本上看一眼怎么开机或者什么时间吃药就差不多了，除非是第一次用的东西（比如第一次买相机），但大体上心态是比较功利而不是寻乐地去找对自己有用的信息。

然而来了美国之后事情有了新变化。一方面是很多东西的操作方法完全不一样，另外一方面是这里的说明书写作模式也不熟悉 - 这反而给了人新鲜感。要我说的话，学习美国人怎么最正经地说话去看 C-Span，学习怎么最正经的写作去看 Legal Document，说明书也算其中之一。总而言之，时间回到上周，在读了不少说明书之后，我收到了在 Dyson 买的无线吸尘器，我照例先感受了一下，然后掏出说明书。

然而我发现我看说明书的速度变慢了。我以前确实没用过吸尘器，所以按理说也正常，但我仗着 Dyson 的吸尘器好歹是个假装高科技的电子产品，应该随便看看就行了：然而事实上我花了一会儿才看懂怎么在线缠住的情况下打开转接头。

不知为何我对这件事情有些感触，一方面觉得自己可能确实是智障，但同时也觉得可能以前把说明书主要当做废话的看法确实不太对。当代的说明书、手册一类的东西明面上主要有两个作用，一为实用角度、另一为法律角度。实用角度很好理解，食品在微波炉里什么功率加热几秒就属于这一类；法律角度也比较容易联想，老奶奶被麦当劳热咖啡烫伤后打天价官司的故事大家都听说过，简而言之就是为了确保不要有意外的用户以意外的方式使用了自己的产品结果导致公司自己意外地需要赔钱。但除此二者之外，说明手册最不易被察觉的效果可能是向阅读者介绍这个世界的 norm。

我们生活在当代的人用当代的产品，自然不会读个说明书读出世界观被刷新的感觉，最多只会觉得自己真的要自己的父辈一样用个手机都要研究说明书了。但仔细想想，难道50年前没有说明书么？说明书从来没有很简单读，因为一本说明书不仅代表了一个特定的产品型号如何使用，更代表了地球上这类产品都能以什么样的性能达到什么效果，这是很薄但内容也很丰富的某个时代的切片。

想象一下某位80年代的熟练会计，上班某二天，有人穿越时空给ta带来了 Windows 10 电脑，打印机，Word 和 Excel，让出一份财务报表，就算 F1 的帮助菜单多么屌，这种工作范式上的大变化也是难以克服的。不那么极端的例子而言，在 iPhone 之前，双指缩放这种操作是不存在的。如果我们说从一指到多指还是可以想象的，但如果我们把搭载 iOS 11 的手机给一个只用过寻呼机的30岁上班族呢？这时候 iOS 所谓的直观和用户友好在时代跨度前荡然无存。但这之间也就隔了15年多而已（对中国人而言）。

说明书之所以会让人觉得废话多，多半是我们已经在它试图说明的领域里积累了生活经验。但时不时，特别是我们接触到新的东西的时候，我们甚至会想要一本废话连篇的说明书，以免我们甚至看不懂其中最基本的操作 - 我在看编程方面的手册的时候经常有这种想法，希望作者多写点废话告诉我他每一步在做什么。

]]>tl;dr ver. : Device Manager -> Display Adapter -> Intel Graphics -> Uninstall Driver (DO NOT detele from system) -> restart

Noticed display keep changing contrast (not brightness cause I knew I disabled it) ratio while watching YouTube videos. Specifically, wether or not the progress bar show seems to be causing the system to change the contrast of the whole display.

Same thing happens in PhotoShop when differrent sub-window is at the front.

Then reboot. Problem gone.

]]>Trump就职之后半年过去了，推进很多政策困难重重，最近总算在DACA/DAPA事情上有了些进展，墨西哥边境造墙的工程也进入了早期的小型模拟建设来验证招标的阶段；不过唐总一百多天里光高尔夫就打了40多天难免被媒体批判一通。

说到媒体，2016选举年暴露出了媒体很多问题----有他们自己技术方面的问题，比如报导的bias，比如调研的时候忽略了一些群体；但还有一方面是媒体主观上的变质：新时代的媒体在资本和成本/收入的逼迫下不断把报道标签化，肤浅化，很多有深度或者前因后果复杂的问题，被媒体带上个标签（最常见的是各种PC问题）然后几句话就激起民愤，而且在游行等事件上也缺乏报道实际情况的资料，经常是主持人嘉宾坐在演播室里大谈政治理念等等，可以说是目前灯塔国空前舆论矛盾的一大助因。

最近灯塔国公众舆论风起云涌，antifa带上之前一波BLM的群众基础继续搞事，其中Boston的反游行可以说是最能体现此群体思想倾向和行动原则的事件。

发达国家常被人吹捧的其中一个方面就是所谓的【普及高等教育】：无论是灯塔国这样的教育补贴(Student Aid)大国，还是北欧诸国这样高福利高普及高等教育和成人大学的国家，似乎发达国家的教育率必然就高出很多，以至于有时候我们会误以为是高教育水平造就了国家的发达。

然而相关性不代表因果性。虽然不可否认，大多数人心目中的理想社会，必然是有教育普及这一因素的，但这不代表没有普遍高等教育就不能成就发达国家（比如我们可以设想一个没那么腐败的沙特）；同时也更不意味着，只要有相对高的教育，就能维持一个国家的相对发达。

但就算抛开以上的潜在问题，目前普遍存在的教育模式却有着更本质的问题，那就是普及了教育（作为一种训练)，却并没有达到普及思维水平的效果。这一现象其实是人类群里活动的本质造成的 —— 冷静而反主流的领导者永远是少数，而固化激情盲从的永远是多数 —— 两百年前种族/性别歧视横行，去歧视，找政治正确是一种少数人的先锋运动。然而当代西方的教育界，却把结果作为过程去教授给学生，就是一种本末倒置 —— 学生知道要有批判思维，却为了批判而去批判，为了政治正确而批斗一切，为了体现自己有判断力而去矫枉过正抹黑自己种族 —— 200 年前的先锋很容易沦落为 200 年后依样画瓢般愚蠢的观点。

其实这有点像科学教育，科学的目标永远是关于拓展人类对于自然认识的最前沿 —— 正因为是拓展，所以没人知道结果是什么，所以也没法用结果去教育学生 —— 把十几年前的 “最新" 方法拿出来生搬硬套，显然是愚蠢的，而且在结果为王的实验科学界是行不通的。

但这套方法却在公众舆论和政治场里行得通，因为大众所花费的精力，远远不足以真的在现代社会的背景下想清楚这么多问题，但人群又是容易被操纵和煽动的 —— 被政治家，被媒体，甚至被网络谣言。因为社会问题没有 “实验结果”，嗓门和拳头就能决定利益分配，所以精英甚至乐于刻意让大众对一些社会问题陷入逻辑错误甚至激烈冲突的状况之中。

应试教育也加剧了这种教育 ≠ 教育的困境之中，原本考试的意思是让学生在练习中加强水平，但为了提高考试的结果，以“过拟合”的方式和态度去对待一门学科反而是对考试结果的最优解，这与懒得思考而只追求简单口号的很多游行抗议，很多可笑的追求政治正确，本质上是一回事 —— 只有口号够简单无脑，而不要细节才能引起群众的注意，因为群众没那么多精力仔细思考某一问题。

这也许是人类社会性本能自发产生的困境，教育和经济水平高了自然会想在社会问题中有一席之地，但无奈精英永远是少数人，而多数人并没有足够好的思维能力去多面地考虑一个问题，劣币驱逐良币的结果是既然无脑更吃香，为什么还要去真的以理服人呢？

一开始我们为什么觉得花纳税人的钱去提高教育水平是好事来着？

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