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	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167965</id>
		<title>2034: Equations</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167965"/>
				<updated>2019-01-11T01:08:18Z</updated>
		
		<summary type="html">&lt;p&gt;RandomBananazz: more minor math updates&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 2034&lt;br /&gt;
| date      = August 17, 2018&lt;br /&gt;
| title     = Equations&lt;br /&gt;
| image     = equations.png&lt;br /&gt;
| titletext = All electromagnetic equations: The same as all fluid dynamics equations, but with the 8 and 23 replaced with the permittivity and permeability of free space, respectively.&lt;br /&gt;
}}&lt;br /&gt;
==Explanation==&lt;br /&gt;
&lt;br /&gt;
This comic gives a set of mock equations. To anyone not familiar with the field in question they look pretty similar to what you might find in research papers or on the relevant Wikipedia pages. Most of the jokes are related to the symbols or &amp;quot;look&amp;quot; of most equations in the given field.&lt;br /&gt;
&lt;br /&gt;
The comic makes jokes about the fields of kinematics, number theory, fluid dynamics, quantum mechanics, chemistry, quantum gravity, gauge theory, cosmology, and physics equations. Of course, all of the equations listed are not real equations (&amp;lt;math&amp;gt;\pi-\infty&amp;lt;/math&amp;gt; and H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT are clearly jokes and making a mockery of the given field). As always, Randall is just having a laugh.&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;E=K_{0}t+\frac{1}{2}\rho{}vt^2&amp;lt;/math&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;K_{n}=\sum_{i=0}^{\infty}\sum_{\pi=0}^{\infty}(n-\pi)(i+e^{\pi-\infty})&amp;lt;/math&amp;gt;&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;\frac{\partial}{\partial{t}}\nabla\cdot\rho=\frac{8}{23}\oint\!\!\!\!\oint\rho\,{ds}\,{dt}\cdot{}\rho\frac{\partial}{\partial\nabla}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;|\psi_{x,y}\rangle=A(\psi)A(|x\rangle\otimes|y\rangle)&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;CH_4+OH+HEAT\rightarrow{}H_2O+CH_{2}+H_2EAT&amp;lt;/math&amp;gt;&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;SU(2)U(1)\times{}SU(U(2))&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;H(t)+\Omega+G\cdot\nabla...\begin{cases}...&amp;gt;0\textrm{\ (Hubble\ model)}\\&lt;br /&gt;
...=0\textrm{\ (Flat\ sphere\ model)}\\&lt;br /&gt;
...&amp;lt;0\textrm{\ (Bright\ dark\ matter\ model)}&lt;br /&gt;
\end{cases}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
* Most '''kinematics''' equations tend to make heavy use of constants, addition, powers, and multiplication. This specific equation resembles the actual kinematics equation d = vt + 1/2at^2, but replaces a (acceleration) with v (velocity) and replaces velocity with &amp;quot;K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;&amp;quot;, which is not a term used in kinematics.&lt;br /&gt;
&lt;br /&gt;
* Randall jokes about how '''number theory''' often involves the use of summations. The use of ''&amp;amp;pi;'' as an integer variable in the double summation is a joke, as ''&amp;amp;pi;'' is essentially always used for the well-known constant 3.14159..., not a variable. The use of ''i'' as a summation variable '''is''' common, though it can also be confused with the imaginary unit &amp;amp;radic;-1. The constants ''e'', ''i'', and ''&amp;amp;pi;'', as well as the theoretical upper bound &amp;lt;math&amp;gt;\infty&amp;lt;/math&amp;gt;, often appear in number theory equations.&lt;br /&gt;
&lt;br /&gt;
* '''Fluid dynamics equations''' often involve copious integrals, especially those over closed contours as done here, which are often the main telling factors of those equations to an outsider.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum mechanics''' often involves some of the foreign-looking symbols listed, including {{w|Bra–ket notation|bra-ket notation}}, the {{w|Tensor product|tensor product}}, and the Greek letter Psi for a quantum state.&lt;br /&gt;
&lt;br /&gt;
* '''Chemistry equations''' use chemical formulas, as shown. The addition of H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT and HEAT is just a joke. Randall gets the {{w|stoichiometry}} of this equation correct, with the same number of all types of 'atoms' on each side of the equation.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum gravity''' uses mathematical {{w|Group (mathematics)|groups}} denoted by uppercase letters, as shown. {{w|Special unitary group|SU(2)}}, {{w|Unitary group|U(1)}}, and {{w|Unitary group|U(2)}} are all well-studied groups, though 'SU(U(2))' makes no sense.  The lack of relator means this expression isn't an equation.  Here is a possible pun, on &amp;quot;Sue you too... you won&amp;quot;... &amp;quot;Sue you, you too&amp;quot;, though it's unclear how it fits in here.&lt;br /&gt;
&lt;br /&gt;
* '''Gauge theory''' is a subset of field theory. Most gauge theory equations appear to have many strange-looking constants and variables with odd labels.&lt;br /&gt;
&lt;br /&gt;
* '''Cosmology''' is the science of the development and ultimate fate of the universe. The joke here may be pertaining to the different models accepted in the field of cosmology. H is the {{w|Hubble's law#Time-dependence of Hubble parameter|Hubble parameter}}, &amp;amp;Omega; is the universal {{w|Friedmann equations#Density parameter|density parameter}}, G is the {{w|gravitational constant}}, and &amp;amp;Lambda; is the {{w|cosmological constant}}.&lt;br /&gt;
&lt;br /&gt;
* The joke about the &amp;quot;truly deep physics equations&amp;quot; is that most of the universal physics equations are simple, almost exceedingly so. One example is Einstein's &amp;lt;math&amp;gt;E = mc^2&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
* The title text is referencing the fact that the electric and magnetic fields are often explained to physics students using an analogy with fluid dynamics, as well as the fact that they do share some similarities (only in terms of mathematical description as three-dimensional vector fields) with fluids. The permittivity constant (represented with ''&amp;amp;epsilon;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) and the permeability constant (represented with ''&amp;amp;mu;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) are coefficients that relate the amount of charge required to cause a specific amount of electric flux in a vacuum and the ability of vacuum to support the formation of magnetic fields, respectively. They appear frequently in Maxwell's equations (the equations that define the electric and magnetic fields in classical mechanics), so Randall is making the joke that any surface integral with them in it automatically is an electromagnetism equation.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Nine equations are listed, three in the top row and two in each of the next three rows. Below each equation there are labels:]&lt;br /&gt;
&lt;br /&gt;
:E=K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;t+1/2 &amp;amp;rho;vt&amp;lt;sup&amp;gt;2&amp;lt;/sup&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:K&amp;lt;sub&amp;gt;n&amp;lt;/sub&amp;gt;=&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;i=0&amp;lt;/sub&amp;gt;&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;&amp;amp;pi;=0&amp;lt;/sub&amp;gt;(n-&amp;amp;pi;)(i-e&amp;lt;sup&amp;gt;&amp;amp;pi;-&amp;amp;infin;&amp;lt;/sup&amp;gt;) [K sub n = the summation from i = 0 to infinity of the sum from pi = 0 to infinity of (n - pi) * (i-e^(pi-infinity))]&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x2202;/&amp;amp;#x2202;t &amp;amp;nabla;&amp;amp;sdot;&amp;amp;rho;=8/23 (&amp;amp;#x222F; &amp;amp;rho; ds dt &amp;amp;sdot; &amp;amp;rho; &amp;amp;#x2202;/&amp;amp;#x2202;&amp;amp;nabla;)&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:|&amp;amp;psi;&amp;lt;sub&amp;gt;x,y&amp;lt;/sub&amp;gt;&amp;amp;#x232a;=A(&amp;amp;psi;)A(|x&amp;amp;#x232a;&amp;amp;#x2297;|y&amp;amp;#x232a;)&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;+OH+HEAT&amp;amp;rarr;H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O+CH&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;+H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:SU(2)U(1)&amp;amp;times;SU(U(2))&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:H(t)+&amp;amp;Omega;+G&amp;amp;sdot;&amp;amp;Lambda; ... &lt;br /&gt;
:[There is a brace linking the three cases together.]&lt;br /&gt;
:... &amp;gt; 0 (Hubble model)&lt;br /&gt;
:... = 0 (Flat sphere model)&lt;br /&gt;
:... &amp;lt; 0 (Bright dark matter model)&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Science]]&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Math]]&lt;br /&gt;
[[Category:Chemistry]]&lt;br /&gt;
[[Category:Astronomy]]&lt;/div&gt;</summary>
		<author><name>RandomBananazz</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167964</id>
		<title>2034: Equations</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167964"/>
				<updated>2019-01-11T01:06:15Z</updated>
		
		<summary type="html">&lt;p&gt;RandomBananazz: again fixed some math markup errors&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 2034&lt;br /&gt;
| date      = August 17, 2018&lt;br /&gt;
| title     = Equations&lt;br /&gt;
| image     = equations.png&lt;br /&gt;
| titletext = All electromagnetic equations: The same as all fluid dynamics equations, but with the 8 and 23 replaced with the permittivity and permeability of free space, respectively.&lt;br /&gt;
}}&lt;br /&gt;
==Explanation==&lt;br /&gt;
&lt;br /&gt;
This comic gives a set of mock equations. To anyone not familiar with the field in question they look pretty similar to what you might find in research papers or on the relevant Wikipedia pages. Most of the jokes are related to the symbols or &amp;quot;look&amp;quot; of most equations in the given field.&lt;br /&gt;
&lt;br /&gt;
The comic makes jokes about the fields of kinematics, number theory, fluid dynamics, quantum mechanics, chemistry, quantum gravity, gauge theory, cosmology, and physics equations. Of course, all of the equations listed are not real equations (&amp;lt;math&amp;gt;\pi-\infty&amp;lt;/math&amp;gt; and H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT are clearly jokes and making a mockery of the given field). As always, Randall is just having a laugh.&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;E=K_{0}t+\frac{1}{2}\rho{}vt^2&amp;lt;/math&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;K_{n}=\sum_{i=0}^{\infty}\sum_{\pi=0}^{\infty}(n-\pi)(i+e^{\pi-\infty})&amp;lt;/math&amp;gt;&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;\frac{\partial}{\partial{t}}\nabla\cdot\rho=\frac{8}{23}\oint\!\!\!\!\oint\rho\,{ds}\,{dt}\cdot{}\rho\frac{\partial}{\partial\nabla}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;|\psi_{x,y}\rangle=A(\psi)A(|x\rangle\otimes|y\rangle)&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;CH_4+OH+HEAT\rightarrow{}H_2O+CH_{2}+H_2EAT&amp;lt;/math&amp;gt;&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;SU(2)U(1)\times{}SU(U(2))&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;H(t)+\omega+G\cdot\nabla...\begin{cases}...&amp;gt;0\textrm{\ (Hubble\ model)}\\&lt;br /&gt;
...=0\textrm{\ (Flat\ sphere\ model)}\\&lt;br /&gt;
...&amp;lt;0\textrm{\ (Bright\ dark\ matter\ model)}&lt;br /&gt;
\end{cases}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
* Most '''kinematics''' equations tend to make heavy use of constants, addition, powers, and multiplication. This specific equation resembles the actual kinematics equation d = vt + 1/2at^2, but replaces a (acceleration) with v (velocity) and replaces velocity with &amp;quot;K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;&amp;quot;, which is not a term used in kinematics.&lt;br /&gt;
&lt;br /&gt;
* Randall jokes about how '''number theory''' often involves the use of summations. The use of ''&amp;amp;pi;'' as an integer variable in the double summation is a joke, as ''&amp;amp;pi;'' is essentially always used for the well-known constant 3.14159..., not a variable. The use of ''i'' as a summation variable '''is''' common, though it can also be confused with the imaginary unit &amp;amp;radic;-1. The constants ''e'', ''i'', and ''&amp;amp;pi;'', as well as the theoretical upper bound &amp;lt;math&amp;gt;\infty&amp;lt;/math&amp;gt;, often appear in number theory equations.&lt;br /&gt;
&lt;br /&gt;
* '''Fluid dynamics equations''' often involve copious integrals, especially those over closed contours as done here, which are often the main telling factors of those equations to an outsider.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum mechanics''' often involves some of the foreign-looking symbols listed, including {{w|Bra–ket notation|bra-ket notation}}, the {{w|Tensor product|tensor product}}, and the Greek letter Psi for a quantum state.&lt;br /&gt;
&lt;br /&gt;
* '''Chemistry equations''' use chemical formulas, as shown. The addition of H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT and HEAT is just a joke. Randall gets the {{w|stoichiometry}} of this equation correct, with the same number of all types of 'atoms' on each side of the equation.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum gravity''' uses mathematical {{w|Group (mathematics)|groups}} denoted by uppercase letters, as shown. {{w|Special unitary group|SU(2)}}, {{w|Unitary group|U(1)}}, and {{w|Unitary group|U(2)}} are all well-studied groups, though 'SU(U(2))' makes no sense.  The lack of relator means this expression isn't an equation.  Here is a possible pun, on &amp;quot;Sue you too... you won&amp;quot;... &amp;quot;Sue you, you too&amp;quot;, though it's unclear how it fits in here.&lt;br /&gt;
&lt;br /&gt;
* '''Gauge theory''' is a subset of field theory. Most gauge theory equations appear to have many strange-looking constants and variables with odd labels.&lt;br /&gt;
&lt;br /&gt;
* '''Cosmology''' is the science of the development and ultimate fate of the universe. The joke here may be pertaining to the different models accepted in the field of cosmology. H is the {{w|Hubble's law#Time-dependence of Hubble parameter|Hubble parameter}}, &amp;amp;Omega; is the universal {{w|Friedmann equations#Density parameter|density parameter}}, G is the {{w|gravitational constant}}, and &amp;amp;Lambda; is the {{w|cosmological constant}}.&lt;br /&gt;
&lt;br /&gt;
* The joke about the &amp;quot;truly deep physics equations&amp;quot; is that most of the universal physics equations are simple, almost exceedingly so. One example is Einstein's &amp;lt;math&amp;gt;E = mc^2&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
* The title text is referencing the fact that the electric and magnetic fields are often explained to physics students using an analogy with fluid dynamics, as well as the fact that they do share some similarities (only in terms of mathematical description as three-dimensional vector fields) with fluids. The permittivity constant (represented with ''&amp;amp;epsilon;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) and the permeability constant (represented with ''&amp;amp;mu;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) are coefficients that relate the amount of charge required to cause a specific amount of electric flux in a vacuum and the ability of vacuum to support the formation of magnetic fields, respectively. They appear frequently in Maxwell's equations (the equations that define the electric and magnetic fields in classical mechanics), so Randall is making the joke that any surface integral with them in it automatically is an electromagnetism equation.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Nine equations are listed, three in the top row and two in each of the next three rows. Below each equation there are labels:]&lt;br /&gt;
&lt;br /&gt;
:E=K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;t+1/2 &amp;amp;rho;vt&amp;lt;sup&amp;gt;2&amp;lt;/sup&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:K&amp;lt;sub&amp;gt;n&amp;lt;/sub&amp;gt;=&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;i=0&amp;lt;/sub&amp;gt;&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;&amp;amp;pi;=0&amp;lt;/sub&amp;gt;(n-&amp;amp;pi;)(i-e&amp;lt;sup&amp;gt;&amp;amp;pi;-&amp;amp;infin;&amp;lt;/sup&amp;gt;) [K sub n = the summation from i = 0 to infinity of the sum from pi = 0 to infinity of (n - pi) * (i-e^(pi-infinity))]&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x2202;/&amp;amp;#x2202;t &amp;amp;nabla;&amp;amp;sdot;&amp;amp;rho;=8/23 (&amp;amp;#x222F; &amp;amp;rho; ds dt &amp;amp;sdot; &amp;amp;rho; &amp;amp;#x2202;/&amp;amp;#x2202;&amp;amp;nabla;)&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:|&amp;amp;psi;&amp;lt;sub&amp;gt;x,y&amp;lt;/sub&amp;gt;&amp;amp;#x232a;=A(&amp;amp;psi;)A(|x&amp;amp;#x232a;&amp;amp;#x2297;|y&amp;amp;#x232a;)&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;+OH+HEAT&amp;amp;rarr;H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O+CH&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;+H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:SU(2)U(1)&amp;amp;times;SU(U(2))&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:H(t)+&amp;amp;Omega;+G&amp;amp;sdot;&amp;amp;Lambda; ... &lt;br /&gt;
:[There is a brace linking the three cases together.]&lt;br /&gt;
:... &amp;gt; 0 (Hubble model)&lt;br /&gt;
:... = 0 (Flat sphere model)&lt;br /&gt;
:... &amp;lt; 0 (Bright dark matter model)&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Science]]&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Math]]&lt;br /&gt;
[[Category:Chemistry]]&lt;br /&gt;
[[Category:Astronomy]]&lt;/div&gt;</summary>
		<author><name>RandomBananazz</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167963</id>
		<title>2034: Equations</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167963"/>
				<updated>2019-01-11T01:05:31Z</updated>
		
		<summary type="html">&lt;p&gt;RandomBananazz: fixed an error in the fluid dynamics equations math markup&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 2034&lt;br /&gt;
| date      = August 17, 2018&lt;br /&gt;
| title     = Equations&lt;br /&gt;
| image     = equations.png&lt;br /&gt;
| titletext = All electromagnetic equations: The same as all fluid dynamics equations, but with the 8 and 23 replaced with the permittivity and permeability of free space, respectively.&lt;br /&gt;
}}&lt;br /&gt;
==Explanation==&lt;br /&gt;
&lt;br /&gt;
This comic gives a set of mock equations. To anyone not familiar with the field in question they look pretty similar to what you might find in research papers or on the relevant Wikipedia pages. Most of the jokes are related to the symbols or &amp;quot;look&amp;quot; of most equations in the given field.&lt;br /&gt;
&lt;br /&gt;
The comic makes jokes about the fields of kinematics, number theory, fluid dynamics, quantum mechanics, chemistry, quantum gravity, gauge theory, cosmology, and physics equations. Of course, all of the equations listed are not real equations (&amp;lt;math&amp;gt;\pi-\infty&amp;lt;/math&amp;gt; and H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT are clearly jokes and making a mockery of the given field). As always, Randall is just having a laugh.&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;E=K_{0}t+\frac{1}{2}\rho{}vt^2&amp;lt;/math&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;K_{n}=\sum_{i=0}^{\infty}\sum_{\pi=0}^{\infty}(n-\pi)(i+e^{\pi-\infty})&amp;lt;/math&amp;gt;&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;\frac{\partial}{\partial{t}}\nabla\cdot\rho=\frac{8}{23}\oint\!\!\!\!\oint\rho\,{ds}\,{dt}\cdot{}\rho\frac{\psi}{\psi\nabla}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;|\psi_{x,y}\rangle=A(\psi)A(|x\rangle\otimes|y\rangle)&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;CH_4+OH+HEAT\rightarrow{}H_2O+CH_{2}+H_2EAT&amp;lt;/math&amp;gt;&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;SU(2)U(1)\times{}SU(U(2))&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;H(t)+\omega+G\cdot\nabla...\begin{cases}...&amp;gt;0\textrm{\ (Hubble\ model)}\\&lt;br /&gt;
...=0\textrm{\ (Flat\ sphere\ model)}\\&lt;br /&gt;
...&amp;lt;0\textrm{\ (Bright\ dark\ matter\ model)}&lt;br /&gt;
\end{cases}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
* Most '''kinematics''' equations tend to make heavy use of constants, addition, powers, and multiplication. This specific equation resembles the actual kinematics equation d = vt + 1/2at^2, but replaces a (acceleration) with v (velocity) and replaces velocity with &amp;quot;K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;&amp;quot;, which is not a term used in kinematics.&lt;br /&gt;
&lt;br /&gt;
* Randall jokes about how '''number theory''' often involves the use of summations. The use of ''&amp;amp;pi;'' as an integer variable in the double summation is a joke, as ''&amp;amp;pi;'' is essentially always used for the well-known constant 3.14159..., not a variable. The use of ''i'' as a summation variable '''is''' common, though it can also be confused with the imaginary unit &amp;amp;radic;-1. The constants ''e'', ''i'', and ''&amp;amp;pi;'', as well as the theoretical upper bound &amp;lt;math&amp;gt;\infty&amp;lt;/math&amp;gt;, often appear in number theory equations.&lt;br /&gt;
&lt;br /&gt;
* '''Fluid dynamics equations''' often involve copious integrals, especially those over closed contours as done here, which are often the main telling factors of those equations to an outsider.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum mechanics''' often involves some of the foreign-looking symbols listed, including {{w|Bra–ket notation|bra-ket notation}}, the {{w|Tensor product|tensor product}}, and the Greek letter Psi for a quantum state.&lt;br /&gt;
&lt;br /&gt;
* '''Chemistry equations''' use chemical formulas, as shown. The addition of H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT and HEAT is just a joke. Randall gets the {{w|stoichiometry}} of this equation correct, with the same number of all types of 'atoms' on each side of the equation.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum gravity''' uses mathematical {{w|Group (mathematics)|groups}} denoted by uppercase letters, as shown. {{w|Special unitary group|SU(2)}}, {{w|Unitary group|U(1)}}, and {{w|Unitary group|U(2)}} are all well-studied groups, though 'SU(U(2))' makes no sense.  The lack of relator means this expression isn't an equation.  Here is a possible pun, on &amp;quot;Sue you too... you won&amp;quot;... &amp;quot;Sue you, you too&amp;quot;, though it's unclear how it fits in here.&lt;br /&gt;
&lt;br /&gt;
* '''Gauge theory''' is a subset of field theory. Most gauge theory equations appear to have many strange-looking constants and variables with odd labels.&lt;br /&gt;
&lt;br /&gt;
* '''Cosmology''' is the science of the development and ultimate fate of the universe. The joke here may be pertaining to the different models accepted in the field of cosmology. H is the {{w|Hubble's law#Time-dependence of Hubble parameter|Hubble parameter}}, &amp;amp;Omega; is the universal {{w|Friedmann equations#Density parameter|density parameter}}, G is the {{w|gravitational constant}}, and &amp;amp;Lambda; is the {{w|cosmological constant}}.&lt;br /&gt;
&lt;br /&gt;
* The joke about the &amp;quot;truly deep physics equations&amp;quot; is that most of the universal physics equations are simple, almost exceedingly so. One example is Einstein's &amp;lt;math&amp;gt;E = mc^2&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
* The title text is referencing the fact that the electric and magnetic fields are often explained to physics students using an analogy with fluid dynamics, as well as the fact that they do share some similarities (only in terms of mathematical description as three-dimensional vector fields) with fluids. The permittivity constant (represented with ''&amp;amp;epsilon;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) and the permeability constant (represented with ''&amp;amp;mu;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) are coefficients that relate the amount of charge required to cause a specific amount of electric flux in a vacuum and the ability of vacuum to support the formation of magnetic fields, respectively. They appear frequently in Maxwell's equations (the equations that define the electric and magnetic fields in classical mechanics), so Randall is making the joke that any surface integral with them in it automatically is an electromagnetism equation.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Nine equations are listed, three in the top row and two in each of the next three rows. Below each equation there are labels:]&lt;br /&gt;
&lt;br /&gt;
:E=K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;t+1/2 &amp;amp;rho;vt&amp;lt;sup&amp;gt;2&amp;lt;/sup&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:K&amp;lt;sub&amp;gt;n&amp;lt;/sub&amp;gt;=&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;i=0&amp;lt;/sub&amp;gt;&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;&amp;amp;pi;=0&amp;lt;/sub&amp;gt;(n-&amp;amp;pi;)(i-e&amp;lt;sup&amp;gt;&amp;amp;pi;-&amp;amp;infin;&amp;lt;/sup&amp;gt;) [K sub n = the summation from i = 0 to infinity of the sum from pi = 0 to infinity of (n - pi) * (i-e^(pi-infinity))]&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x2202;/&amp;amp;#x2202;t &amp;amp;nabla;&amp;amp;sdot;&amp;amp;rho;=8/23 (&amp;amp;#x222F; &amp;amp;rho; ds dt &amp;amp;sdot; &amp;amp;rho; &amp;amp;#x2202;/&amp;amp;#x2202;&amp;amp;nabla;)&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:|&amp;amp;psi;&amp;lt;sub&amp;gt;x,y&amp;lt;/sub&amp;gt;&amp;amp;#x232a;=A(&amp;amp;psi;)A(|x&amp;amp;#x232a;&amp;amp;#x2297;|y&amp;amp;#x232a;)&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;+OH+HEAT&amp;amp;rarr;H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O+CH&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;+H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:SU(2)U(1)&amp;amp;times;SU(U(2))&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:H(t)+&amp;amp;Omega;+G&amp;amp;sdot;&amp;amp;Lambda; ... &lt;br /&gt;
:[There is a brace linking the three cases together.]&lt;br /&gt;
:... &amp;gt; 0 (Hubble model)&lt;br /&gt;
:... = 0 (Flat sphere model)&lt;br /&gt;
:... &amp;lt; 0 (Bright dark matter model)&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Science]]&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Math]]&lt;br /&gt;
[[Category:Chemistry]]&lt;br /&gt;
[[Category:Astronomy]]&lt;/div&gt;</summary>
		<author><name>RandomBananazz</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167962</id>
		<title>2034: Equations</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=2034:_Equations&amp;diff=167962"/>
				<updated>2019-01-11T00:56:11Z</updated>
		
		<summary type="html">&lt;p&gt;RandomBananazz: Converted some of the math equations to the math markup. There are some really weird diacritics and symbols in the gauge theory and deep physics equations that couldn't be put into the markup language. If it looks bad, feel free to revert.&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 2034&lt;br /&gt;
| date      = August 17, 2018&lt;br /&gt;
| title     = Equations&lt;br /&gt;
| image     = equations.png&lt;br /&gt;
| titletext = All electromagnetic equations: The same as all fluid dynamics equations, but with the 8 and 23 replaced with the permittivity and permeability of free space, respectively.&lt;br /&gt;
}}&lt;br /&gt;
==Explanation==&lt;br /&gt;
&lt;br /&gt;
This comic gives a set of mock equations. To anyone not familiar with the field in question they look pretty similar to what you might find in research papers or on the relevant Wikipedia pages. Most of the jokes are related to the symbols or &amp;quot;look&amp;quot; of most equations in the given field.&lt;br /&gt;
&lt;br /&gt;
The comic makes jokes about the fields of kinematics, number theory, fluid dynamics, quantum mechanics, chemistry, quantum gravity, gauge theory, cosmology, and physics equations. Of course, all of the equations listed are not real equations (&amp;lt;math&amp;gt;\pi-\infty&amp;lt;/math&amp;gt; and H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT are clearly jokes and making a mockery of the given field). As always, Randall is just having a laugh.&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;E=K_{0}t+\frac{1}{2}\rho{}vt^2&amp;lt;/math&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;K_{n}=\sum_{i=0}^{\infty}\sum_{\pi=0}^{\infty}(n-\pi)(i+e^{\pi-\infty})&amp;lt;/math&amp;gt;&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;\frac{\psi}{\psi{t}}\nabla\cdot\rho=\frac{8}{23}\oint\!\!\!\!\oint\rho\,{ds}\,{dt}\cdot{}\rho\frac{\psi}{\psi\nabla}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;|\psi_{x,y}\rangle=A(\psi)A(|x\rangle\otimes|y\rangle)&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;CH_4+OH+HEAT\rightarrow{}H_2O+CH_{2}+H_2EAT&amp;lt;/math&amp;gt;&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;SU(2)U(1)\times{}SU(U(2))&amp;lt;/math&amp;gt;&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt;H(t)+\omega+G\cdot\nabla...\begin{cases}...&amp;gt;0\textrm{\ (Hubble\ model)}\\&lt;br /&gt;
...=0\textrm{\ (Flat\ sphere\ model)}\\&lt;br /&gt;
...&amp;lt;0\textrm{\ (Bright\ dark\ matter\ model)}&lt;br /&gt;
\end{cases}&amp;lt;/math&amp;gt;&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
* Most '''kinematics''' equations tend to make heavy use of constants, addition, powers, and multiplication. This specific equation resembles the actual kinematics equation d = vt + 1/2at^2, but replaces a (acceleration) with v (velocity) and replaces velocity with &amp;quot;K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;&amp;quot;, which is not a term used in kinematics.&lt;br /&gt;
&lt;br /&gt;
* Randall jokes about how '''number theory''' often involves the use of summations. The use of ''&amp;amp;pi;'' as an integer variable in the double summation is a joke, as ''&amp;amp;pi;'' is essentially always used for the well-known constant 3.14159..., not a variable. The use of ''i'' as a summation variable '''is''' common, though it can also be confused with the imaginary unit &amp;amp;radic;-1. The constants ''e'', ''i'', and ''&amp;amp;pi;'', as well as the theoretical upper bound &amp;lt;math&amp;gt;\infty&amp;lt;/math&amp;gt;, often appear in number theory equations.&lt;br /&gt;
&lt;br /&gt;
* '''Fluid dynamics equations''' often involve copious integrals, especially those over closed contours as done here, which are often the main telling factors of those equations to an outsider.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum mechanics''' often involves some of the foreign-looking symbols listed, including {{w|Bra–ket notation|bra-ket notation}}, the {{w|Tensor product|tensor product}}, and the Greek letter Psi for a quantum state.&lt;br /&gt;
&lt;br /&gt;
* '''Chemistry equations''' use chemical formulas, as shown. The addition of H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT and HEAT is just a joke. Randall gets the {{w|stoichiometry}} of this equation correct, with the same number of all types of 'atoms' on each side of the equation.&lt;br /&gt;
&lt;br /&gt;
* '''Quantum gravity''' uses mathematical {{w|Group (mathematics)|groups}} denoted by uppercase letters, as shown. {{w|Special unitary group|SU(2)}}, {{w|Unitary group|U(1)}}, and {{w|Unitary group|U(2)}} are all well-studied groups, though 'SU(U(2))' makes no sense.  The lack of relator means this expression isn't an equation.  Here is a possible pun, on &amp;quot;Sue you too... you won&amp;quot;... &amp;quot;Sue you, you too&amp;quot;, though it's unclear how it fits in here.&lt;br /&gt;
&lt;br /&gt;
* '''Gauge theory''' is a subset of field theory. Most gauge theory equations appear to have many strange-looking constants and variables with odd labels.&lt;br /&gt;
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* '''Cosmology''' is the science of the development and ultimate fate of the universe. The joke here may be pertaining to the different models accepted in the field of cosmology. H is the {{w|Hubble's law#Time-dependence of Hubble parameter|Hubble parameter}}, &amp;amp;Omega; is the universal {{w|Friedmann equations#Density parameter|density parameter}}, G is the {{w|gravitational constant}}, and &amp;amp;Lambda; is the {{w|cosmological constant}}.&lt;br /&gt;
&lt;br /&gt;
* The joke about the &amp;quot;truly deep physics equations&amp;quot; is that most of the universal physics equations are simple, almost exceedingly so. One example is Einstein's &amp;lt;math&amp;gt;E = mc^2&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
* The title text is referencing the fact that the electric and magnetic fields are often explained to physics students using an analogy with fluid dynamics, as well as the fact that they do share some similarities (only in terms of mathematical description as three-dimensional vector fields) with fluids. The permittivity constant (represented with ''&amp;amp;epsilon;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) and the permeability constant (represented with ''&amp;amp;mu;''&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;) are coefficients that relate the amount of charge required to cause a specific amount of electric flux in a vacuum and the ability of vacuum to support the formation of magnetic fields, respectively. They appear frequently in Maxwell's equations (the equations that define the electric and magnetic fields in classical mechanics), so Randall is making the joke that any surface integral with them in it automatically is an electromagnetism equation.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Nine equations are listed, three in the top row and two in each of the next three rows. Below each equation there are labels:]&lt;br /&gt;
&lt;br /&gt;
:E=K&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;t+1/2 &amp;amp;rho;vt&amp;lt;sup&amp;gt;2&amp;lt;/sup&amp;gt;&lt;br /&gt;
:All kinematics equations&lt;br /&gt;
&lt;br /&gt;
:K&amp;lt;sub&amp;gt;n&amp;lt;/sub&amp;gt;=&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;i=0&amp;lt;/sub&amp;gt;&amp;amp;sum;&amp;lt;sup&amp;gt;&amp;amp;infin;&amp;lt;/sup&amp;gt;&amp;lt;sub&amp;gt;&amp;amp;pi;=0&amp;lt;/sub&amp;gt;(n-&amp;amp;pi;)(i-e&amp;lt;sup&amp;gt;&amp;amp;pi;-&amp;amp;infin;&amp;lt;/sup&amp;gt;) [K sub n = the summation from i = 0 to infinity of the sum from pi = 0 to infinity of (n - pi) * (i-e^(pi-infinity))]&lt;br /&gt;
:All number theory equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x2202;/&amp;amp;#x2202;t &amp;amp;nabla;&amp;amp;sdot;&amp;amp;rho;=8/23 (&amp;amp;#x222F; &amp;amp;rho; ds dt &amp;amp;sdot; &amp;amp;rho; &amp;amp;#x2202;/&amp;amp;#x2202;&amp;amp;nabla;)&lt;br /&gt;
:All fluid dynamics equations&lt;br /&gt;
&lt;br /&gt;
:|&amp;amp;psi;&amp;lt;sub&amp;gt;x,y&amp;lt;/sub&amp;gt;&amp;amp;#x232a;=A(&amp;amp;psi;)A(|x&amp;amp;#x232a;&amp;amp;#x2297;|y&amp;amp;#x232a;)&lt;br /&gt;
:All quantum mechanics equations&lt;br /&gt;
&lt;br /&gt;
:CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;+OH+HEAT&amp;amp;rarr;H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O+CH&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;+H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;EAT&lt;br /&gt;
:All chemistry equations&lt;br /&gt;
&lt;br /&gt;
:SU(2)U(1)&amp;amp;times;SU(U(2))&lt;br /&gt;
:All quantum gravity equations&lt;br /&gt;
&lt;br /&gt;
:S&amp;lt;sub&amp;gt;g&amp;lt;/sub&amp;gt;=(-1)/(2&amp;amp;epsilon;&amp;amp;#x0304;) i&amp;amp;eth;(&amp;amp;#x302; &amp;amp;xi;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; &amp;amp;#x2a22; p&amp;lt;sub&amp;gt;&amp;amp;epsilon;&amp;lt;/sub&amp;gt; &amp;amp;rho;&amp;lt;sub&amp;gt;v&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;abc&amp;lt;/sup&amp;gt;&amp;amp;sdot;&amp;amp;eta;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt;)&amp;amp;#x302; f&amp;amp;#x0335;&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;0&amp;lt;/sup&amp;gt; &amp;amp;lambda;(&amp;lt;span style=&amp;quot;display:inline-block; -ms-transform:rotate(180deg); -webkit-transform:rotate(180deg); transform:rotate(180deg);&amp;quot;&amp;gt;&amp;amp;xi;&amp;lt;/span&amp;gt;) &amp;amp;psi;(0&amp;lt;sub&amp;gt;a&amp;lt;/sub&amp;gt;)&lt;br /&gt;
:All gauge theory equations&lt;br /&gt;
&lt;br /&gt;
:H(t)+&amp;amp;Omega;+G&amp;amp;sdot;&amp;amp;Lambda; ... &lt;br /&gt;
:[There is a brace linking the three cases together.]&lt;br /&gt;
:... &amp;gt; 0 (Hubble model)&lt;br /&gt;
:... = 0 (Flat sphere model)&lt;br /&gt;
:... &amp;lt; 0 (Bright dark matter model)&lt;br /&gt;
:All cosmology equations&lt;br /&gt;
&lt;br /&gt;
:&amp;amp;#x0124; - u&amp;amp;#x0327;&amp;lt;sub&amp;gt;0&amp;lt;/sub&amp;gt; = 0&lt;br /&gt;
:All truly deep physics equations&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Science]]&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Math]]&lt;br /&gt;
[[Category:Chemistry]]&lt;br /&gt;
[[Category:Astronomy]]&lt;/div&gt;</summary>
		<author><name>RandomBananazz</name></author>	</entry>

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