 Yeah, very simple. So we adjust conservation law of mass, continuity equation, momentum conservation, and energy equation. But the only difference is that there are two energy equations, because we separate them for electrons and for lattice separately, write them separately. So this is energy equation for electrons. And this is energy equation for ions. So what we have? We have a metal. So this is metal. This is his boundary with vacuum. This is vacuum or water or some transparent media. This is ions and electrons. And this is penetration depth for electromagnetic wave. For optical electromagnetic wave, it's typically something like 50 atomic layers. And now we radiate photons, larger photons, and they are absorbed only by electrons. So initially, we have equal temperatures for electrons and ions. But after heating, electrons become hotter, because they absorb energy. They absorb energy from this term. This is absorption term. And they transfer part of this energy back to the ions. But this transfer is rather slow. Its power is much less than the power of laser. If we use femtosecond lasers, we're very bright flashes. Therefore, they are much hotter than ions. And another important ingredient is this electron heat conduction term. In metal, it is large. And this term transport energy absorbed at the skin depth here into the bulk of the metal. So this is electron heat flux going into the bulk. And it creates some so-called heat affected zone near the surface. It also has nanoscale thickness. But typically, it is something like 5, 10 times more thick than the skin layer. So the skin layer is 10 nanometers. And the heat affected zone is something like 100 nanometers. And here, I just write some simple expression explaining why it is supersonic. In usual conditions, heating is much more slow than the sonic acoustic wave propagation. The velocity, the rates of the heat transfer is usually subsonic, significantly subsonic. But in our case, it is supersonic. Why? This is just due to the fact that the Fermi velocity of electrons which transport this energy is two orders of magnitude higher than the speeds of sun. Therefore, for some time, this velocity, just heat velocity, heat wave propagation velocity, it is larger than the acoustic velocity, which is small because the ion are heavy. Therefore, this heat affected zone is created supersonically. Supersonically means that refraction propagation. And we heat the system. Therefore, we rise pressure just because we rise energy. And we don't have time to expand, to release this energy, to release this pressure, to unload matter. We don't have time because it is supersonic. Therefore, pressure rise and matter became to unload to the vacuum side. And the refraction began to propagate into the bulk. But this heat affected zone is created before. So for a hydrodynamic picture, we just immediately create a heated and pressurized layer. And after that, follow its unloading. So we consider this problem. For example, it is a gold. It is typical situation in water. People illuminated by femtosecond laser. And this process produce nanoparticles somewhere at very late time, after pulse. But how it proceeds? It's still not well known. And we use this equation, just very simple hydrodynamic fundamental equation, to describe the unloading of gold. So gold is heated. It is unloaded into water. And what we see is, this is the pressure profile and density profile. This is density jump on the gold water surface. And it move into water, support the shock wave in the water. This is shock in the water. This is shock-compressed water. This is contact. This is refraction wave. And this is compression wave going into the bulk of gold. And this is refraction wave. So if it will freely refraction, it will be somewhere here. But water decelerating motion. And some layer appears. I call it atmosphere. I will explain why. Where the gold know about existence of water. Outside this layer, gold expand freely without any water. So this unloading produce motion of the contact. The motion of the contact, like a piston, produces shock in the water. And this is shock-compressed water. This is density jump. Because gold is 20 times more dense than water. And this is at the later time, we see this pressure wave. It is rather large amplitude. Something like part of megabar going into the gold. And the shock going into the water. And we produce this, this is condensed matter. This is, therefore, when we expand it significantly, it began to nucleate. It came to decay to small fragments. And this is region where it decayed. Later in time, this is sub-nanosecond stage. Shock goes far away. This is the contact. And here, so this is the contact. This is so-called atmosphere. It's motion is decelerated by water. Therefore, it moves more slowly. But this form region don't know about water. It moves freely. Therefore, it moves faster than the atmosphere. Therefore, it collides with atmosphere from this side. But the amount of mass in this form region is limited. Therefore, after some time, it just, all this mass go into the atmosphere. And after that, only vapor support atmosphere from the rear side. And here, I just show how it looks like. This is one-dimensional simulation. So here, this form region is like just fluktation of density. But this is three-dimensional molecular dynamic simulation. So you see this is atmosphere. And this is this form region for two-time instance. And this fragments of the form fall down. Therefore, the atmosphere becomes thicker. And also, the water is heated. The blue color, I mean, this is bulk water, deep blue. And this is light blue water, which is heated due to atomic-atomic molecular heat conduction in water. It is small. Two orders of magnitude smaller than in metal. But it is enough to heat water near the contact. And this is enlarged fuel. You see this form region, which is attack, this layer. And the temperature dropped down into the bulk. Therefore, the vapor pressure, also, a saturation of vapor pressure drops down as temperature drops down. Therefore, this is vapor. It is dense here. Temperatures are water of 7,000. Kill me, 5,000, 7,000, 8,000, something like this. Near 10,000. Therefore, it is dense here and this dense far away. Here, just I will show this move twice. Here, I won't just pay your attention to this how this form region too fast. So we have liquid fragments. And vapor inside the cavities. They move faster than the atmosphere. Therefore, in astrophysics, such process called accretion. So it accretes on this atmosphere. And why I call this layer atmosphere? Because it is decelerated by water resistance to motion. And thus, we have some effective gravity here. This effective gravity produce density and pressure drop in the atmosphere. Therefore, pressure here is higher than here. And this decelerate, this pressure gradient decelerate the atmosphere. And the shock in water propagate to large distance, up to millimeters and centimeters. And here, I just normalize it. And what I want to emphasize that even for large, very large, when it go far away, it amplitude decay. And it becomes just sonic wave, acoustic wave propagating in water. The bulk models of water is something like 2 GPA. So now it is 2,000. So it is 0.2 GPA. So it is in linear regime. But still, the pressure here and pressure at contact are somehow comparable. So it is 10 times smaller. But it is some 10% value of the pressure at the shock. So the piston contact here and the pressure shock here are connected. And this is how the decay of the pressure takes place. So this is time after heating, short heating. Heating goes very short. Just shorter than one picosecond. And after that, the pressure at the contact boundary fell down. And this is shock. And it decreases. But the rate of decrease is not so high because it is supported by the foam, which attack it and support pressure. But when the foam is exhaled, no more mass in foam. So this support decay. After that, it began to drop faster. But then it is supported by saturation pressure. This is the temperature of atmosphere here in kilocalvine. So it is thousands of Kelvin. And this is saturation pressure for gold. And we see that after this drop, it is supported by the saturation pressure, which is on the backside of the atmosphere. So at the backside, we have saturated pressure evaporated. And it supports the atmosphere, motion of atmosphere at this time interval. And these are velocities of contact, shock wave. And we take some analytical fit. It is necessary for us to calculate deceleration. Because if you numerically calculate it, it will be very inaccurate. Numerically differentiate velocity. And afterwards, we use this expression for lateral instability with viscosity. This is kinematic viscosity and surface tension. Both of the object is very small. It is just 100 micron in the lateral dimension. And in this dimension also, just few micron. Therefore, the scales are very small, just from 10 to 100 nanometers. Therefore, all this surface tension and viscosity terms become very important. And the acceleration we take from the previous, from this. So we take velocity differentiated obtained acceleration, put it here, and calculate the linear gain of lateral instability. So we have typically, this is typical capillary scale. And we have something like 100 times growth. Not large, but not also negligibly small. And the heat is how it developed. Now I want to pay, to attract your attention to this process. So it's just the lateral, damped by viscosity, high viscosity, damped by surface tension, but still it developed due to deceleration. We decelerate by less dense water. We decelerate very dense gold. Therefore, this is typical condition for the lateral instability. And it have time, and it have possibility to grow significantly produced with nanoparticles, which may be after that collected in the experiment. I just heat is the experiment. But it is a lot of such experiments. This is typical, we produce colloids of this very, very small particle, something like 10 nanometer in size. We use it for many application. And now I want to pay your attention to this part, how it developed in time. And this is molecular dynamic simulation with embedded atom method potential developed by Vasily Zhakhovsky for gold. And that's all.