lurker2718 @ lurker2718 @lemmings.world

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2 yr. ago

Ligo provides great science summaries for most publications, here is the one for this.

By comparing the data to these models, we found that these black holes weighed approximately 137 and 103 times the mass of the Sun, respectively. Taking all uncertainties into account, their total mass was likely between 190 and 265 solar masses, dethroning GW190521 as the most massive black hole binary observed so far.
[...]
The merger produced a black hole with a mass likely between 182 and 251 solar masses.

So it seems 137 and 103 solar masses are the best estimates for each single black hole before merger. Due to uncertainty however, their total mass is in the range of 190-265 solar masses, of which 182-251 remain after merger. The rest of mass is emitted as gravitational waves.

What you describe is more like black start, providing power to the grind when it is down. This has to be controlled well, and only a few plants need to be capable of it.

Grid following means something like whatever the grid does, the inverter injects power supporting it. A grid forming generator or inverter also follows the grid somewhat, but tries to get it to an optimal condition. This entails things like voltage control by reactive power, frequency control by operating reserve, fault ride trough capability and so on. Many of those are naturally provided by large conventional power plants using synchronous generators like gas, nuclear or hydro. For inverter based systems, they have to be considered explicitly. For battery storage most are relatively easy to implement, some also in solar inverters. The tech exists, but yes, in some countries the regulations have not kept up with rapid expanse of inverter based power generation in the last years.

As always, there is a relevant xkcd for this: https://xkcd.com/2608/

The AI needs help to cut the loop, perhaps it needs a new set of knives?

Out of interest I did some estimates and it seems that an asymmetry of three billionth of the total thermal radiation would be enough to rotate the probe once over a timescale of 10 years. So if the radioisotope generator has even just a tiny bit of a different infrared brightness on one side, it would turn voyager in a few years.

It needs thrusters, because there are still some small forces acting on the probe. For example, asymmetrical emission thermal radiation may rotate the probe slowly. This accelerated the Pioneer probes somewhat, see Pioneer anomaly. So without correction you can't keep the orientation for years. Every tiny force would accumulate over this timescale.

The thing is, now we have one 1-2 3.7 meter sized antenna on the voyager probes and a 100 meter sized antenna on earth with high transmission power. Signal decays with distance squared. To get the same signal power to the voyager probe assuming an relay in the middle, it would need an 25 meter antenna with the large transmitter/receiver currently on earth on space.

In short it's easier to build a 4 times better transmission system on earth than in an relay in space.

One point where relays are used are mars rovers. There the orbiter has an large antenna and is close to the rover, so you don't need to land the large antenna at the surface.

Edit: fixed antenna diameter

If you haven't read it already, try the new book "Project Hail Mary" also by Andy Weir. I found it even more enthralling.

I was always annoyed by this question for the same reasoning. However, as another person already said, you can sometimes feel it in some part of the body. When feeling bad, it feels like pressure in my stomach, there a a few other.such connections. Now I find it somewhat useful as part of mindfullness.

I do still get annoyed when asked this question, partly because whenever he asks the question i do not feel it anywhere, also it seems irrelevant. But the main reason is probably defiance that this seemingly stupid question of him was sensible all along. So much I had to write this response.

Hopefully, otherwise it may end bad: https://what-if.xkcd.com/6/

No, to orbit the earth at an height of let's say 1000 km you would need a speed of around 7km/s. If you go faster, you don't follow an circular orbit. Wirh around 11km/s you would be so fast to leave the gravity well of earth. The particles in those colliders are almost moving at the speed of light. To be exact, they move only 3.1m/s slower than the speed of light, so almost 300000km/s. They would fly almost straight and would be barely influenced by the gravity well.

In my opinion this is a bit of a narrow view. It definitely holds true for many Christians. But I think some religions like Buddhism may actually help you find a way without guard rails.

The more self-sufficient you can be, the fewer societal resources you will take up, which could then go to someone else in greater need. That's my perspective at least.

But the more self-sufficient you are, the more resources of yourself you need to supply yourself. So you can provide less societal resources. If you do not need to provide clothes for yourself, you have more time caring for elderly, etc.

As another view, the total resources need does not directly change by changing who does what. The advantages of helping each other are in the OP. At some point however, I would think, the overhead of organization grows so large that it may not be worth it anymore. Just think of the amount of work put into "useless" administration in many countries. But in a 30 person village, this is probably negligible.

Edit: Thanks for helping other people on the feet!

I think your post is exactly what is criticized by OP. In the first part of the post it is explicitly stated men should not talk over the fear of women. A message like yours seems to blame people just because they criticize the way of discussion in some places. I think it is obvious that men are influenced in a possible negative way, when they are always seen as danger. At least for me it probably contributed to my low self esteem, especially in all sex/gender related topics. I think, we as men do so much harm, I don't want to take part in this. But i took it to the extreme, so I was ashamed of everything sexual about me. But as OP said, all of this doesn't invalidate the feeling of any woman. But for example this situation here is not governed by fear, still it seems you can't discuss the social effects of this sentiment "against" man, without discrediting the other side. Sure, violence done mainly to women is the most important topic. But if men always get portrayed as danger, I can understand some are open to other, more misogynist worldviews.

Acapellascience (Tim Blais)

Yes. One place in space has different temperatures. I would assume even individual particles are not distributed by a Maxwell distribution, so the concept of temperature is hard to apply. The background radiation has one temperature. If you add the sun, however, you already have a problem as the sun radiation is not in thermal equilibrium. So depending on how you look at it, you get different temperatures. The particles have a high energy, so also a high temperature. But they are so rare, that radiation is the dominant mode of heat transfer and determines the temperature of a thermometer placed in space.

I think it is actually the other way around. You can consider the air inside the balloon to have internal energy from the heat. And additionally you have to make room for the balloon in the atmosphere, so you have removed the atmosphere from the volume the balloon takes, which also needs energy. If you consider both you arrive at the concept of enthalpy (H = U + pV), which is very useful for reactions in the atmosphere as pressure is constant. For this example it is not that useful as outside pressure changes when the balloon rises.

Another way to see it, the pressure has no "real" energy. In a ideal gas, the only energy comes from the kinetic or movement energy of the atoms. Each time a gas molecule is hits the balloon envelope it transfers some momentum. The cumulative effect of the constant collisions is the pressure of the gas. If the balloon is now expanding slowly, each collisions also tranfers some energy, in sum building the work the system has to do to the atmosphere. Leading to a decrease in internal, so "real" energy in the balloon. This corresponds to a decrease in temperature.

The stratosphere is heated not by the ground but directly from solar radiation leading to higher power input at the upper layers. So the top is hotter and now convection never starts and you get no cooling of the air when rising.

While I agree in general, one point is a bit to simplified in my opinion

In other words, there are fewer air molecules per cubic foot (volume of air). The molecules are farther apart and can hold less heat energy. Because "heat" is what we say when we mean molecules are moving around.

Less molecules mean less heat, it has nothing to do with the temperature, if you just decrease the density by removing half the molecules, you have the same temperature.

It cools down because it expands adiabatically. Consider a very thin balloon filled with air which is warmer than the surrounding. This now rises up, but as it does, the pressure decreases, causing the balloon to expand. During this expansion, the balloon transfers energy away from itself, because it has to push away air, to make room for expanding in the surrounding. This work cools the air inside the balloon. Assuming the air inside is dry, it would cool around 10 °C per km it rises. Now if you think about it, the balloon just stopped the inside from mixing with the outside. If you look at a large "piece" of air, it does not mix very fast, so you can remove the balloon and just consider what happens with warm air heated from the ground.

Now this does not mean, it has to be cooler when higher up. The same points hold, inside a house, but there it is often warmer when higher.

The best explaination is when looking where the heat comes from and goes too from the air. The atmosphere is mostly heated from the surface of earth, so the bottom and cooled from the upper layers. So naturally it gets hotter where it is heated. The question is now by how much? There are three modes of heat transfer in the atmosphere: radiation, conduction and convection. The first two are very slow. Connection is fast but has limits. Consider the piece of air, if it rises, it cools. So at some place it may be the same temperature as the surrounding air, so it stops rising. This means the convection works only when the air gets cooler by 10 °C/km going up (~6.5°C when the air is moist and precipation happens). So this temperature gradient is observable very often.

Yes, the file itself (so the data and inode) is not gone as long as the handles live on. Only the reference is gone. You canstill recover the file. https://superuser.com/questions/283102/how-to-recover-deleted-file-if-it-is-still-opened-by-some-process#600743