Samuel Hapák

Sorted by New

# Wiki Contributions

I guess the didn’t have their programming class yet😂

If you wrote a C program and it doesn’t do what you predicted, would you assume that your compiler is broken or that you made a mistake? If I got a dollar for every time someone wrongly complained that “there is a bug in compiler”…

World is complex. We use theory to build models describing the reality and compare their predictions with experiment. If you notice mismatch between model and experiment, it might be a problem with:

You have to further dissect and understand the root cause of the mismatch before you make any judgement.

Run away while you still can. Yeah, it’s scary. And heartbreaking. But you might not have that opportunity later on.

Take everyone with you whom you can.

You don’t have to run to some extremely different country/culture. There is lots of relatively wealthy Slavic countries in the Central Europe.

And talented programmers can always find job here.

Let me know if you need help with that.

The plug map is wrong. Gibraltar is using British plugs and should be purple.

Well, the correct question is “What is energy”. And the answer is that energy is some number that we can compute for any physical system and it doesn’t change no matter what as long as the system is reasonably isolated from its surroundings. Kinetic energy is just a portion of this quantity we can compute for something that is moving.

It’s not very intuitive honestly. The best explanation for what energy is I ever read is this one from Feynman:

https://www.feynmanlectures.caltech.edu/I_04.html

It feels to me that you lack a good intuition for how kinetic energy, momentum conservation,, Newton laws, and Galileo's relativity all play together and this is causing you confusion.

Relativity says that there is no objective notion of "being still". We can't objectively distinguish between being still and moving at constant velocity (same speed, same direction).

2nd Newton law: Force is equal to mass times acceleration: .

3nd Newton law: All forces in the nature exhibit the property that if object A acts on B with a force F, then B acts on A with exactly opposite force.

1st Newton law is boring, it just says that if F = 0, then a = 0.

Force and Energy are tied together through the concept of work which says that change in objects energy = work received by that object. And formula for work is , notice the dot product here! Force perpendicular to movement doesn't make any impact on energy.

Putting all of this together, it's useful for you to do following exercises:

1. Try to derive the formula for kinetic energy.
2. Try to derive the formula for potential energy in the gravitational field of Earth near the surface (neglecting change of gravitational force with height).
3. Try to derive the law of conservation of momentum.

Once you do the three above, I have a tricky paradox problem for you to solve:

Imagine two cars driving on the road with the speed . Suddenly the first car accelerates to double the speed, thus travelling . This naturally required consumption of energy in the form of fuel. The change in kinetic energy was:  and this should somehow correspond to the amount of the fuel consumed.

However, from the point of the view of the second driver, the car was starting still and accelerated to the velocity , thus the change in energy is simply .

But, this is paradox. It's not possible that the car would spend 3 times less fuel from the point of view of the other car than from the point of view of the observer standing still on the ground.

That's an excellent question!

Change in energy  must equal work done on the moving body .

Now, work is force over distance

But we also know that force is mass times acceleration, thus .

If you have a body moving under the influence of constant force  over time , starting from the speed 0, it will have a speed  at the end. It's easy to see that the average speed it travels will be  though and thus the distance travelled will be .

Now, the kinetic energy equals work and thus .

Surely. You just need to make some prior on the 3rd. Note, that the 3rd hypothesis is something along the lines of “there is some other model besides Boltzmann hypothesis or Boltzmann brain”, not a specific hypothesis. It can be big bang, god created the universe, or we live inside simulation. Whatever.

Now, you would have to assign unreasonably small prior to this for it not to end up many orders of magnitude more probable than either of Boltzmann Hypothesis or Brain.

I understand your post as trying to argue that Boltzmann hypothesis is more probable than the Boltzmann brain because our subjective experiences are consistent with physical laws.

If that’s the case, your conclusions are wrong. Boltzmann brain is still more probable in this scenario. The mistake you make is excluding the 3rd option that the reality we experience is objective for some other reason (a reason we might not understand yet).

Now, your post is a good argument in favor of 3rd option and against both Boltzmann brain and Boltzmann hypothesis.

Thank you for writing this.

I always felt lots of empathy to all the people in my out-group[1]. Yeah, they believe to a bunch of wrong ideas for dubious reasons. So? My in-group usually believes a bunch of right ideas for similarly dubious reasons! They have no moral high-ground to claim the truth. Often, the out-group has better ideas to believe what they do than my in-group despite being wrong about the end result.

I actually think that it's worse when people are right for the wrong reasons than if they are wrong. In the latter case, there is at least a chance that reality will slap them into face eventually.

1. ^

Out-group here is strongly topic dependent. Pretty much for every topic the in-group and out-group looks different to me.

I don’t think it’s much grey. It’s not the question of whether you are doing perfect job protecting your identity, but are you even trying?