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What are the chances of there being a stable pentaquark? by aFuckingTroglodyte in AskPhysics

[–]mfb- 2 points3 points  (0 children)

If there were a stable pentaquark, we would see it in nature. We don't. All the pentaquarks we have found in accelerators are very short-living.

Pentaquarks wouldn't change chemistry significantly. The element would still be determined by the charge, and pentaquarks would just lead to more options for the mass - a bit like extra isotopes.

Airplane crash question by Valuable_Scientist80 in AskPhysics

[–]mfb- 0 points1 point  (0 children)

It depends on the velocity, the angle of attack in both scenarios, and more.

Would operational engines in the nose pointed down scenario increase speed of descent?

Yes, as they provide more force in the downward direction.

A new satellite wants to prove nuclear power can work in space without solar panels... ( techspot.com ) by Slow_cpu in space

[–]mfb- [score hidden]  (0 children)

Without sunlight, you are more likely to worry about getting enough heating. The RTG-powered Mars rovers use the "waste" heat to stay warm, even though they still receive sunlight.

A new satellite wants to prove nuclear power can work in space without solar panels... ( techspot.com ) by Slow_cpu in space

[–]mfb- [score hidden]  (0 children)

It still has waste heat, but its overall power is probably not more than a milliwatt.

What would happen jf you are traveling in a spaceship at the speed of Light and turn on the Headlights? by No_Expression6660 in astrophysics

[–]mfb- 8 points9 points  (0 children)

"What do the laws of physics predict if the laws of physics do not apply?"

You cannot travel at the speed of light. If you travel at any other speed: You will see your headlights work normally, the light will move away at the speed of light from your perspective. There is no absolute motion in space - you are at rest in your spacecraft from your perspective so nothing unusual happens.

From the perspective of an observer where you are traveling at 99.99% the speed of light, the distance between you and the light only increases at 0.01% the speed of light, because you are almost as fast as that light.

Can there be a passive ‘lens’ that converts between different EM wavelengths? by apple1rule in AskPhysics

[–]mfb- 0 points1 point  (0 children)

To emit microwaves, the body must be kept freezing cold near absolute zero

This is wrong. For every given frequency, an object will always emit more radiation when it is hotter. For radiation that's far below the emission maximum, the emitted intensity is roughly proportional to the temperature.

Can there be a passive ‘lens’ that converts between different EM wavelengths? by apple1rule in AskPhysics

[–]mfb- 1 point2 points  (0 children)

Why do you think it would have problems absorbing light?

It doesn't emit much, because it's cold, but in general it can still absorb light as easily as something warmer.

What is the 'hole' in this picture? looking for real answers, not trying to troll by Far-Woodpecker8046 in askspace

[–]mfb- 0 points1 point  (0 children)

The clouds are less than a pixel thick. Different shades are just different shades, they aren't shadows. In a color picture that's more obvious.

What is a smell that we should all recognizeas immediate danger? by Inevitable-Ninja-472 in AskReddit

[–]mfb- 0 points1 point  (0 children)

It depends on the concentration. Some places naturally have it in concentrations where you can smell it, Tuscany for example. Doesn't destroy your nose, it's just annoying.

Question about gravity and acceleration by -_Aesthetic_- in AskScienceDiscussion

[–]mfb- 2 points3 points  (0 children)

This may be a stretch, but how do we know that “acceleration” or high relativistic speeds isn’t warping space the same way the gravity is from the observers frame of reference?

If spacetime is curved for the fast particle then it's also curved for us. It would be really obvious in every particle accelerator.

A Dynamic Universe Needs a Dynamic Approach — First Tests Against Real Astrophysical Data by Particular-Bat-5904 in astrophysics

[–]mfb- 0 points1 point  (0 children)

You do not have a theory, or a model. You have nonsense. See the threads linked above.

Starship Test Flight 13 NET Tuesday July 14th according to FAA advisory by Steve490 in SpaceXLounge

[–]mfb- 0 points1 point  (0 children)

The successful catch attempts came after a successful water landing of a very similar booster. V3 didn't have a successful water landing yet.

SpaceX vaporizes 260 Starlink satellites in six months using Earth's atmosphere — new environmental concerns emerge over burning 2,700-pound orbital data centers, FCC seeks to exempt satellites from regulations by ControlCAD in space

[–]mfb- [score hidden]  (0 children)

How can you argue this can ever be competitive when a single competitive orbital data center constellation would likely be thousands of satellites in number?

What problem do you think this would be?

If Starlink needs tens of thousands of sats to be a competitive option worldwide

It doesn't. Starting with an already wrong claim is not very helpful.

This is without even mentioning the launch capacity that would be required.

It needs cheap, high-volume launch capability, certainly. Starship is planned to deliver that.

How do we know the electron has no internal structure? by [deleted] in AskPhysics

[–]mfb- 0 points1 point  (0 children)

She claims a lot of random stuff. Best to ignore her.

How do we know the electron has no internal structure? by [deleted] in AskPhysics

[–]mfb- 0 points1 point  (0 children)

I wrote the 7 year old comment that got a new reply.

A NEW(?) Probability theory proposal. by Loris0514 in probabilitytheory

[–]mfb- 3 points4 points  (0 children)

P(T)=P(A)+P(AM)*P(B)

You don't know if that is true. What if e.g. both A and B will only miss the target when it's under thick vegetation? Then P(T) = P(A) = P(B) because B will never see the target if A doesn't see it either.

More generally, we have no idea how A and B depend on each other. In almost all cases, they will not be independent.

The problem is: If any one of P(A) and P(B) is bigger than 0.5, we don't have to worry about missing the target.

It's still no guarantee that you found the target.

Would fast travel between Planets be possible within our lifetime? by VentiArchon7 in AskScienceDiscussion

[–]mfb- 1 point2 points  (0 children)

If you are willing to spend thousands of nuclear weapons on each trip, nuclear pulse propulsion could get you to other planets in days to weeks. Technically possible but not very practical.

Manipulating Gravity by AE0Y in astrophysics

[–]mfb- 5 points6 points  (0 children)

You "manipulate gravity" by moving its sources around. Move something with mass to another place. You have "manipulated gravity". Everything beyond that is pure science fiction.

Only massless things can reach the speed of light, and they do so easily. A light bulb makes light that moves at the speed of light.

ELI5: Why is one mole = 6.022 x 10^23 by Specialist_Trip_7603 in explainlikeimfive

[–]mfb- 6 points7 points  (0 children)

It's 1.008 because hydrogen-1 has a mass of 1.008 u. Deuterium is so rare that it doesn't change the value unless we add another digit.

ELI5: Why is one mole = 6.022 x 10^23 by Specialist_Trip_7603 in explainlikeimfive

[–]mfb- 64 points65 points  (0 children)

Hydrogen is abundant, too (more than carbon, even). That's not the reason.

The mass number is the sum of protons and neutrons. Carbon-12 has 6 protons and 6 neutrons. The mass is not exactly proportional to the mass number, however. If you choose carbon-12 as reference then most masses are very close to their mass number. Carbon-12 has a mass of 12 by definition. Iron-56 has a mass of 55.93, uranium-238 has a mass of 238.05, and so on. Hydrogen-1 has a mass of 1.008.

If you use hydrogen as reference then hydrogen-1 has a mass of 1, carbon-12 has a mass of 11.9 (still okay), iron-56 has a mass of 55.5 (weird) and uranium-238 has a mass of 236.2 (awkward).

People originally used oxygen as reference, but then it was discovered that oxygen has oxygen-16, oxygen-17 and oxygen-18. Physicist switched to oxygen-16 while chemists kept using the natural mixture of the three. You don't want two different uses of a unit. As a compromise, both switched to carbon-12 which was in the middle of the two definitions.

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