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  #2141  
Old 08.04.2021, 22:05
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Re: Coronavirus

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Happy to be of service.

Trying to take my mind off the pandemic I have been reading a dumbed-down scientific article on the muons — elementary particles similar to electrons - which are now believed by some to travel around surrounded by a cloud of smaller particles that randomly flick into and out of existence.
It is becoming clearer why the brainier folks from my youth who went into particle physics became regular visitors to what used to be known as mental hospitals.
Well. https://www.space.com/7193-death-rays-space-bad.html

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At sea level, the majority of cosmic ray secondaries are highly penetrating muons. About 10,000 muons pass through our bodies every minute. Some of these muons will ionize molecules as they go through our flesh, occasionally leading to genetic mutations that may be harmful.27 Aug 2009
That's twelve years ago. How are you doing? Do your buddies think about this too much?
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Hope by next Christmas there will masks with integrated drinking straws.
Of course.

Thanks for the muons. I will try to sleep now. And not try to think why something that lives for 2.2 microsec makes a difference.
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  #2142  
Old 08.04.2021, 23:22
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Re: Coronavirus

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And not try to think why something that lives for 2.2 microsec makes a difference.
Somebody might ask how the muons make it to the ground from the upper atmosphere (more than 10km up) if they live such a short time. They travel close to the speed of light (0.9999c), but even at that speed they'd only travel 0.6km.

Muons are a nice demonstration of time dilation (from our perspective) or length contraction (from its perspective) as predicted by Einstein's special theory of relativity. From our perspective, they can travel 42km; from its perspective, it only has to travel 0.14km.

You can actually detect cosmic-ray muons using cheap geiger counters from Banggood. Get two of them and stack them together separated by a sheet of lead. Gamma rays from environmental radioactivity don't have the energy to pass through the lead (and if they can - worry), but muons do. So any time they 'click' together, it's a muon and effectively came from the stars (or more accurately, its parent did).
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  #2143  
Old 09.04.2021, 20:57
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Re: Coronavirus

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Somebody might ask how the muons make it to the ground from the upper atmosphere (more than 10km up) if they live such a short time. They travel close to the speed of light (0.9999c), but even at that speed they'd only travel 0.6km.

Muons are a nice demonstration of time dilation (from our perspective) or length contraction (from its perspective) as predicted by Einstein's special theory of relativity. From our perspective, they can travel 42km; from its perspective, it only has to travel 0.14km.

You can actually detect cosmic-ray muons using cheap geiger counters from Banggood. Get two of them and stack them together separated by a sheet of lead. Gamma rays from environmental radioactivity don't have the energy to pass through the lead (and if they can - worry), but muons do. So any time they 'click' together, it's a muon and effectively came from the stars (or more accurately, its parent did).
How would you know that there are "generations" of them?

When you talked about "their time perspective" and "our time perspective" of their travel perception...that only matters in reference to distance travelled, right? Which is again different. It makes sense.
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  #2144  
Old 09.04.2021, 21:42
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Re: Coronavirus

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And not try to think why something that lives for 2.2 microsec makes a difference.
As was mentioned, Muons travel at relativistic speeds, they experience time dilation so the short 2.2 micro secs life is not really an issue.
One practical application is "muon scanning", currently in use in Fukushima to look through the reactor's concrete walls to accurately locate the reactor cores, or what remains of them, without risking radioactive contamination for the workers.

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How would you know that there are "generations" of them?
Each generation is a division of the elementary particles. The divided particles can be identified.
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  #2145  
Old 10.04.2021, 14:07
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Re: Coronavirus

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When you talked about "their time perspective" and "our time perspective" of their travel perception...that only matters in reference to distance travelled, right? Which is again different. It makes sense.
Yes, essentially; given that we're also talking about about 'distance travelled' through time.

There's a reasonably intuitive explanation of time dilation that I often dine out on, which is:

- Reality can be thought of as a four-dimensional entity (3 of space and 1 of time).

- All objects are travelling at the speed of light (including us).

- Objects with mass who are at rest (with respect to another object) are travelling through time at the speed of light; objects without mass are travelling through space at the speed of light (and are not travelling at all through time).

- When an object travels through space, it 'steals' something from the time dimension and so is travelling more slowly through that dimension in order that its total velocity is still the speed of light. This is basically Pythagoras' Theorem in four dimensions where you can think of total distance travelled as being sqrt(x^2 + y^2 + z^2 + t^2) (except that special relativity changes the sign of the t dimension for reasons beyond the scope of this post).
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  #2146  
Old 15.04.2021, 22:36
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Re: Ask a Scientist

The NASA Mars lander InSight’s solar panels are accumulating too much dust, preventing the lander from charging its batteries so risking a premature end to the mission, it is in emergency hibernation.

NASA's Opportunity rover stopped working in 2018 when its solar panels accumulated too much dust.

My question is why was InSight not equipped with some means to clean the solar panels, relying on winds to clear the dust is somewhat primitive.
There are many automatic solar panel cleaning systems available commercially which do not require water.
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  #2147  
Old 15.04.2021, 23:40
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Re: Coronavirus

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Yes, essentially; given that we're also talking about about 'distance travelled' through time.

There's a reasonably intuitive explanation of time dilation that I often dine out on, which is:

- Reality can be thought of as a four-dimensional entity (3 of space and 1 of time).
The "1 of time" being actually multiple. Which you mentioned bellow. It makes it multiple T, but specific. Right? It's logical.

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- All objects are travelling at the speed of light (including us).

- Objects with mass who are at rest (with respect to another object) are travelling through time at the speed of light; objects without mass are travelling through space at the speed of light (and are not travelling at all through time).

- When an object travels through space, it 'steals' something from the time dimension and so is travelling more slowly through that dimension in order that its total velocity is still the speed of light. This is basically Pythagoras' Theorem in four dimensions where you can think of total distance travelled as being sqrt(x^2 + y^2 + z^2 + t^2) (except that special relativity changes the sign of the t dimension for reasons beyond the scope of this post).
There is no more time for my uncle since 1700.

I can't even go to his funeral.
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  #2148  
Old 04.05.2021, 15:17
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Re: Ask a Scientist

Some more interesting pictures from Nasa's Mars lander.:


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