I am not a physicist, so asking this likely "stupid question" here: In which way are those particles from space "high energy"? Is that all kinetic energy, i. e. being closer to light speed than lower energy particles from space? Or is there another component? Thanks in advance.
Einstein's famous E=mc² equation is actually a special case of the general equation [1]
E²= (mc²)² + (pc)²
Where m is the rest mass of the particle (the mass measured when the particle is stationary relative to the observer) and p is the momentum of the particle.
Therefore when we discuss high-energy particles, we mean they have high-energy associated with their high momentum (velocity).
Typically the comsic rays are near-light speed protons. Although they maybe light nuclei.
Note that in modern terminology, the term "rest mass" is no longer preferred. It is now considered cleaner to use the term mass as a constant. The greater difficulty of accelerating as you get closer to the speed of light is then just a different formula for Newton's second law, instead of a change in the mass ("relativistic mass").
This is all equivalent mathematically, but it seems cleaner in terms of terminology rather than saying that the mass of an object depends on the relative speed to the observer.
We talk about 'high energy' because there's an upper limit to speed (the speed of light), but there's no limit to how much energy something can have. The increase in energy increases mass and speed (and therefore momentum), with it mostly varying mass as you approach the speed of light.
A proton moving at 99.5% the speed of light is not moving much faster than one moving at 99%, but the former has much more energy.
> A proton moving at 99.5% the speed of light is not moving much faster than one moving at 99%, but the former has much more energy
If those were spaceships instead of protons one might wonder, given the large energy difference, if it would be worth spending the energy to go at 99.5% c instead of 99% c.
For a 4.3 lightyear trip, the 99% c ship would take 4.34 years. The 99.5% ship would take 4.32 years. That's only 8 days faster, which at first doesn't seem like it could be worth it. It only knocks about 0.5% off the trip.
But that's from the frame of reference of Earth. From the frame of reference of the ships the time will be shortened due to relativistic time dilation.
The 99% c ship makes the trip in 0.613 years (224 days), and the 99.5% c ship makes the trip in 0.432 years (156 days). That's 30% knocked off the trip--which would mean a substantial savings in supplies for the crew. That might be enough to make the extra energy to get that extra 0.5% speed worth it.
If anyone wants to play around with these kind of things I have a calculator designed to make these kind of special relativity calculations fairly easy. Source here [1], deployed here [2].
Here's how you would use it to get the numbers show above. Enter 299792458 in the "scale" field (which makes it so that the distances are in lightyears and time in years).
Enter the speed of the ship in the velocity field (0.99 or 0.995).
The fields in the calculation rows represent an x and a t in your frame (fields 1 and 2) and an x and a t in the ship's frame (fields 3 and 4).
At any given time two fields are input fields (labeled with ① and ②) and the other two fields are outputs. Enter values in the inputs and it sets the outputs such that the event at the x, t in your frame given by fields 1 and 2 is the same as the event at the x, t in the ship's frame given by fields 3 and 5. (It is assumed that at our x = 0, t = 0 and the ship's x = 0, t = 0 are the same).
You can change which fields are inputs by clicking on the symbol to the left of a field. That will make that field input ①, and the previous ① will become ②.
For finding out how long the 4.3 light year trip takes in the ship's frame, we are looking for when the point that is at x = 4.3 in our frame is at x = 0 in the ship's frame.
So make fields 1 and 3 (our x and ship's x) inputs, and put 4.3 in our x and 0 in the ship's x. Then field 2 (our t) shows when the ship arrives according to our clock, and field 4 (ship's t) shows what time is on the ship's clock.
So in practical terms if that goes through the body - are there external signs? A burn out of nowhere? Cancerous cells? What about CPUs or memory chips? Is it fried or bricked or just some hits flipped?
A single particle ? Not much, it might impact the DNA of a few cells but your body will deal with it, like it does for any kind of DNA damage like sun radiation
I'm not sure why these high energies are unusual or unexpected.
If I spray particles into a chaotic system, I would expect some tiny fraction of them to sling-shot around various attractive bodies, and some tiny fraction of those would be ejected to hit some other galaxy - like us.
It could be gravitational. Anything N>2 is unpredictable, with particles possibly exporting the total energy of the system, leaving everything else stationary (zero angular momentum, gently contracting). The same for electromagnetism.
Of course, there will be an occasional ultra-high-energy cosmic ray particle.
The only limit is the universal red-shift, which imposes a spectral shift on how far away this the particle could originate - but even then, it is just statistics, and it could be a 'lucky' high-energy escape from further away.
Directly, I say, because the objects that are extreme enough to produce such environments are indeed essentially fueled by gravitation energy: supermassive black holes at the centers of galaxies, super nova explosions, colliding neutron stars, ...
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[ 0.29 ms ] story [ 52.4 ms ] threadE²= (mc²)² + (pc)²
Where m is the rest mass of the particle (the mass measured when the particle is stationary relative to the observer) and p is the momentum of the particle.
Therefore when we discuss high-energy particles, we mean they have high-energy associated with their high momentum (velocity).
Typically the comsic rays are near-light speed protons. Although they maybe light nuclei.
[1] https://physics.stackexchange.com/questions/143652/is-e2-mc2...
This is all equivalent mathematically, but it seems cleaner in terms of terminology rather than saying that the mass of an object depends on the relative speed to the observer.
We talk about 'high energy' because there's an upper limit to speed (the speed of light), but there's no limit to how much energy something can have. The increase in energy increases mass and speed (and therefore momentum), with it mostly varying mass as you approach the speed of light.
A proton moving at 99.5% the speed of light is not moving much faster than one moving at 99%, but the former has much more energy.
If those were spaceships instead of protons one might wonder, given the large energy difference, if it would be worth spending the energy to go at 99.5% c instead of 99% c.
For a 4.3 lightyear trip, the 99% c ship would take 4.34 years. The 99.5% ship would take 4.32 years. That's only 8 days faster, which at first doesn't seem like it could be worth it. It only knocks about 0.5% off the trip.
But that's from the frame of reference of Earth. From the frame of reference of the ships the time will be shortened due to relativistic time dilation.
The 99% c ship makes the trip in 0.613 years (224 days), and the 99.5% c ship makes the trip in 0.432 years (156 days). That's 30% knocked off the trip--which would mean a substantial savings in supplies for the crew. That might be enough to make the extra energy to get that extra 0.5% speed worth it.
If anyone wants to play around with these kind of things I have a calculator designed to make these kind of special relativity calculations fairly easy. Source here [1], deployed here [2].
Here's how you would use it to get the numbers show above. Enter 299792458 in the "scale" field (which makes it so that the distances are in lightyears and time in years).
Enter the speed of the ship in the velocity field (0.99 or 0.995).
The fields in the calculation rows represent an x and a t in your frame (fields 1 and 2) and an x and a t in the ship's frame (fields 3 and 4).
At any given time two fields are input fields (labeled with ① and ②) and the other two fields are outputs. Enter values in the inputs and it sets the outputs such that the event at the x, t in your frame given by fields 1 and 2 is the same as the event at the x, t in the ship's frame given by fields 3 and 5. (It is assumed that at our x = 0, t = 0 and the ship's x = 0, t = 0 are the same).
You can change which fields are inputs by clicking on the symbol to the left of a field. That will make that field input ①, and the previous ① will become ②.
For finding out how long the 4.3 light year trip takes in the ship's frame, we are looking for when the point that is at x = 4.3 in our frame is at x = 0 in the ship's frame.
So make fields 1 and 3 (our x and ship's x) inputs, and put 4.3 in our x and 0 in the ship's x. Then field 2 (our t) shows when the ship arrives according to our clock, and field 4 (ship's t) shows what time is on the ship's clock.
[1] https://github.com/tzs/Physics-special-relativity-calculator
[2] https://tzs.github.io/Physics-special-relativity-calculator/
A beam of it ? You'll definitely notice: https://en.wikipedia.org/wiki/Anatoli_Bugorski
If I spray particles into a chaotic system, I would expect some tiny fraction of them to sling-shot around various attractive bodies, and some tiny fraction of those would be ejected to hit some other galaxy - like us.
It could be gravitational. Anything N>2 is unpredictable, with particles possibly exporting the total energy of the system, leaving everything else stationary (zero angular momentum, gently contracting). The same for electromagnetism.
Of course, there will be an occasional ultra-high-energy cosmic ray particle.
The only limit is the universal red-shift, which imposes a spectral shift on how far away this the particle could originate - but even then, it is just statistics, and it could be a 'lucky' high-energy escape from further away.
https://en.m.wikipedia.org/wiki/Fermi_acceleration
Directly, I say, because the objects that are extreme enough to produce such environments are indeed essentially fueled by gravitation energy: supermassive black holes at the centers of galaxies, super nova explosions, colliding neutron stars, ...
https://www.researchgate.net/figure/A-modern-adaption-of-the...