Scientists at Fermilab close in on fifth force of nature

originally posted by: charlyv
a reply to: AlienBorg

When cosmic rays collide with molecules in the upper atmosphere they produce pi mesons that quickly decay to produce muons which in turn decay after 2.2 microseconds to produce electrons/positrons and two types of neutrinos.

If Muons decay after 2.2 microseconds, then at relativistic speed, they can only travel about 235 feet before they decay.
Since they form in the upper atmosphere, how can these muons possibly hit the surface of the earth?

Relativistic speed for muons is 57% of the speed of light. so 186,000 miles per second becomes a relativistic 98,022 miles per second which is 517,556,160 feet per seconds divided by 2,200,000 (which is 2.2 microseconds) = 235 feet

I think you forgot to calculate time dilation and length contraction, comparing the reference frame of the Muon to the reference frame of the Earth. In fact this very thing is one of the confirmations of relativity.

How To Prove Einstein's Relativity In The Palm Of Your Hand

Unstable particles don't experience time as you, an external observer, measures it. They experience time according to their own onboard clocks, which will run slower the closer they move to the speed of light. Time dilates for them, which means that we will observe them living longer than 2.2 microseconds from our reference frame. The faster they move, the farther we'll see them travel.

Also your muon velocity seems off, where did you get that?
Special relativity in the school laboratory: a simple apparatus for cosmic-ray muon detection

Pfeffer and Nir [3] give the average speed of cosmic-ray muons as between 0.994c and 0.998c.

originally posted by: Arbitrageur

originally posted by: charlyv
a reply to: AlienBorg

When cosmic rays collide with molecules in the upper atmosphere they produce pi mesons that quickly decay to produce muons which in turn decay after 2.2 microseconds to produce electrons/positrons and two types of neutrinos.

If Muons decay after 2.2 microseconds, then at relativistic speed, they can only travel about 235 feet before they decay.
Since they form in the upper atmosphere, how can these muons possibly hit the surface of the earth?

Relativistic speed for muons is 57% of the speed of light. so 186,000 miles per second becomes a relativistic 98,022 miles per second which is 517,556,160 feet per seconds divided by 2,200,000 (which is 2.2 microseconds) = 235 feet

I think you forgot to calculate how long a relativistic second is, that is comparing the reference frame of the Muon to the reference frame of the Earth. In fact this very thing is one of the confirmations of general relativity.

How To Prove Einstein's Relativity In The Palm Of Your Hand

Unstable particles don't experience time as you, an external observer, measures it. They experience time according to their own onboard clocks, which will run slower the closer they move to the speed of light. Time dilates for them, which means that we will observe them living longer than 2.2 microseconds from our reference frame. The faster they move, the farther we'll see them travel.

Actually this is very good question often asked in school and university exams. Why we can detect muons at the surface of the earth if muons have just a short lifetime.

There is no fundamental constant that is distance.... otherwise the universe would not be expanding!

originally posted by: combatmaster
There is no fundamental constant that is distance.... otherwise the universe would not be expanding!

The universe may be expanding, but Brooklyn isn't.

The Universe Is Expanding, but Brooklyn isn't

So a meter on Earth will still be a meter on Earth until the sun expands and destroys the Earth 5 billion years from now (or until we change the definition of a meter agains but those changes didn't change a meter much for most practical purposes).

But it does seem odd that we can see light from galaxies that are currently over 30 billion light years away when the universe has only existed for about 14 billion years, because how far should light be able to travel in 14 billion years? Stretching space would explain that.

More Than 30 Billion Light-Years Away, Hubble Captures the Most Distant Galaxy Ever Found

a reply to: Arbitrageur

A meter on Earth is still a meter based on your perspective, which is dependent and based in the expanding universe. So it seems constant to you because you are also expanding with it.

But objectively, it is not a constant, because it is ever expanding. This explains how there is more distance between an atoms nucleus and a human than between a human and the moon kinda thing!

So it has led me to conclude distance doesnt really exist, it is our perception that is limited. there is only mass and volume. maybe im worng im no scientist, but it seems like obvious when you really think about it!

a reply to: AlienBorg

Actually this is very good question often asked in school and university exams. Why we can detect muons at the surface of the earth if muons have just a short lifetime.

Can totally confirm that we still see Muons in experiments buried 2km underground... boy... they don't half light up scintillator. As well as create a spray of neutrons.

originally posted by: combatmaster
a reply to: Arbitrageur

A meter on Earth is still a meter based on your perspective, which is dependent and based in the expanding universe. So it seems constant to you because you are also expanding with it.

But objectively, it is not a constant, because it is ever expanding.

Wrong. Ok I admit posting a hollywood movie clip was not a scientifically reliable source, but I posted it because nonetheless it's true. Here's a more robust explanation of why you're wrong.

This Is Why We Aren't Expanding, Even If The Universe Is

If there's a force binding those objects together that's greater than the background expansion speed, there will be no increase in the distance between them. If there's no increase in distance, there's no effective expansion. At every instant, it's more than counteracted, and so it never gets the additive effect that shows up between the unbound objects. As a result, stable, bound objects can survive unchanged for an eternity in the expanding Universe.

This explains how there is more distance between an atoms nucleus and a human than between a human and the moon kinda thing!

No it doesn't.

a reply to: Arbitrageur
a reply to: AlienBorg

Thank you both for pointing that out and I now understand what I left out.

I got the relativistic speed here:

The average speed of muons is measured to be 1.58 × 108m/s (52.7% of light speed).
Speed and Lifetime of Cosmic-Ray Muons - Chengchao Yuan

So I assumed I could just take that percentage against 186,000 miles per second.

a reply to: Arbitrageur

Thank you for your explanation.

Still doesnt explain the conundrum!!

I reckon since the universe is ever expanding, its not objective to measure distance using light! it would be more accurate to use a mass and volume method instead. I dunno, i guess there is a constant that we use that is constant within our universe. But i reckon what im trying to say is, its not a true constant... it is not THE constant!

originally posted by: combatmaster
a reply to: Arbitrageur

Thank you for your explanation.

Still doesnt explain the conundrum!!

I give up, what conundrum is unexplained? We aren't really sure why space is expanding, so we made up the term dark energy to explain the accelerating expansion, which is presumed to most likely be the result of vacuum energy, but it's not really explained/understood, just observed.

I reckon since the universe is ever expanding, its not objective to measure distance using light! it would be more accurate to use a mass and volume method instead.

It's objective to use light as part of the cosmic distance ladder. When the space stretches, so does light, and because we observe spectral lines in the light from distant galaxies occurring at different frequencies than the spectral lines from our own sun, we can tell how much the spectral lines have shifted. When we first observed these shifts about a century ago, we thought they were Doppler shifts but eventually we figured the really big shifts from really distant galaxies had to be from the expansion of space. So now the math is, the bigger the shift in the spectral lines, the more space has stretched the light, meaning the more the universe has expanded.

That's how we can actually plot distance on this graph based on how much the spectral lines of distant galaxies have shifted:
Redshift

The horizontal axis is z, a measure of how much the spectral lines of the light have shifted, and the vertical axis is distance in billions of light years.

I dunno, i guess there is a constant that we use that is constant within our universe. But i reckon what im trying to say is, its not a true constant... it is not THE constant!

I don't think I ever heard a scientist say a length was constant, and especially not since Einstein came up with relativistic length contraction which says it isn't. But the old length standards weren't traveling at relativistic speeds so length contraction wasn't an issue back then.

What IS constant is the speed of light, and according to relativity, if you have length contraction, the meter can be observed to be different lengths to different observers. So in that case, it's the relativistic length and the relativistic time that change, while the speed of light measured in distance per unit time is constant. Very non-intuitive, but observations confirm it.

originally posted by: charlyv
The average speed of muons is measured to be 1.58 × 108m/s (52.7% of light speed).
Speed and Lifetime of Cosmic-Ray Muons - Chengchao Yuan

So I assumed I could just take that percentage against 186,000 miles per second.

Thanks for that reference.
I'm puzzled why you would choose that particular reference for Muon speed when the authors go to considerable lengths to explain that their measured speed of the muons is incorrect due to equipment malfunction:

yuan-cc.github.io...

However, our result of muons’ speed is much lower than reported results (about 99% c)[13][14].
This discrepancy mainly came from the malfunction of our apparatus instead of the low speed of muons. In fact, we double-checked our setups and procedures for several times and we came to the conclusion that the TAC is malfunctioning

Which also raises the question: Why they would even publish that paper with the result from the malfunctioning equipment, instead of correcting the equipment malfunction and then publishing the correct result?

a reply to: Arbitrageur

Thank you honestly for that long explanation. So i was not wrong, it was not a true constant... everything you said is what i thought but couldnt word. So thank you.

Its actually not that complicated when you think about it.

originally posted by: combatmaster
a reply to: Arbitrageur

Thank you honestly for that long explanation. So i was not wrong, it was not a true constant... everything you said is what i thought but couldnt word. So thank you.

Its actually not that complicated when you think about it.

Relativity is quite complicated.

The reason you gave for length not being constant is you thought the expanding universe would change the size of you and me and everything on Earth. As I tried to explain, that is not correct, because in ordinary everyday use the yardsticks on Earth are not expanding and won't expand in spite of the expansion of other parts of the universe, at least not before the Earth is destroyed 5 billion years from now. So the length of a yardstick is relatively unchanging in everyday use even if it's not classified as a constant by physicists.

The reason they don't call it a constant is when you take your yardstick inside a bullet train going very fast, then the relativistic effect can chage the apparent length of the yardstick to an outside observer, but to you inside the train, the length really hasn't changed. So, has the length really changed? Or is it just a matter of perpective? I would say the length hasn't really changed, the yardstick only appears to be different lengths to different observers because of perspective of their different reference frames, one standing outside the train and one inside the train in that example.

That "change", isn't really a change, I would say it's a difference in observation caused by the different reference frame, and it's actually in the opposite direction to what you said. You said the length depended on the expanding universe, but in the case of relativity it actually contracts rather than expanding. So you were wrong about that, at relativistic speeds the length contracts or shrinks, it's time that expands or "dilates".

What you said was: "A meter on Earth is still a meter based on your perspective, which is dependent and based in the expanding universe. So it seems constant to you because you are also expanding with it. "

If you had said something like this it would have been correct: "The length of a meter observed on Earth is dependent on the reference frame of the observer" That would not be wrong, but I don't think you can claim the length of a meter on earth is dependent and based on the expanding universe and claim that's not wrong. It's wrong. Even in the example on the bullet train, you would be hard pressed to measure the difference in the yardstick length from the observer on the train vs. the observer on the ground since the speed of the train is so slow compared to the speed of light.

Some physicist showed this example of how insignificant this relativity stuff is at non-relativistic speeds, where the train is going 2mph and the sheep walking on it is going 2mph in the same direction.

The total speed of the sheep with respect to the ground is not 4mph exactly, it's a probably immeasurably small amount less than that as the physicist calculated in the illustration, but we can't measure that small a difference, can we? I just mention this to emphasize that the size of the yardstick really doesn't change much even on the bullet train.

a reply to: Arbitrageur

Im sure we can measure it... if we can biuld microchips with transistors at 2nm then im sure we can do wonderous things further.

The way i see it and also the way i see the so called wall that theoretical phycisists have hit is that the universe is like a shattered mirror. Scientists are theorizing and researching with the assumption that they are studying the building blocks of the universe, the way it works! This is wrong! This is a malfunctioning/shattered state. This is the way it is when its not working properly! I believe with this understanding its easier for scientists to do their brain magic.

Imagine, by way of a distorted reflection on a shattered mirror you study the world. You would never understand it.

To put it simply, think of this state of universe/reality as an inevitable result of a malfunction of a base reality that was functioning. Entropy and the construct/perception of time for example are a result of this. The massive amounts of grouped up matter that is dead, empty or otherwise seemingly pointless star systems in an even more massive and seemingly even more pointless ever expanding universe.

Im not a science guy, far from it, but recently i have realized ive been arriving at the same logical conclusions that science has, when thinking about this kinda advanced stuff, simply by working off of the understanding i explained above. its way more intriguing that just a broken mirror, i just put it in a nutshell for you. Im a layman so imagine if real scientists knew, they would advance their understanding of this topic by light years so to speak (no pun intended).

Again, thank you for your input, highly appreciated!

a reply to: Arbitrageur

There exists some excellent education in particle physics in here, for those like me who consider themselves scientifically literate, but certainly not quantum physicists. Thanks to all of the contributors.

a reply to: Arbitrageur

There seems to some sort of confusion on the subject of relativity. Equally confused arguments on why we're not 'expanding' as the universe expands, which according to other member will change our lengths and that is interpreted as length not being a 'constant'.

a reply to: AlienBorg

Im not refuting any science here... im just saying its a 'constant' within our universe.

a reply to: combatmaster
The reason we can't measure the relativistic speed of the sheep is the error bars in the measurement would be larger than any relativistic difference it has when moving at 2 or 4 mph. If it was an advanced clock in a NIST lab instead, it would be possible.

NIST has made some absolutely astounding and impressive relativity measurements that were unthinkable even a few decades ago.

Here we compare two optical atomic clocks to observe time dilation from relative speeds of less than 10 m/s and changes in height of less than 1 m. This sensitivity to small relativistic clock shifts is enabled by recent accuracy improvements...

I don't often hear that broken mirror analogy, but in my signature is a link to a thread where I heard many claims that "scientists are doing it wrong" or something along those lines. First, I admit that's entirely possible in some way. Actually muon subject sort of points to a clue about a universe puzzle that scientists have so far failed to put together. In addition to the "1st generation" electron, and the "2nd generation muon" which is 207 times heavier than the electron, there is also a "3rd generation" negatively charged particle called the Tau which is 3477 times the mass of the electron.

These three generations of those "leptons" is telling us something probably very fundamental and interesting about the universe. Why are there these three generations and why are the particles in the 2nd and 3rd generation progressively so much more massive than the first generation? Maybe these observations are like looking through a shattered mirror, because even though it's pointing to something interesting, it only seems like a piece of the puzzle and only with an unbroken mirror could we see enough to put the puzzle pieces together.

Such an event of first seeing through a broken mirror and later finally putting the puzzle pieces together has already happened in the history of physics and chemistry, in the development of the periodic tables of the elements. In early periodic tables, we could see patterns in how elements behaved which allowed us to organize the periodic table according to those patterns, but long ago we didn't know why those patterns existed, so that too was like looking through a piece from a broken mirror. Eventually we discovered subatomic particles, notably the electron, and then the existence of electron shells, and then fnally with quantum mechanics we were no longer looking at the periodic table as a puzzle piece in a broken mirror, it all started to make sense; why some elements were inert like the noble gases, whose electron shells were full so they didn't want to bind with any other elements, and why other elements bonded the way they did, and so on.

But we've had no such "aha!" moment yet with understanding what the three generations like electron, muon and tau are telling us about nature on a deeper level as happened with the periodic table, unless ErosA433 knows about some new "aha" that I don't. Maybe someday we will understand that too.

a reply to: combatmaster

Your question about why muons are detected at the surface of the earth is easily answered if you try to do a bit of math.

Find how far these muons will travel if let's say their speed is around 99.8% the speed of light and their lifetime is about 2.2microseconds.

Then consider the theory of special relativity and the concept of time dilation. Means that time expands significantly in the muon's frame of reference. Consider the gamma factor and do the calculations.

You will find muons don't travel just a few hundreds meters but tens of thousands of meters. Around 13-15Km and that's why when they start at 13-15km above earth's surface they can reach the surface of the planet and even penetrate it to be found in a depth of 2km below the surface level.

originally posted by: Arbitrageur

originally posted by: charlyv
The average speed of muons is measured to be 1.58 × 108m/s (52.7% of light speed).
Speed and Lifetime of Cosmic-Ray Muons - Chengchao Yuan

So I assumed I could just take that percentage against 186,000 miles per second.

Thanks for that reference.
I'm puzzled why you would choose that particular reference for Muon speed when the authors go to considerable lengths to explain that their measured speed of the muons is incorrect due to equipment malfunction:

yuan-cc.github.io...

However, our result of muons’ speed is much lower than reported results (about 99% c)[13][14].
This discrepancy mainly came from the malfunction of our apparatus instead of the low speed of muons. In fact, we double-checked our setups and procedures for several times and we came to the conclusion that the TAC is malfunctioning

Which also raises the question: Why they would even publish that paper with the result from the malfunctioning equipment, instead of correcting the equipment malfunction and then publishing the correct result?

Why would the publish the paper?

Well firstly its not a peer reviewed paper, it is what appears to be a final year lab / piece of directed research project. The big tell is that they basically write down and explain absolutely everything from near first principles. Even down to the PMT high voltage vs rates... this is an important step to ensure you understand your trigger efficiency but, in a peer reviewed paper, no one would include it, there might be a one line statement regarding calibration or background rates, but thats it. not a section and a plot.

its basically a lab report, not a paper.... still good write up, and for them to figure out that the measurement has to be off because there is something wrong with their TAC system is a pretty interesting find, because yeah, it shows they looked quite closely into if their equipment is working correctly.


The experiment i work on, has a similar thing in which we basically use an RC type circut to perform a constant gradient ramp... this dumps charge into a ADC system which will, fill as a function of time from the ramp. How much charge the ADC reaches is the time.

We do get occational issues where the passives on this system start to change because of heat or age. We do have the ability to alter the ADC calibration to bring things back into expectation... but its never perfect.