Apparently GPU's are way above my GPA.
In the next year or two, researchers at CERN's Large Hadron Collider (LHC) should be able to answer one of the most fundamental questions bedeviling physicists: what is the effect of gravity on antimatter? As we all learned back in high school, matter falls to Earth at an acceleration of 9.8 meters per second squared, and …
Feynman conjectured that antimatter is just matter going the other way in time. Let's assume that this conjecture is actually true.
Therefore, from the Big Bang so-called antimatter went the other way ("backwards") in time. That's where it is; 13.77 billion years times two in the other direction. Missing Antimatter problem solved.
Therefore, any locally created antimatter in our half of the Universe will also be going "backwards" in time, and would therefore appear to fall upwards in gravity fields. So, yes. Antimatter appears to be repelled by gravity.
Perhaps this also explains Dark Energy too.
The problem with this explanation is that it requires the future to be pre-determined i.e. fate/destiny.
From our point of view, a particle going 'backwards' through time would appear to get younger as (our) time progresses - so far, so good, but this means that as we continue our course 'forwards' through our time we must reach the point where the observed particle reaches an age of zero, or in other words, its origin.
So when we scrollback to the point where we first observed the particle we would know right then that its creation event must have already occurred in our future. Thus, our future must be pre-defined.
This is not to say that at the Big Bang there wasn't also an opposite direction to time but if so the 'now' in our temporal direction won't be in the same place as 'now' in the opposite temporal direction...
The BB is at the bar char, our 'now' is at x and the opposite direction 'now' is at y, so whilst they can both exist they're in entirely different places; we can only be aware of things that are at 'x'.
Adapting this diagram to illustrate my initial point would give us:
...which implies that the Big Bang has occurred both in our past and in our future. However, the trouble with this is that if the the BB is the _single_ origin of both temporal directions it can't be in more than one temporal place.
Some of your objections can be directed to Richard Feynman, but unfortunately he died rather young (69) in 1988.
All the antimatter particles created at the Big Bang went the other way. We don't run into them, and they don't run into us. That's where they went.
Any antimatter sentient being in our Universe would probably explode before having time to evolve thumbs and corner the stock market.
Subatomic particles have a short list of defining parameters: mass, spin, charge, etc. 'Age' is not on the list. Come to think of it, that's a good point for particles with a short lifespan. How do they know? Interesting...
"Come to think of it, that's a good point for particles with a short lifespan. How do they know? Interesting..."
If I were to try and explain how my big sister has had well over 30 twenty-ninth Birthdays I would die a horrible death. Lots of sub-Atomic particles have anti-particles, maybe they have big sisters too.
"...which implies that the Big Bang has occurred both in our past and in our future."
There is another possibility. The Big Bang we measure in the past is an echo of the Big Bang we foresee in the future.
BitCoin "value" is not transparently timeless, but Energy value is: it travels twice as far in four times as long at maximum speed.
Imagine a virtuous bookkeeper, it is not hard to do, some people are virtuous and a few are no doubt bookkeepers. The virtuous bookkeeper's tallies are true at the time of each quarterly Conference Call and in the Annual Report. Except that "true" in this case means that the virtue, straight line depreciation from the Annual Report backwards to Time Zero (partial fractions 0,.25,.5,.75,1) has been redefined to mean what the CEO wants to hear, and he/she may be a violent psychopath capable of inflicting great pain on bookkeepers, or may be a Mob Boss without a corner office and an otherwise virtuous CPA nephew.
This works fine for the Semantic Web, the "progress" of eCommerce does not depend on the existence or non-existence of Cat Videos. They were not good for much yesterday and have an identical future value. They are a low value Perpetuity. If you celebrate your Birthday early you'll find that the cake is a little smaller, no big deal for the virtuous.
In the real world, a business reckons Profit and Loss as a fraction of Working Capital. Brick shops need to make change, eCommerce retailers don't. A tiny difference day-by-day but the effect is that Capital as reported is a cumulative sum of Capital and Working Capital. The split at 1/2 year is 50%x(whatever) -50%x(100%-whatever). When you have to replace an asset (Earthquake, dead bookkeeper, murdered bookkeeper, etc.), the math gets queer. It is those damn Cat Videos that are impossible to lose. If somebody steals the cash drawer from the Gift Shop at the Taj Mahal, or there is an earthquake in India, the remaining Cat Videos become scarce. Graphically, you can not tell the difference between the two catastrophes.
...because there's something in the setup that I don't understand.
If the anti-hydrogen atoms form a well-collimated beam but the expected drop under gravity is only 10 microns (over what distance and at what velocity?), why goes the detector need to be more than a few cm across? On the other hand, if the beam isn't well collimated, how is the drop of an anti-hydrogen going to be measured with sub-micron accuracy?
Obviously I'm missing something, because there's nothing in the experimental description on the Aegis site to indicate how the trajectory of individual anti-hydrogen atoms can be tracked through the accelerator with that sort of accuracy and nothing to say why the detector surface needs to be on the order of 1m^2 as stated in the article.
@frank ly - no, as normal hydrogen would require an anti-matter photographic plate detector to produce the annihilation event that produces the tracks. How would you mount, scan or otherwise handle such a plate without the whole lab going bye-bye as per the icon?
The today's date makes me suspicious of the authenticity of this story. Also question of how do you accelerate an uncharged anti-hydrogen atom or molecule ?
OK, in small bits.
The beam must be well collimated as it is accelerated and hence, is well monitored to ensure it being so.
Otherwise, one would end up with eroded walls of the accelerator.
So, the beam leaves the accelerator, travels a distance and smacks the target.
The distance to target and velocity of the beam gives the target size. One uses a large target in case there are unanticipated results and to gauge noise.
... and so some are already working on ow to maximise return, see e.g.:
Do Bitcoins make the world go round? On the dynamics of competing crypto-currencies
Stefan Bornholdt, Kim Sneppen
Bitcoins have emerged as a possible competitor to usual currencies, but other crypto-currencies have likewise appeared as competitors to the Bitcoin currency. The expanding market of crypto-currencies now involves capital equivalent to US Dollars, providing academia with an unusual opportunity to study the emergence of value. Here we show that the Bitcoin currency in itself is not special, but may rather be understood as the contemporary dominating crypto-currency that may well be replaced by other currencies. We suggest that perception of value in a social system is generated by a voter-like dynamics, where fashions form and disperse even in the case where information is only exchanged on a pairwise basis between agents.
That sounded so banal and obvious from the abstract (except for the last little bit about pairwise information exchange) that I had to skim the paper. It's actually pretty interesting, and only 4 pages (of actual content; citations run onto page 5). A bit of math but all straightforward stuff. People interested in cryptocurrencies might want to take a look.
A few of their observations: Bitcoin is the most popular cryptocurrency, but not out of line with the rest of the top 10. Cryptocurrencies are an interesting phenomenon for the old economic debates about the origin of money (others have noted this, of course). A Moran process models Bitcoin uptake to a certain extent but there are discrepancies.
And I do enjoy this bit:
Overall, our consideration serves to emphasize the
crypto-currency as a good model-system for the study
of human folly, including the history-dependent random-
ness in assigning what is valuable and what has no value.
Everyone knows that the universe is a composite of matter mixed with a vanishingly small amount of antimatter (that's why there is "something" instead of "nothing", to answer an age-old child's question). We also know that, by definition, antimatter has al the "anti-" properties of matter. Why does this question need investigating any more than does confirming the fact that an anti-electron in a magnetic field travels in a direction opposite to an electron.
Einstein's probable answer to the question, "Does antimatter fall up?":
"Of course. This keeps fewer dishes from breaking when a stack of them is dropped."
Unlike the other fundamental forces (electromagnetism, weak & strong or electro-weak & strong if you prefer) gravity has the peculiar property that it is, so far as we know, only ever an attractive force not a repulsive one. If mass and energy are equivalent (E=mc^2 and all that) then antimatter has positive mass and therefore will be subject to positive gravity. Any other result would tear a big hole in the standard model, at least as far as my admittedly out of date understanding goes.
It would also give anti-matter the equivalent of a negative energy density, which sounds extremely unlikely.
On the other hand, if it does work like this, it suddenly makes a lot of FTL drive designs much more practical.
And they'd run off anti-matter, which would make Star Trek right about the future again.
So, if anti-hydrogen were to meet with anti-oxygen and heat, it would not combine to form anti-water?
The electrical charge is opposite. The rest remains the same, according to all current observations and theory.
It is expected that gravity will attract the antimatter the same way that matter is attracted. As it's not been experimentally done before, it is being done now.
If anti-matter had 'negative' gravity that implies anti-matter and matter repel each other but also (I guess) that anti-matter attracts other anti-matter. If that were the case I would expect the universe would be full of anti-matter stars, planets, even galaxies that are repelling from other galaxies.
(Of course, all the galaxies are moving away form each other anyway, and how could we tell if a galaxy half way across the universe is made of anti-matter?)
It wouldn't be easy to tell from a distance whether a star or even a galaxy was composed of anti-matter. The main give-away would be interaction with the interstellar or intergalactic medium.
If anti-matter really does have negative gravitational mass (most physicists expect it wouldn't, but that doesn't remove the need for experiment), it might have negative inertial mass as well. That would mean that it would move in the opposite direction to any force* imposed on it - so two anti-matter particles would attract gravitationally, but the resultant force would cause them to move apart. This experiment wouldn't eliminate this possibility, since the upward force from Earth's 'anti'-gravity would cause antimatter to fall just like normal matter.
Science fiction writers can use this idea as a space drive, because equal masses of matter and antimatter would 'chase' each other at ever increasing speeds - their mutual repulsion causing them to move in the same direction. There's no violation of energy conservation because the total mass is zero.
* including electromagnetic forces, which doesn't correspond with observation.
If you begin your argument with "Everyone knows...", please back it up with scientific measurement. The reality is, we "know" very little about our universe (about 5% of it to be honest). Without making these measurements, we will never know the properties of antimatter nor be able to unravel the mystery of where it has all gone.
Antimatter behaves like matter going backward in time. Most properties are the same, but the charge is opposite. Other properties, like mass, are expected to be exactly the same. The idea of anti-matter falling up only belongs to journalists (or more likely their editors) trying to come up with catchy headlines. Don't blame them. Blame us readers for being attracted by those headlines!
@Steven Goldfarb: 'The idea of anti-matter falling up only belongs to journalists (or more likely their editors) trying to come up with catchy headlines.'
From the article: "We then measure how much it falls," [the CERN scientist] said, "and it is expected that it [will be on the] order of 10 microns it will fall. Or it may fall up. So if we find that it falls up, this is a big surprise and big discovery."
Not just journalists or editors – scientists, as well.
Quote:anti-matter doesn't act in the normal way as matter
I helped the CERN team make antimatter in the 80's, and we worked towards this eventually exciting experiment for a while.
Antimatter does so far behave exactly like matter, it *is* deflected by a magnetic field for example, admittedly in the OPPOSITE way to that of the equivalent matter. We used a wiggler collimator (post antimatter generator) to filter dump the real-matter that passed/regenerated through the copper target. We ended with an uncooled beam of pbars (antiprotons) that then needed accumulating and cooling ('cold' in terms of difference of momentum) before passing to the other physics experiments.
The LEAR Ring (Low Energy Antiproton Ring) was our plaything in the 80's & 90's - a cute antimatter accelerator that you could even be near whilst it was running! - we did make antihydrogen, but not cold enough to watch for the ultimate question of life, the universe and gravitational direction!
The AD http://en.wikipedia.org/wiki/Antiproton_Decelerator is the successor to LEAR at CERN.
To correlate, if anti-matter has mass (and it should given it's composed of the same kinds of sub-sub-atomic particles as regular matter, just arranged differently, then it should react to gravity in the same way. We're just being sure in this case.
According to prevailing theory, negative matter would fall up, but the same theory holds that negative matter has negative mass and can never exist in our universe just as our matter cannot exist in a universe of negative matter (either would break a large number of fundamental scientific laws if it occurred: conservation of energy, for one thing).
In the mid-60's, Otto Frisch (of atomic bomb (in)fame) built the Sweepnik, which used a laser beam to follow the tracks of particles in photographs of bubble chambers.
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you might want to be careful: one newspaper claimed today that scientists had discovered a new (invisible) eighth colour of the rainbow. But they really had - over two centuries ago: see W. Herschel, "Experiments on the Refrangibility of the Invisible Rays of the Sun", circa 1800. http://www.jstor.org/stable/107057
The reason why it seems unlikely that antimatter falls up is because we do have experimental proof that energy falls down, instead of not falling at all. The Eotvos experiment shows that forms of matter with a high energy content still have exactly the same ratio of gravitational to inertial mass.
Or not. It did occur to me that if I had a pair of anti-gravity boots made of antimatter, and assuming my socks stop my feet from disappearimg in a puff of smoke, not only would they have to have a greater mass than my body does to work, I would also wind up upside down. Hmmm. Back to the drawing board.
One theory I came up with to explain the infamous Russian antigravity experiments with spinning superconductors is that a nearby (and unknown to E.Podklentov) positron emitting isotope source was slowly charging up the disk over time with positrons.
These pairing up into Cooper anti-pairs would thus magnify the effect so even a few hundred would generate a very large detectable a-grav field as long as the superconductor was both cooled and spinning fast enough.
Easy to test, any hospital with a 99m2Tc generator aka Moly Cow should be able to supply a small sample and it should also work with sufficiently large quantities of 40K which is also an antimatter emitting isotope some (0.1%) of the time, making the superconductors large enough and screening out the magnetic fields on axis might be a bit more tricky though.
Antiparticles having negative gravity is actually consistent with M-theory and may in fact explain both the "missing" mass of the Universe and other issues with the Standard Model where gravity is concerned.
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