Slashdot Mirror
Reverse Time Could Explain Dark Matter
idot writes "According to Lawrence Schulman of Clarkson University, who will get his work published in the Physical Review Letters,
the universe could contain reverse-time regions. The article from New Scientist says that this phenomenon could explain the yet mysterious dark matter. " The reverse time regions can help explain the "dark matter" problem because, as potential relics from the future, stars could have re-ignited under The Big Crunch and while we wouldn't see them, we would feel their gravity. Needless to say, more details will be needed then this small article.
So just by flying a spacecraft in one of these regions, I can go back in time to any point, and possibly change history?
Seeing as there wasn't a link - for more info, look at http://www.newscientist.com /ns/19991127/newsstory3.html
sounds fascinating, but we have a few more details?
Also, would stuff like this be observable? ie what effects would something like this have?
So even though your post looks like it's first, the truth is I posted this reply before you posted. :-)
does that mean i can enjoy that ever so tasty eggplant parm sub again?!?
waiting and waiting
This seems kind of vacuous... it's what I hate about New Scientist... it often tries to avoid any details that might ruin a sensational piece. No mechanism or evidence or theoretical reasoning is proposed here.... just the laws as we currently understand them don't prohibit this sort of thing.
That said... could this reverse time be like a reflection of a wave in time (rather than in space) off the big crunch? does all time just reverse, and thus there'd be a big crunch even if omega >= 1 and the universe is flat or open? Hmmm...
-- "Those who cast the votes decide nothing. Those who count the votes decide everything." -Joseph Stalin
Does this mean that, the problems with getting there notwithstanding, I could hop into one of these reverse-time zones, hang around for a while, and come out earlier than when I went in? The implications of that are hardly trivial...
I belief he even made a bet on this and lost in the book and movie "A brief history of time".
now I can finally open my own Millways franchise!
...and this way, the paint won't peel on your brand new spaceship. I suppose someone else will "bublish" a book on how to get there.
http://xxx.lanl.gov/abs/cond-mat/9911101
I don't understand the physics ... but I find the idea that local dark matter (yes, within our own galaxy) may be remnants of stars from a far-future universe very unlikely.
Michael Richmond "This is the heart that broke my finger."
mwrsps@rit.edu http://stupendous.rit.edu
Being in real, positive time that is...you gotta burp to do that.
Finally, Schulman's calculations haven't been published yet, but the New Scientist article plays like a passage from Einstein's Dreams. Throw in some Feynman and some decade-old cosmological theories, and we get an explanation for dark matter? Seems awfully unlikely to me.
I thought all the properties for an anti-particle were the same as the particle going backwards in time. So, wouldn't this just be the same thing as large chunks of anti-matter? Or am I just missing something?
.emit esrever ni eveileb t'nod I !hsibbur fo daol a tahW
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Yeah, that was the one where Rimmer and Kryten fall through a swirly thing and end up on Earth with time reversed, right? Geez, that's an older episode; I'd have thought the New Scientist writers would have seen it by now. Maybe they were just watching PBS late one night and caught a rerun...
I'll add this to the known list of accomplishments:
1) 1-2-3 Jello (remember that?)
2) Get Teflon to stick to pans
3) Artificial blood
4) Clarkson Packet Drivers (now Crynwr?)
5) Galahad!
6) The great sinking science center
Any other CU people out there that can add to this?
-- Ever notice that fast-burning fuse looks exactly the same as slow-burning fuse? I didn't... (Edgar Montrose)
As said in the article(New Scientist),the reverse time region needs an opposite of the Big Bang called the Big Crunch. But will a Big Crunch occur ?? Out of the 3 models by of non-static Universe, Big Crunch is the end-effect of just one of the models, the other being Ever Expanding and just exanding enough to avoid a Big Crunch.
So questions arises, will there be a Big Crunch ??
Manifest
... "follow me" the wise man said, but he walked behind
2. He thanks you for warning him earlier
3. You travel back in time and warn him
For those interested it is the easiest way of getting time travel. One day you come home and find all the plans for a time machine - you build it and then return to leave the plans for yourself (the exact pieces of paper)
Question: Where does the matter for the plans come from.
Does your head hurt yet ;)
someone to lazy to create an account
Of course, since we can only imagine the consequences if one could travel backwards in time, it's kind of hard to actually come to any conclusions as to what would happen.
But, in your example, you could make it work if you looked at it this way:
1. You know how to travel through time.
2. Your sister gets bit by a møøse.
3. You travel back in time (and as such, enter into a new timeline/quantum universe/whatever) and save her.
4. Your sister doesn't get bit by a møøse.
5. You celebrate by taking a vacation to Sweden, where you experience the løveli lakes and the wonderful telephone system.
Sure, ideas like timelines or quantum universes are far-fetched. Just theory. Then again, so is time travel, given to our current knowledge. Who knows what's possible?
4) Clarkson Packet Drivers (now Crynwr?)
5)
Don't piss off The Angry Economist
After reading this story, it states that, 'Schulman suggests that they may be relics from the far future. This possibility requires that the expanding Universe eventually starts to contract into a "big crunch". In such a situation, the so-called "thermodynamic arrow of time" may reverse during the contraction, creating order out of chaos--an idea first pro- posed by Thomas Gold of Cornell University. "Because of the opposite-running time, anyone around in this phase would actually see the contraction as an expansion," says Schulman.'
Maybe this could help the explanantions of the big bang and expanding universe theories and how the universe actually came in existence. Or does it just go in a continuous loop of expanding and contacting. Any thoughts?
"... you should have used the Preview button".
4) Clarkson Packet Drivers (now Crynwr?)
5) Galahad!
Don't piss off The Angry Economist
first we get the universe is flat and now we get this reverse time anomaly .so now we have a flat universe that has pockets of time that move in reverse to the general flow of time. this somehow coexist with this flat universe where time is generally moving forwards . So what dose this do to the fabric of space ?
music the paint
dancefloor the canvas
Music the Paint dancefloor the canvas your body the brush
I believe the evidence of the newer deep space hubble telescope data suggests that there won't be a big crunch. Suggests... Anyway, the VERY far away clusters being observed (around 9 billion light years away)by hubble seem to be much larger and dense than the ones near the center of the known universe, which of course suggests that things might just keep expanding..
Talk about making a complex situation even more complex. Shouldn't it be a point to try to simply the dark matter quandry instead of introducing even more unproven theories and variables? Reverse time? Come on. Saying dark matter is made of light absorbing Jello floating in space holds just about as much water as this reverse time argument. "One minute, and Clarkson still sucks!"
form Piers Anthony has a character than does this.
"Bearing an Hourglass" IIRC.
Basically all the gods of yore are roles taken over by mortals of various means (Death, War, Nature, Time, Fate).
While the Time guy does have the power to stop time he has the curse of having to live backwards, effectively starting at his current age and continuing until he turns into a baby then disappears. The book actually had Satan lead him to an anti-matter field where he could live his life "normally". Some light fiction.
Regardless, I think it quite likely that such matter exists. Remember the Universe is a very big, very old place, all sort of strange things have happened (cough*life*cough) and most anything is possible, so...
+&x
Please use time puns which do not resemble spelling errors. Then we'll know when to complain about that there than then confusion which thou throw.
So if time is reversed...does that mean that all the biological functions would be reversed too. So in theory I can come out younger than I was when I went in.
I beleive the fitting comment for a story such as this would be "Last Post!"
=]
How do you get something "bublished" anyway?
--------
It's OK to be social, just don't tell anyone about it.
Someone finds the robot's arm, uses it to build Skynet.
Wow, I never realized that was how SkyNet got built. I thought it was some kind of defense computer network gone wild, or at the least Micorsoft Windows 2010 beta (Are you sure you want to delete humanity? Yes, No, Cancel).
George
Think about it. If we were actually in a reverse time region then we would be in the contracting phase of the big crunch but simply watching it happen in reverse. This would explain the relative abundance of dark matter with respect to ordinary matter, simply because the amount of time left before the crunch would be much less than the amount since the true big bang, so it would make since for the majority of matter to be dark. Any thoughts?
Have you ever held a phone in each hand, each with a different phone number, and have one call the other? Then you hold them close to each other with the mouthpiece of one over the earpiece of the other, for both phones, then bang them into each other and maintain their physical distance between each other at about half an inch. It will cause the sound of them being smacked into each other to repeat infinitely.
Anyone remember the last episode of Star Trek TNG? It was about a patch of 'Anti-Time' in which time moved backwards relative to our perception of time.
There was another episode, in which the Enterprise came across regions of space inwhich the passage of time was moving incredibly slowly relative to normal time, and thus everything seemed motionless. In fact they even managed to move time completely backwards, thereby saving the day. I'm sure there more episodes like this.
Far to insightful to be 'just a coincidence'. I therefor submit that Gene Roddenberry is in fact an enlightened alien from the deep deep future...
Do you really believe that this exists? Has anything ever been proven or at all practiced? Don't you think that if people traveled back in time that we would know about it? That is no proof, but I may believe that more than any other thing I've heard on the subject.
I believe that time is a measurement, plain and simple. It is the measurement of movement. Just like meters measure distance and grams measure weight. Time is just a mesurement.
If meters were non-existant then the whole world would be zero dimentional; if the grams were non-existant then the whole world would have no weight; if time did not exist then the whole world would not be able to move, it would exist anywhere and everywhere all at the same time.
I will attempt to explain. Take a step. Now you are elsewhere. Were you not here before? Are you there now? Of course not. Remove the time aspect, now you can no longer be in one area or another. Because if you move there was a difference in where you were which could only be reconciled with a time difference. In fact, you do not need to actually move, just the ability to move alone would be a proof that time exists. Therefore, if time did exists, you, and everyone for that matter, would have to be everywhere at once. No thought, movement, or anything could exist, because that would mean that time existed.
Well, time would seem to exist. But, IMNSHO (In My Not-So-Humble Opinion), as a measurement, that's it.
Even to someone who thinks that time travel was possible, I would tell them that time always moves forward. It must. Even when you travel back in time, your existance would still move forward. You are still experiencing more time that you did before the travel. So I never could understand the argument, "I'll fix it and then I'll never actually go back to fix it becuase it was already fixed, etc...". You were there, and you did something, and your timeline is still moving forward, so what you did will always exist. That would means that the same event would happen twice in your timeline. (The only problem is, this in itself would meant that time is a measures, and the theory would therefore disqualify itself.)
Have you read my journal today?
You know, when science starts sounding like Star Trek, it's time to re-evaluate your assumptions.
I'm all for science in sci-fi, but this sounds like too much fi in the sci... Only Star Trek resorts to the time-travel deus ex machina to make for an interesting show.
Yes, we live in a wonderous and amazing Universe. Yes, technology sufficiently advanced is indistinguishable from magic. But trying to explain a speculative theory with an even more speculative theory is unscientific in the extreme.
Transmeta using alien tech makes for a great joke. Matter traveling backwards thru time?? Please!
-- What you do today will cost you a day of your life.
I can't recall now where I heard it, but I thought it was humorous. It was along the lines of "If time travel were possible, then right now there would be tourists from our future visiting our present."
Well, that's how I remember it, anyways.
BTW, would these "time tourists" be required to wear shorts and loud Hawaiian shirts (well, for the men)?
If this were true, wouldn't the big crunch had to have happened already? I don't doubt that time may be able to go backwards, but I don't believe that it would be able to go backwards before it had finished going forwards. It just doesn't seem to make sense (as if any astrophysics makes sense.)
However, I suppose it could be possible that time is already going backwards (post big crunch) and we are living in a reverse time region.
Of course, then we must assume that the big crunch will happen (has happened?), and as we all know, the currently most accepted theory is that the universe is open and we're not going to have one.
On a side note, I think that all these theorys are becoming way to far out and wacky. It seems like scientist will see something in space that conflicts with their current theorys, then think up some outragous explanation for it. Then, find something that conflicts with their outragous explanation (which has since gained acceptance) and think of something even more wild.
-nick
mistertang@hotmail.com
(i'm not anonymous, my `puter died and i forgot my login/pw)
Even if they figured out that reverse time won't mathematically / quantumly cause the hypothetical annilhation of the universe, there are just too many doors it opens. (now just watch it proved right...) We also can't disregard more conventional theories for dark matter: Black Holes and the possible mass of neutrinos.
With regard to all the discussion of this explaining antimatter:
Antimatter, at least at a surface level is matter that has an opposite spin and charge of its corresponding normal particle... there was nothing in the article to make me think that reverse time has anything to do with it.
Matter and antimatter is anhillated to their relativistic particle energies (E=mc^2 and all) when it hits its a particle of its counter-type (e.g. electron and positron).
All the same, it's an interesting read. Just wish I had the time and the physics bkgd to read the final article when it came out.
__
alt.geek
One might ask the same about birds. What ARE birds? We just don't know.
But really, there are several different arrows of time. It seems the one he's talking about is the thermodynamic arrow of time, in which entropy increases from past to future. Another is the psychological arrow of time. That's the one that where we actually perceive time flowing from past to future.
Now comes the interesting part. Unfortunately, I have to admit I didn't come up with this on my own. I think I saw this in Stephen Hawking's A Brief History of Time, but it's been a while so I can't be sure. But the idea is that these two arrows are always pointing in the same direction.
That being the case, this seems even more flaky. Especially the part where the author mentions that "backwards time" areas could collide with "normal time" areas and make an area of space that didn't have any arrow of time at all.
I'm by no means an expert on this stuff, but from the little I do know, it seems extremely hard to swallow.
If you read the article linked to by the posting, not to far, above your posting you would have had your questions answered without filling database space which makes slashdot run that much slower. Also, the money they most likely spend buying more storage space thanks to irresponsible postings, like yours, could go towards purchasing more important things.
Time is just a variable, like any other dimension. Many subatomic particles move independantly of time. (It's even been proposed that there is only one electron, and it's just bouncing through space-time in ways we don't understand.)
What if the Big Bang and the Big Crunch are the same event? We see them as different because we have a Nutonian concept of time instead of a Quantum one. There is a single creation point, and all mater/antimater/energy radiate from that central point. Subatomic particles have been observed moving backwards in time (Or at least acting like they are), so it's not that crazy an idea. What if existance as we know it is the intersection of this event's various influences?
The cosmic Nirvana may hold countless universes, each with a total energy of zero. What if the entire universie is nothing more than this burst of energy, warping and twisting in space?
Fasinating.....
"Live Free or Die." Don't like it? Then keep out of the USA
I am telling you, my constituents, that if elected I will work my hardest for you and I will stop these confusing 11th dimension conundrums. We dont need to spend any more superstring on crazy dark matter construction projects clogging up our theoretical understanding of the the grand unified algorithm!! Hear me people! If elected I will stop the parks department from hiding 98% percent of OUR universe. If we pay with OUR gravitational fluxing, then WE should be able to exist at the same time! Ladies and gentlemen, vote for me...I want to be your next President of the Space Time Continium.
Where are the keys to my whore?
Everyone wonders why none of these theories work, but that's because they're stupid. It's obvious that our whole perceived 'universe' is simply a computer simulation. Thus, everything we perceive is part of some higher-being's homework assignment and shit. There must be some bug in their code though, as we humans are screwed up and shit. Also, 2+2=5 and Random Rabid Drunken Squirrels will rape you from the fourth dimension. --rrds101@hotmail.com http://www.tams.unt.edu
Well, I think if this is really true, many other things will not work out anymore. There is for example the Special and General Relativity which prohibit such phenomena. There are also Black Holes. How do you make the difference between a Black Hole and "Dark Matter"? So how do yo explain the twin or grandfather paradox?
I think this theory brings up alot more issues then it solves and disproves more then it proves. I would take this discovery with a grain of caution.
Stephan-- Stephan Richter
Please delete this idiot ... this is too off topic!
In the case of the dark matter problem, however, it seems likely that new physics will be required no matter what we do. The reason why is that if there is a whole passel of dark matter lurking in the haloes of galaxies, it can't be made up of baryons (i.e. protons and neutrons). In order for primordial nucleosynthesis to produce the present-day abundances of light elements, there can be no more than about 10% of critical density in baryons; whereas, the amount of dark matter required to explain the observations is around 20%. In fact, all of the types of matter that we know to exist are unsuitable, for one reason or another, as candidates for dark matter. Thus, if the dark matter exists it has to be some sort of "exotic" matter, which is a little troubling.
So, the question is, which sort of new physics that can explain is the least odious. Besides the dark matter, the contenders are modified Newtonian dynamics ("MOND", in essence a small correction to Newtonian gravitation at low densities), and (I guess) this time-reversed theory. Most physicists find exotic matter to be the lesser of the evils. I don't think this paper will change that. The new theory is sufficiently implausible that it will have to make some pretty strong predictions and have them borne out before anyone will (or, IMO, should) take it seriously. Interestingly enough, MOND has gained a small following because it has made some interesting predictions that have been borne out by observations. Unfortunately I can't recall off the top of my head exactly what they were (a speaker mentioned them as a throwaway comment in a talk here a few weeks ago), but they were the sort of predictions on which the standard model is mute; that is, it neither predicts nor forbids the phenomena that were observed. Unfortunately, nobody has been able to come up with a MOND prediction that would be forbidden by the standard model, so as yet the theory is purely speculative.
If I had to weigh in on the matter I'd say that dark matter is still the best game in town. There are several high-energy physics theories extant that predict an assortment of exotic matter, so there is at least some precedent for dark matter, which is more than the alternatives can say. The smart money is usually on the new theories that bear some resemblance to--or, better still, are incremental refinements of--the old theories; although, that's not to say we shouldn't reserve a small wager for the oddball theories; just don't stake the rent money on it.
-r
it requires hamsters dancing across your keyboard
Doesn't this artical say that time is simply a state of matter? We can't really travel backward in time, because as we do, our matter reverts to its earlier state. Therefore, we can't go back in time without reverting to childhood, embryo, twinkle, etc... So the questions of going back in time to kill our mothers or other time travel parodoxes is mute, as whatever we return to has to have previously happened!
I don't have a sig...Do you??
This sounds like something from Calvin and Hobbes.
"I hit you with the CalvinBall!"
"This is a reverse time zone. You haven't hit me yet."
"I hit the opposite pole, so this is actually a forward time zone..."
Heh... I miss that strip.
>>>>>>>>>> Kvort
-Don't mind me, I'm personality-deficient and mentally-impaired.
And perhaps there exists a *darkness* particle - say the "shadowon" - that travels 186,000m/s[rev]...at the opposite end of the speed spectrum, with particles at rest being in the middle at zero.
This *reverse time* stuff is about like arguing the existence of my "shadowon"... it adds nothing to any grand unified theory but more complexity - a monkey wrench that fixes nothing. Unless, of course, we open our minds up to the idea of reverse mass, reverse length and distance, and reverse energy... maybe even the square root of negative numbers. >8]
<---[singularity sig]
"and while we wouldn't see them, we would feel their gravity"
uh... wouldn't this mean that *gravitons* would have to travel faster than *photons*?
Wouldn't that mean also that these time-reversed regions would have their own physical laws that may not necessarily conform to our accepted physical laws. Not only that, but who is to say that we are not in a region of time-reversed space? We could be going in reverse relative to those outside of this region (ie the time-reversed region)
I'd rather sit! -Ian Canino
---
Having briefly read Dr. Schulman's paper from the aforementioned web site, one important aspect seems to be left out of current discussion. He says only "Here I use that framework [whole bunch of references] to show that small interaction does not destroy the arrows [of time]." Later he says: "Can this yield causal paradoxes? [Insert example here] ... In principle such signals could be exchanged and paradoxes avoided as discussed in [a reference]. It is also possible that such an interaction would violate the small coupling assumption. At this stage I draw no conclusion."
It seems to me he is talking about sending a few photons to transmit a signal from the reverse time region to the "normal" time region - and he's saying that may be too much! Much less taking something like a spacecraft or a person from one region to the other. Schulman's work does not say anything about such "larger" interactions.
What is a small interaction? You have to read his paper. He has an interaction parameter in his simulaitions, but I can't figure out what it means in terms of a force or an energy and I can't compare it to, say, the energy of a photon or the mass-energy of a person. Perhaps a person more familiar with Schulman's termonology could comment?
For completeness, the URL of the paper is : http://xxx.lanl.gov/cond-mat/9911101 - for MS win users, you can click on 'other formats' and 'create PDF' to view the paper if you have Acrobat affiliated with your web browser.
a war on terrorism? How can we end a war on a method?
Time is relative to information structures that underly natural phenomena.
Since we are quite strongly aware of an arrow of time, we must be quite close to a major information structure. "The big bang" is as good a name for this information structure as any. But "the big crunch" isn't likely to be a single isolated structure, anymore than the big bang is. This is much like the "earth is the center of the universe" provincialism of early natural philosophy. There could be enormous, yet distant, information structures with localized artifacts near us producing all manner of "weird" effects. Exactly how this might produce additional gravitation is left as an article of faith by the article in The New Scientist but I find it plausible that "dark matter" is simply one of a virtual infinitude of "weird things" to which our eyes are opened once we've accepted the Hamiltonian Revolution the same way we've accepted the Newtonian Revolution.
Lawrence Schulman isn't the child declaring the emperor has no clothes -- he is the taylor who listened to the child.
Hamilton was the child who, without guile, unleashed a truly weird revolution upon physics.
Seastead this.
This sounds a little too much like Calvinball to me.
throws mudball
"The dark matter makes you more massive -- you can't move! I take control of the Calvinball."
"Hah! I use reverse time to make the mudball travel back at you, making you drop the Calvinball in fright!!"
"My superstring ties you down so you can't move!"
Etc...
If it's a simple enough problem that it can be solved mathematically, then what ends up happening?
I've wondered, under the quantum view of matter energy everything is represented by particles. W and Z particles being force carrying particles for the strong force(I think). Theoretical gravitons for gravity and so on. The particles that make up matter(at least baryonic matter) all have anti equivelannts. I'm sure everyone on /. knows when a particle and it's anti come together they are converted to 100% energy. Now if force carrying particles also have anti's, would they make matter when they come together?
Clearly what this physicist should do is file a patent for the "reignition of stellar clouds during massive space-time collapse". Since intellectual property refuses to die, it will likely still apply when the Big Crunch occurs, and he'll file for a federal injunction. The result will be retroactive, and dark matter will cease to bother us in our own time. Hooray.
"If one is really a superior person, the fact is likely to leak out without too much assistance" -- John Andrew Holmes
Isn't there a contradiction in the Theory of Reverse Time?
:-)
:-)
Just like in the place we live in, time and space are tied but we see it going in a "forward" direction. Reverse Time implies that that in such a place, time and space are tied together going in a "backward" direction. The contradiction is that space is never considered! If time is "backwards" then space must also be somehow "backwards." All we know about space and matter says that "space can be empty(devoid of matter) but no less." "Reverse Time" implies that space is less than empty which is a contradiction. Now there maybe a property of space that allows this, and if there is, lets hear it.
Instead, I subscribe to the "Theory of Null Time". Singularities like black holes support this kind of idea. A singularity of space implies that all matter in a given space exists at one point which can only happen if you distort time into a singularity. A singulatiry of time implies that all matter in a given timeline exists in only one instance of time which can only happen if you distort space into a singularity.
The one thing both "Reverse Time" and "Null Time" try to do is explain the existence of "Dark Matter." I think both theories do it well but "Null Time" is a more coherent theory.
Any other theories or ideas on the subject? This kind of theoretical physics has facinated me much like philosophy.
It's a shame you got moderated down; I thought this was damn funny.
"Don't mind me cutting myself on Occam's Razor"
This is ridiculous! Here's why:
Antimatter is theoretically normal matter that 'moves backwards in time', which is also why it's polarized the opposite of normal matter (Anti-positrons have a negative charge, etc). So what you're doing is colliding matter with anti-matter in this above theoretical collision.
Anyone who's watched Star Trek (TNG hopefully, not that Voyager drek, Berman DIE DIE DIE!! Oop, sorry, I digress.), let alone any physicist, knows what occurs here. Antimatter and matter react in a pure energy reaction. There is no matter left, dark or light or normal or anti- or otherwise. "Matter with no time direction"! This guy sounds like a science consultant for Voyager after all.
---
I'm not a real anonymous coward, I just play one on TV.
This is ridiculous! Here's why:
Antimatter is theoretically normal matter that 'moves backwards in time', which is also why it's polarized the opposite of normal matter (Anti-positrons have a negative charge, etc). So what you're doing is colliding matter with anti-matter in this above theoretical collision.
Anyone who's watched Star Trek (TNG hopefully, not that Voyager drek, Berman DIE DIE DIE!! Oop, sorry, I digress.), let alone any physicist, knows what occurs here. Antimatter and matter react in a pure energy reaction. There is no matter left, dark or light or normal or anti- or otherwise. "Matter with no time direction"! This guy sounds like a science consultant for Voyager after all.
---
I'm not a real anonymous coward, I just play one on TV.
Imagine particles that act in every way like "normal" particles, but that are going the opposite direction in time. I suppose this means that they have the opposite reaction to events (after all, time is nothing but causality [causes and their effects], right?).
Such particles wouldn't interact very well with "normal" particles for obvious reasons, but would interact very well with each other. So, you'd get anti-time atoms and molecules and stars and galaxies completely seperate from our own.
I was also confused for a moment when i thought, "If these guys are going backwards, then they must be created in the big crunch instead." Then i realized that they aren't actually going backwards, just having opposite reactions to the same things, which would make them appear in every way to be going in the opposite direction. You just have to look at it as cause-and-effect, not the flow of time. Time isn't flowing one way or the other. Stuff just affects other stuff.
In conclusion, this would make it impossible to jump into an "anti-time" zone and go back in time. But OTOH, some of this anti-time matter would be pretty fun to play with. Imagine the implications of having something as simple as a ball made out of it.
Then, if your head is still intact, try designing something mechanical using it. If you come up with anything cool, tell me about it. :)
We observe the real universe to have its origin in a state of extraordinarily low entropy -- immediately after the Big Bang, matter/energy was uniformly distributed throughout its entire volume to the level of one part in 100,000 (the smoothness of the Cosmic Microwave Background radiation, as measured by the COBE satellite). Thermodynamically speaking, then, there was only one way for the universe to go -- towards gravitational clumping, collapse, the formation of stars and galaxies, and other sources of entropy (like us). This establishes the thermodynamic arrow of time for the universe.
The actual existence of regions with opposite arrows of time depends, in Schulman's paper, on the ending of the universe in a Big Crunch. But there are two problems with this.
- All existing astronomical evidence points to a universe that will expand indefinitely (and may even be accelerating). Even with Dark Matter, there's just not enough mass around to hold it back.
- Even if the universe were to end in a Big Crunch, there is no reason to think this would be a state of extremely low entropy.
Thus even if the paper is correct it is not relevant, in an astronomical sense.I'll end by pointing out that there are several less dramatic solutions to the "Dark Matter" problem -- now that we know neutrinos have mass, for example, it becomes pretty easy to imagine that there are other more-massive weakly interacting particles out there, the WIMPs, and that these could easily have evaded our detection efforts to date (good reason to continue upgrading the experiments!). A slightly more daring alternative postulates the existence of "mirror matter" which interacts even more weakly with the ordinary stuff that we're made of. Neither of these types of matter, nor for that matter antimatter, should be thought of as travelling backwards in time.
Other articles from the current New Scientist:
Sex is good for athletes before the game
An ice age is coming to Europe
Bringing dinosaurs back to life
The Pill may lead to gum disease
Stress may protect your from loud noises.
I would not consider this publication a valid source for scientific news. In addition, they are publishing an article that has not been subjected to peer review. "Schulman's calculations will appear in a forthcoming issue of Physical Review Letters."
If anyone can find collaborating evidence, I would like to see.
My 2cints
Sig-"Out beyond fields of wrongdoing and rightdoing, there is a field. I will meet you there." Jelaluddin Rumi
Not as humorous as you may think.
Actually, you are free to visit other spacetimes, regardless of your spacetime origin, as long as a)you have the cash, and b)you agree not to remove your (dark matter-based) camouflauge. The Intergalactic Travel Agency will not hesitate to enforce these policies using Schulman's "opposite thermodynamic arrows of time." If you qualify for the trip, you probably already received the brochure.
This message meets the requirements of the Intergalactic Travel Agency code #1999a12.
If any of you had read the Red Dwarf books(the series depicted it differently), you would know an implication of this: The main characters dies of old age, the genius computer sends him to a reverse time dimension(not another part of our dimension), and he comes out 25 years old. I can see commercially-run operations sending thousands of wealthy old people to these regions already!
Slartibartfast:"Is that your robot?"
Marvin:"No, I'm mine."
Virtually all physics papers are published online before they appear in printed journals. Physicists invented the web, remember?
I closed the anchor tag properly in the HTML I submitted, but somehow it was removed.
As a time traveller, using current theories, would need a spaceship to even enter these regions in the first place.
Have you ever thought about taking sculpture lessons?
Ahhh.... another segfault (L)user joining our midst... it's just been too hard for you since Segfault's turned off their comment board, huh? No more petrified girls and clits... grow up, you're fucking pathetic. Is this harry@angryanddrunken.com? You need to grow up, how old are you?
People like to think of going back in time, mainly because of the psychologically tragic reality of 20/20 hindsight.
The problem is the complexity a backwards traversable universe creates.
For example, if one can travel back to 1950, that implies that, somewhere, somehow embedded in either the fabric of the unvierse or in the structure of subatomic particles is the exact memory of where and when everything and everyone was. Perhaps an infinitely growing thread(imagine a pencil leaving a trail as it moves over a paper...of course, some small chunk of the pencil is removed with each motion), or perhaps some kind of structural memory, but somewhere, the State Of What Was has to be preserved.
Sounds rather deterministic, in a universe that seems to have blurriness built into its very design.
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
But isn't the universe that is reborn after the big crunch going to be exactly the same as ours and aren't we merely tied to the molecules of our brains, forever repeating our lives in the same point in time at the same place every time the universe restarts?
See:
Opposite thermodynamic arrows of time
for the abstract of this paper about to be published. More articles scheduled for the same issue are available here.
Energy: time to change the picture.
So this means that patents and copyrights laws are relatively useless. At least at a Universum dimension...
Ooooooh. I see the future claimers
Copyright 1999 Ektanoor All rights reserved for Past, Present and Future.
Being a sci-fi addicted adolescent, I asked him about time travel, and could he explain what the current thoughts about it were.
His answer was so beautifully simple, and it went something like this:
- "You know that we can create particles in an accelerator with different-than-normal charges, right? (Right.) Take the positron, for example: It's an electron with a positive charge, just the opposite of what a 'normal' naturally-occuring particle would have. We can create (small) atoms that have different charges, and manipulate their electrical potential as we see fit. With me so far? Good.
With that thought, he left me to fry my mind considering the possibilities. Stars running backward are certainly one possibility, but I think that entropy will continue to be the order of the day until the 'Big Crunch'. Even in a contracting universe, stars will shine, coffee will be spilled, and cups will be broken, all until everything is crushed out of existance. I seriously doubt that there will ever be a time when our lives look like a film run in reverse.Now, we theorize that the time properties of a particle behave in very much the same manner as the electrical charges. The catch is, if a particle has a different time charge than the matter that makes up our reality (and our detection equipment!), we won't be able to observe it, just the affect it has on other matter as it makes it's journey through time."
Remember the wizard Merlin in the King Arthur / Camelot tales? He lived his life backwards, and thus could remember what we would consider the future! That was cool.
"...America's great minds of today, teaching America's great minds of tomorrow. Poor bastards." -- A Beautiful Min
So what does this do to entropy? Seems to me like, since the total entropy of the universe must always increase with time (and, far as I can tell, this is one of the only things that is completely dependent on the flow of time), areas of reverse time would decrease in entropy.
Is it just me, or does that throw the Second Law of Thermodynamics out the window?
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.
-Albert Einstein
What about light from stars transmitted through these reverse-time regions? Will it go backwards? (ie. reflect back towards the source)
In that case, we would be seeing large reflective regions of space in the night sky, right?
I wish I had a nickel for every time someone said "Information wants to be free".
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
i agree.. and slashdot encourages humor!
-mg.
wow, i just spend like 5 minutes trying to use babblefish to translate that... god.
David Brin wrote a similar story as well, wherein the hero could only sucessfully build a time machine that had the "back-in-time" button disabled.
Nothing for 6-digit uids?
Like almost all scientific articles, it is a piece of fiction that might be interesting to some subset of people. It might even contain elements of the mythical TRUTH. Barring an assumption that I choose not to make right now (making me unpopular at times), we will never know.
This particular piece of fiction makes sense in a few limited areas, and meshes with some other not too widely accepted explanations of the modern scientific religion. It touches on one of the core beliefs of the science saying that there is a concept called time that we percieve to move in one direction. Many followers of science believe or fantacize that this perceptual illusion is permeable, so stories will continue to be rise about how time is reversable or non-existant. This is because people want that to be true.
Why do I refer to science as though it were a religion? Because it is.
If you deny the fundamental set of assumptions that the scientific method is based on, it is complete fiction. One person makes up a story and meshes it with a story that already existed. A few threads of the new story doesn't mesh well with the old story, so a few details of the old story are declared wrong and a few details of the new story are plucked out and suddenly the two seem to fit. As "time" progresses, more and more people include the new story in their personal views of how the world works and move on until new stories are added and change it again.
If you don't like the theory, fine. Don't adopt it as a part of your personal doctrine of science. 90% of the population in the United States doesn't seem to actually know how science works, so it really shouldn't matter to you unless you are a practicing scientist in that field. If you are, then you will want to look at it as a potential doctrinal change. (Yes, I made up that statistic, based on extrapolation from my own experiences.)
All of that said, no, I don't believe this theory out of hand. Yes, I believe in science (as a philosophy and as a State religion). No, this is not a deliberate troll. I thought I would throw in a perspective that most people don't seem to have.
B. Elgin
"Read at your own risk; feel free to ignore."
B. Elgin
B. Elgin
"Read at your own risk; feel free to ignore."
Hello:
I remember watching an episode of NOVA about time travel on PBS a bit ago. Stephen Hawking said on that program that time travel isn't really probable. He also said if it were possible: "how come there haven't been any time traveling vacationers from the future?" An interesting hyposthesis!
Rajiv Varma
I'm very under impressed with this article. *Most* of the laws of physics are symmetric with time, the exceptions being strange things like kayons. That a particle is moving twards more order (which the author implies) doesn't mean that it didn't have a past or doesn't have to play by the rules of the rest of mater in the universe. People who think about dark matter are worried about what type of stuff it is (weakly interacting massive particle [wimps], nutrinos, gas clouds, etc). What that stuff may be doing in our future (its past?) doesn't solve the basic question of what it is.
We already know what matter moving backwards in time looks like, and we've created it in labs. It's called antimatter.
At the time I was posting there were 0 (zero) replies to the article. Apparently the script that generates the page had not updated yet.
Some time significantly AFTER I posted, someone finally posted a link to the preprint of the paper - which is what I was asking for.
The reason I had to ask for info is that the slashdot peeps didn't put up a link to any substance-filled info, like a preprint.
Seriously, think before you loose the flames - otherwise you tend to make an idiot of yourself.
Boors like you is the reason I've grown to be highly critical of slashdot.
they're finally catching on... about ten years ago, came to the conclusion that casuality runs "backwards" through time -- but its really us that are going backwards through time. what we call reverse-time is actually forwards time. therefore the statement "the cause changes the effect" is incorrect; it would be better to say, "the effect changes the cause!". :-) regards - http://home.earthlink.net/~johnrpenner/
WE WANT THE CURRENT VERSION OF THE SLASHDOT SOURCE CODE!!!
--- Just focus on scrapping Windows, 'kay?
This in not BS in B.S. but in bullshiizzzz. Stephen Hawking had writen something about these damn reverse time sequences not being possible. One they are not predicted in special realitivity because theoretically the dark matter would need a velocity > C. Which under current large scale physics is not possible. Or the only other possible theoretical explaination would be that all this matter is in a constant state of QUANTUM FLUX or a eternal Quantum Jump. In that its energy could be DETECTED (possible radiation emiter) But the sources definate position or veloctiy could never be detected. HENCE it would give you a very large headache try to do the math to explain DARK MATTER.
test
"For those interested it is the easiest way of getting time travel. One day you come home and find all the plans for a time machine - you build it and then return to leave the plans for yourself (the exact pieces of paper)"
Ok, first of all, I believe that this can't happen, because, quite frankly, knowledge can't create knowledge. You can't say that we learned time travel because our future selves told how to do it. How did they learn it? Let's say that they discovered it, say around 2500, and then went back in time and gave the blueprints to us, in 1999. This would certainly change what is the present for the time travelers (2500), since they had time travel capabilities since 1999, and didn't need to discover it in 2500. By giving us the blueprints, they affected their timeline, begining in 1999, all the way up to their present (2500).
But that's one possibility. If there is only 1 universe (no parallel universes), and our changing of the past affects the future, then we have serious problems. Many, many paradoxs can arise, such as the going-back-in-time-and-shooting-myself paradox that everyone loves.
Richard Feynman addressed this issue once by implying that one simply cannot change the past. The example he gives is of a time travler (or chrononaut? is that a word) who goes back 5 years in time and attemps to shoot her past self. However, she misses the heart, and the bullet hits her younger self in the shoulder. Why did she miss? Because her aim was affected by her shoulder - the time traveler was shot in the shoulder 5 years ago.
The other option is that there are parallel universes, and that possibly they are spawned for every possible action in the universe at any given time. If this were the case, and you went back in time and shot yourself, you simply would be dead in THAT universe. You're still alive and well in your own, even when you returned to your own time.
Just one more issue to address - one may say, "Hey, if you go back in time, say to when you were 10 (and you are 20), then aren't there two of you in the same universe? If you met your past self, wouldn't you faint or destroy the universe like in Back to the Future 2?" Well, i'd have to say no, you probably'd no neither. I don't think anything would happen, except for the fact that the present you would be staring into a 10 year young mirror. Also, keep in mind, you can't be in 2 places at once. Even as you are there, staring at your younger self, you are NOT where should should be (in the future). You are present in the past, yet missing in the future, even for only a split second, so it evens out. And remember, time is all relative (I hate time). So don't worry that your extra mass (that is in the universe at the time you're visiting your younger self) is going to cause a sudden cosmic crunch :-)
Btw, the above assuptions (the 20 year-old visiting his 10 year-old self) are made with the assumption that we're dealing with 1 universe here, as opposed to parallel universes.
/.
This interpretation does not need observers (as in the standard Copenhagen interpretation), and thus do not suffer from the problem of needing infinite observers (in order to collapse the observer, you need an observer, who need an observer, who ...).
The only concession it makes is that some particles (moving at the speed of light, and thus not experiencing time) need to move backwards in time. This is, in my opinion, a nice tradeoff.
Eivind.
Doubting the existence of evolution is like doubting the existence of China: It just shows that you're uninformed.
Bwahahahahaha! I got the first post!
-russ
Don't piss off The Angry Economist