Become a fan of Slashdot on Facebook


Forgot your password?

Comment: Re:Kludgy Mess Requires Kludgier Foundation (Score 1) 34

by lgw (#49552163) Attached to: Mystery of the Coldest Spot In the CMB Solved

Inflation was cooked up to explain most of that after the fact, though, so it's unsurprising that it does. The fundamental problem with inflation is that too much is tunable. Penrose's cyclic cosmology explains all the same stuff, and at least has the decency to make some bizarre (and very likely false) predictions outside of the early universe.

Theories of the very early universe that require new fields that there's a way to detect today are interesting. Certainly there are ideas to explain dark energy as an extension of inflation that fit that bill. But theories that propose a bunch of cool new physics that all conveniently vanished early on are a bit sketchy, at least until we can somehow make an equivalent of WMAP for the neutrino background radiation, and observe the very early universe directly. I hope I live to see that!

Comment: Re:me dumb (Score 1) 148

by lgw (#49552095) Attached to: Wormholes Untangle a Black Hole Paradox

If you can avoid traveling in normal space-time, then you've just potentially solved the problem entirely.

That doesn't help in the least. It doesn't matter how you travel: two events, separated in space, that happen "at the same time" in my frame of reference don't do so in another. If I depart A and arrive at B "instantly" in some reference frame, then I have travelled backwards in time from another. There's no getting around that: we live in a relativistic universe.

Comment: Re: me dumb (Score 1) 148

by lgw (#49552071) Attached to: Wormholes Untangle a Black Hole Paradox

You seem to think the QM guys cooked up this really weird story while particularly high one night, then went looking for a way to make it fit the universe. It's the observations themselves that bring the weirdness. Sure, the universe at these scales far from human experience doesn't fit with our intuitions, but that shouldn't surprise, as our intuitions are based entirely on human experience. Sure the math is intricate, far from simple or elegant, but there's no actual reason to believe the universe is simple and elegant, other than it would be nice if it were so.

Is this all some complex expression of some simpler, underlying truth that we just haven't found yet? Certainly everyone working in the field hopes so! But the horrible, crufty Standard Model just keeps making accurate predictions, and all the clever ideas of physicists to create a simpler underlying model that could explain everything we measure keep failing to do so.

Comment: Re:me dumb (Score 1) 148

by lgw (#49551993) Attached to: Wormholes Untangle a Black Hole Paradox

It seems like you're missing a key concept here: "simultaneous" depends on reference frame. If two events separated in space, A and B, happen at the same time in my reference frame, there's a reference frame in which A happens before B, and a reference frame in which B happens before A. There's no one true order of events.

This causes no paradoxes in relativity, precisely because you can't send information, or cause an action, faster than the speed of light. The propagation delay between A and B ensures cause precedes effect in every reference frame, and the order of events can't quite shift enough to overcome that propagation delay.

But moving FTL breaks all that. If I move "instantly" in my reference frame, then there's a frame in which I move back in time, and a frame in which I jump forward in time. I don't move back in time in my own reference frame, sure, but I really do in another. And if you're moving quickly relative to me, I can use that to relay a message from you to your past self - either by a series of accelerations between the frames, or by using a friend in your reference frame who can teleport as well.

If I want to visit my own past self, I would need to teleport some significant distance, accelerate up to relativistic speed, again teleport a significant distance, then accelerate again to match location and speed with my former self - elaborate, but possible. Or, if I could travel a great distance, say 1 billion light years, "instantly", then I don't need much acceleration at all, just the difference in velocity the Earth achieves in 6 months as it makes half an orbit would do it.

Comment: Re:me dumb (Score 1) 148

by lgw (#49548161) Attached to: Wormholes Untangle a Black Hole Paradox

Well, there are several "kinds" of wormholes. In one, the distance really is 3 ticks, in every way that matters, and the fact that there's also a 10-tick path (which used to be the shortest path before the wormhole) means nothing, as there are an infinity of circuitous paths. But that's not this kind of wormhole.


To see the problem, imagine 2 wormholes, A and B, each with widely separated endpoints. In my reference frame, the endpoints A1 and A2 are stationary - I'm standing by A1 and can send a message instantly to A2. The endpoints B1 and B2 are stationary relative to one another, but are moving close to c relative to A. In B's reference frame, my message goes back in time.

If my message gets relayed A1-A2-B2-B1 just as the endpoints pass, I'll get it before I send it. In my reference frame, A1-A2 is instant, but B2-B1 goes back in time. In B's reference frame, A1-A2 goes back in time, and B2-B1 is instant. Either way, it's a causal mess.

A simpler example: you can get a straightforward time machine simply by accelerating one end of a wormhole up to relativistic speed for a few years, and then bringing it back, parking it at rest near the other end. Like the twin who visits a distant star and returns, one end will be "younger" than the other. Now the wormhole moves you back (or forward) in time by a few years when you traverse it.

Comment: Re:me dumb (Score 2) 148

by lgw (#49547911) Attached to: Wormholes Untangle a Black Hole Paradox

OK, I tried to read your first sentence 3 times, and I still can't parse it, so I'm not sure what you're saying. Naturally, slower-than-light state transfer doesn't introduce paradox. FTL state transfer does allow inversion of cause and effect - the clear examples of this involve two pairs of wormholes, moving quickly relative to one another, which allows you go send a signal out through one pair and back through the other, and get the signal before you sent it.

Comment: Re:me dumb (Score 2) 148

by lgw (#49547767) Attached to: Wormholes Untangle a Black Hole Paradox

It's early days for this idea. This is theoretical physics, so it's usual for it to take a while for someone to come up with a proper experiment. Compelling, convincing experiments that have demonstrated the Bell inequalities (the EPR paradox) really started in 1998, decades after the theory was broadly accepted.

This paper was more about black holes than quantum entanglement, and that stuff is harder still to test. It's the implications for QM that are really the exciting bit. It may well be that this is just a different explanation for the same phenomena, and so will remain "just theory" until we find some way to observe black holes closely. But if in fact it works out that this would be a modification to the mechanics of entanglement, someone will devise an experiment for it, as entanglement is still an area of interest for the experimental physicists.

Comment: Re:But I can still get piss drunk at the pub, righ (Score 1) 110

. I suppose you think we all still wear bowler hats and say 'what ho Jeeves'?

I met someone in a bowler hat just last week. He was also wearing a kilt. And a bright purple shirt. Picture that combination for a moment.

They key to unlocking the fashion mystery? Jury duty. Sure enough, he didn't get picked. Clearly he'd been living here for quite some time (long enough to be a citizen), so I can't hold him as representative of all the UK - I'm sure you don't all wear bright purple shirts.

Comment: Re:me dumb (Score 5, Informative) 148

by lgw (#49546839) Attached to: Wormholes Untangle a Black Hole Paradox

I can't explain the mathematics Leonardo is using (best nickname ever), but I can explain the basic idea.

Wormholes can connect two arbitrary points in spacetime - this allows FTL travel, but that means time travel, with raises all sorts of paradoxes. The current understanding of this style (ER bridge) of wormhole is that they're inherently unstable - the math allows them to form, but they'd collapse as soon as anything interacted with them.

Quantum entanglement says that two entangled particles have this oddball relationship that one somehow knows that the other has bean "measured" (any real interaction between two particles is a "measurement" in QM, it's not some special thing), in a way that's seemingly faster than light, but can't be used to send information.

These two ideas dovetail nicely - if quantum entanglement means the two particles are connected by a wormhole, which collapses the moment either is "measured" (i.e., any time they interact with anything new), then you have a way for that communication to happen FTL, an then the two particles are disconnected and no longer have any special relationship. You don't get time travel paradoxes, because it's the nature of entanglement that you can't use it to send data FTL even though the effect is FTL.

It sounds neat, but that almost counts against you in QM. The key is whether the math works. Exciting if true, however.

Comment: Re:Unity next (Score 1) 452

by lgw (#49546715) Attached to: Ubuntu 15.04 Released, First Version To Feature systemd

I use both Ubuntu and Red Hat daily at work. I really don't like the current Ubuntu desktop - it seems inspired by good ideas, but it doesn't deliver them. Red Hat's very old school desktop is straightforward and intuitive, if limited and ugly. But I'll take limited and ugly and can get work done over the alternative! (This is also my argument against systemd, of course).

I haven't seen XFCE in forever, but I remember it being really fast anf lightweight. XFCE with a taskbar would be my dream.

Comment: Re:Amazon has really been a stealth company (Score 1) 76

by lgw (#49546543) Attached to: Amazon's Profits Are Floating On a Cloud (Computing)

. I think there are very few companies, including profitable ones like Microsoft, that have that luxury.

I think any company can do the same, as long as they convince their large investors they have some sort of long-term plan that justifies it. While stock prices are batted about by people chasing quarterly results, those speculators aren't going to evict the board of directors, they'll just sell and move on. It's the large, long-term investors, the pension funds and mutual funds and so on, who will make the effort to cut the head off a company if they think the current board/CEO are fools. As long as they believe your plan will work, you can take short-term losses if you have the cashflow, or can borrow.

Microsoft is in a unique position that that have an insane amount of cash, can run at a loss for a decade without going under, and the long-term investors just cut the head off the company in favor of a long-term plan. They really have no excuse at all here.

Comment: Re:And it's gonna rain (Score 1) 76

by lgw (#49546483) Attached to: Amazon's Profits Are Floating On a Cloud (Computing)

Isn't AWS used for more than cloud storage and computing? It's also used for simple web hosting. Did they subtract the revenue from website hosting from that $1.5B figure.

AWS includes far more services than I've ever heard of. "Cloud computing" is EC2, which you could use for web hosting once you grow large enough to need a full VM (or 1000). I'm sure theyalso have some web hosting product somewhere for personal-sized sites too. All of that, plus the storage and so on - everything "cloud" - is AWS (I know of their queueing service and their load balancer service, but I've only looked for the obvious stuff).

The fact that it's collectively profitable despite the price wars should be a real wake-up call for anyone using "cloud" as a loss leader.

Comment: Re:Dead until 2016 or 2020 anyway (Score 1) 99

by lgw (#49546347) Attached to: Bloomberg Report Suggests Comcast & Time Warner Merger Dead

You do realize the real contribution from these companies are many millions, right? Except to the Clinton "charity" and a $300k speaker fees for Hillary, instead of on the books? (And it's not like the Clintons are especially corrupt here, compared to the rest, though they're more brazen than most about it.)

Any given program will expand to fill available memory.