Slashdot is powered by your submissions, so send in your scoop

 



Forgot your password?
typodupeerror
Note: You can take 10% off all Slashdot Deals with coupon code "slashdot10off." ×

Comment Important Takeaway (Score 3, Informative) 162

This just demonstrates one very valuable fact for any hopeful cloud OS wannabe: If your desktop environment sucks 'because you're a cloud OS', then you won't be a Cloud OS.

If the admin can't get familiar with your OS on their personal desktop, they are not going to think of using you in a mission critical place. The best server OS has to be a good personal OS too or it will never become popular enough. RHEL started off as just RedHat, one of the better distributions for Linux. 'EL' was just a backend change to the same comfortable front end, just as Windows Server is familiar for those who use Windows as their primary desktop.

Comment Re:Inaccurate Summary (Score 1) 138

I explained, backed with math and citations, the relativistic effects on communication between the Earth and a ship; the entire timeline of the journey as perceived by both sides.

The math for the Doppler effect combined with time dilation was demonstrated two ways, both by examining the time experienced by both sides (and working out the speed of the communication that would match that time) as well as examining the actual doppler effect separated out from the time dilation. The math, in both situations, works out the same... communications arrive at 1/3 speed while the ship flies away, and arrive at 3x speed while the ship flies back for a ship traveling at 0.8c relative to the Earth.

Rather than assert your correctness, would you kindly do the math and demonstrate why I am wrong? You obviously studied. Perhaps you are even a scientist in another field. But I believe you would learn something if you tried to actually do the math and work through the problem completely.

Relativity is a fascinating subject, but it's not magic. It doesn't suspend all other physics when reletavistic effects come into play. It's more a mild warping of normal physics that gets more pronounced the faster you go. But even at 0.9999c, all that normal physics is still there, and it still occurs the way it always does, you just have to add in one new term to the equation.

Comment Re:Of course it never gets past the event horizon. (Score 1) 167

I like this theory. It's clear, consistent with previous observations, and provides a clear explanation. But I don't understand one thing.... what happens when the Black hole expands?

This great explanation you gave only works after the black hole is created, and is now slowly losing mass via Hawking radiation. What happens to an observer when they fall in and the radius of the event horizon increases to a point beyond where they got 'stuck' in the stopped time of the horizon?

Comment Re:Inaccurate Summary (Score 1) 138

I'm sorry, but you are incorrect.

Perhaps you would like to explain how 8 years of communications reach the ship as it is 'changing frames' on the star 4 light years away? What you are describing requires information to travel at faster than light speeds. Can you explain when the doppler effect stops working as things get faster? Does the doppler effect stop working at 0.01c? At 0.1c? At 0.5c? Can you provide a source?

Here is what happened to you, perhaps years ago. You read and partly understood the frequently cited explanation about ships passing each other. The situation described in those explanations exists only for a moment as the ships motions are parallel. But as they are approaching each other, their transmissions are dopplered to arrive faster, and as they leave each other, they are dopplered to arrive slower. That's the entire point behind 'redshifting'. By your explanation light in behind and in front would be red shifted (time slowed down). That's what redshifting and blueshifting are... the change in the frequency of light.

And what is frequency? It's how many waves arrive per second. If I transmit 1 million waves of red light, and you receive 1 million waves blueshifted blue light, it takes less time to arrive because the frequency of blue light is higher... if I encode information in those 1 million waves, you receive that information faster when it arrives blueshifted. It doesn't matter if it's blueshifted a little or a lot, or if I'm undergoing relativistic dilation or not... it still arrives faster, and thus the perceived rate of time change is higher.

Also, think about this. The ship is approaching at 0.8c. If there were no relativistic effects then it would perceive the transmissions arriving at 180% normal speed, or 1.8x normal. But because of the time dilation on the ship (60% normal) that 180% becomes 300% (1.8 doppler / 0.6 relativistic = 3.0x perceived) perceived reception rate of the transmission. Similarly as they fly away from each other, without relativity transmissions would arrive at 1/5th speed (0.20 doppler), but because the ship's relativistic dilation is 60%, that 20% becomes 33% (0.2 doppler / 0.6 relativistic = 0.333 perceived).

So relativistic effects occur, but that doesn't mean doppler effects don't.

Comment Re:Inaccurate Summary (Score 1) 138

Why this works requires some use of the time dilation equation. Let's work with a relatively basic speed: 0.8c. That's the speed where time appears to be about 60% as fast (in both frames) when two ships are being compared to each other. Now let us imagine a ship flying away from the earth to a nearby star and back. In fact, let's steal the example given in this explanation of the Twin Paradox on Wikipedia. You should go read that first, because I'm not going to repeat what it says here.

There are two parts to that trip... the journey out, and the journey back. Let's examine each side's perception of the the other on the way out and the way back.

  • From the point of view of earth, the ship takes 5 years to reach the star. After five years have passed however, even though we know the ship has probably arrived we are still receiving transmissions from back when the ship was only partway there (the transmissions from when it arrived won't reach us for, obviously, 5 more years). In fact, after five years we are just receiving the transmissions from when the ship was halfway there, 2.5 years out. And because of the time dilation, the ship appears to be aging at 60%, so we have only gotten 1.67 years worth of communications (the signals reaching us have a timestamp of 1.67 years from the start). So in 5 years, we have gotten 5/3 = 1 2/3 years of data. Time seems to be passing at 1/3 the rate on the ship.
  • Now let's step up the weirdness. From the point of view of the ship, it's going to take 3 years to go 2.6 light years (Lorenze contraction). When it looks back after reaching the star, it sees the sun as it was 4 years ago (because it's 4 light years away). So for the '3 year journey' that the ship perceived, it only received 1 year's worth of communication. It is now 4 light years away and receiving messages (light) that have a timestamp of just one year after the start of the journey. To the ship, it was the Earth that was operating at 1/3 speed!

Ok, so we've just demonstrated that as objects fly away from each they both see the other operating slowly... as if the objects 'behind them' were moving in slow motion. What about when they start moving toward each other?

  • Back to the Earth's reference point. Even though the ship has already started coming back at the 5 year point, the Earth won't get those transmissions for another few years. Remember that the ship traveled 4 light years, taking 5 years to do it from the view of Earth. So we won't get the clock from the turn-around until the nine year mark. At that point (because of the 1/3 relative time dilation) the clock on the ship just hit three years. The ship is going to have three years of transmissions as it returns, and by the time it returns there will be no delay due to distance... what's that mean? It means that the blue shifted return transmissions provide 3 years of updates in the one remaining year of the trip. In other words, as the ship approaches time seems to have accelerated to 3x normal!
  • Finally, to complete it all, let's go back to the ship at the star when it turns around to return. It has traveled for three years and is receiving transmissions from Earth that have a timestamp just one year after it left. Now it's going to fly back to Earth. At the end of that trip Earth will have aged 10 years... so how much data arrives in that 3 year trip back? 9 years. While returning to Earth, the ship receives 9 years of transmissions over what seems like 3 years of travel time.

So the earth sees the ship move at 1/3rd speed for 9 years, and 3x speed for 1 year, for a total time gone of 10 years, and a total time on the timestamps from the ship of 6 years.

The ship sees the Earth move at 1/3rd speed for 3 years, and 3x speed for 3 years, for a total travel time of 6 years, while the total number of years that the timestamps on the transmissions from Earth showed... 10 years.

Relativity is crazy, but the math makes sense. The important takeaway is that objects approaching each other see both sides as moving faster. That's what the doppler effect is. This is just extreme doppler on doppler action.

Comment Inaccurate Summary (Score 4, Informative) 138

A better way to put it is that when you are travelling nearly the speed of light, if you look behind you at the place you are heading away from time seems to stand still for it; the light from your old hometown is redshifted. But light that's coming in from in front of you (and thus, the perceived rate of time) is way higher. Time seems to be moving a hundred times faster than normal as you look at an oncoming blueshifted star. Then, the star passes you and all of a sudden it slows down... from your point of view.

So from the point of view of the fast moving observer, time is sped up in front of them, and nearly frozen behind. As they travel they pass galaxies that are growing old very fast, but leave behind them a frozen universe, that is changing imperceptibly slowly.

When they stop... they are not 'surprised' that the universe is old. They watched it grow old in front of them. Nor are they surprised that their home, now billions of light years away, has not changed much (it looks 'young') because behind them time seemed to stop. The perceived universe makes sense from the viewpoint of the traveler. Point being that there is no paradox. What happens to the fast moving universe would look really weird from inside (because of the starbow effect), but they would be used to it. You know... assuming they survived the X-Ray energy sleeting through them from impact with intergalactic matter.

Comment Note 4 (Score 2) 208

The Samsung Note 4 is still a high end phone (until the Note 5 comes out, only the iPhone 6 hase more performance), and a removable back. You can add a monster aftermarket battery on to it. It's likely to drop in price (it's already started) as the Note 5 comes out.

There is no faster phone, that I am aware of, with a replaceable battery.

Comment Like All Defenses... (Score 4, Interesting) 110

... this will last only until the facial recognition algorithm is trained to ignore it. If it won't fool a human, it won't fool an algorithm for long. Better fixes are ones that exploit the weaknesses of the sensors rather than attacking the algorithm. The other example, cited right in TFA, uses a more effective long term strategy of hampering the sensors.

Upgrading the algorithm? Cheap, and only needs to be done once. Upgrading every sensor to filter IR? Not impossible, but much more expensive and thus likely to be skipped by businesses.

Comment Why a Language? (Score 2) 30

This seems to be an appropriate use of a DSL, not a new programming language. Just add some constructs to an existing language (Ruby and Lisp are particularly good at making seamless DSLs) embodying the new concepts. A language is a silly way to deal with this... instead, choose a language that supports the features you need and add the concepts to it.

In this case, a language like Erlang or Go might be good choices, both designed for robust, concurrent, and distributed processing. Add in a library to either (or both) that embodies the concept of neighbors and swarms and you get multiple wins: an immediate pool of programmers who already know the language, far fewer bugs in the core language, better performance, dev environments, compilers... a long list of wins right off the start.

There are sometimes good reasons to create a new language. But this is not one of them, in my opinion.

Comment It's Not Complicated (Score 1) 82

If the data or encryption key is out of your possession, you must assume it is public. If you want to secure your data, it must be encrypted before it leaves your computer. And if you want to trust your computer, you can't use a proprietary OS.

Most people don't need that level of security... some convenience is worth the likely loss of privacy (to a point). I'm not going to worry about getting my cousin to use PGP in order to email about our family reunion. But if you are concerned about privacy, you have either already eliminated cloud services from your daily workflow or you are an idiot.

"Sometimes insanity is the only alternative" -- button at a Science Fiction convention.

Working...