The invariance of a particular speed in all inertial frames.
This you can use as an experimentally verified starting point if you go with the mainstream interpretation of Michelson-Morley. All the rest follows very easily by just drawing a Minkowski diagram. No need to go through the whole clock syncing rigmarole. The LT are immediately accessible.
But again, you don't need that shortcut if you take the much more general approach outlined in the 1976 paper. The latter is certainly the way I'd introduce it to a student.
Relativity is based on the synchronization of clocks
This is an unfortunate and very common misconception. Most textbooks still follow the clock synchronization route to SR because that is how Einstein derived it in the first place. But as with most theories the oldest presentation and approach is usually not the best or most elegant one.
To derive SR all you need is some basic assumptions about space and time (homogeneity, isotropy) and one extra bit that you don't find in classical physics: The invariance of a particular speed in all inertial frames.
A nice presentation how this leads to SR can be found in this rather remarkable textbook that otherwise mostly deals with QM (Disclaimer: I am not the author nor do I know him or benefit otherwise from an endorsement).
Yet, there is even a more general approach to SR that can be taught on an introductory level. Here the assumption of an invariant speed is not required either and substituted by group law first principles that feel just as intuitively right as the assumption that space is homogeneous and isotrope. Namely we require that our transformations must always have an inverse one and a composition of them must result in the same class of transformations. Out pops SR.
This paper is really a thing of beauty. Professor who still teaches SR starting with clock synchronization should be punished to copy it by hand until their fingers bleed.
The sad thing is it has already been published 1976!
But to this day SR is still taught following Einstein's original convoluted path. Of course with the predictable results.
In quantum physics we are already accustomed to situations were the measurement, i.e. act of observation, can determine a particular physical outcome.
If superluminal neutrinos are real we may have a similar situation. I.e. they can only be measured as faster than light in a reference frame if no measurement is attempted in another frame that'll break causality.
They imply that light speed is an invariant under coordinate transformation i.e. the implicitly contain the Lorentz transformations. The explicit experimental confirmation for this invariance of c is the MichelsonMorley experiment..
Quantum computing is adiabatic computing. I.e. fully reversible without entropy increase. Hence a complex quantum computation is theoretically not an my more energy intensive then a simple one. Entropy only increases at the end when the final measurement is performed.
What makes the process tricky is keeping quantum coherence over the length of the algorithm.
What stood out to me was that they found about 5% Denisovan DNA. The latter being an early human that evolved independently from Homo erectus. This genome can also be found in some other Asian aboriginal populations but not modern day dominating populations such as the Han Chinese.
This supports the theory of an early first migration wave out of Africa into Asia about 70,000 years ago that then encountered Denisovans and interbred. Thus there are two implications: Denisovan probably settled far further south than Siberia (were the original fragment was found). And they were no longer around when a second wave of modern humans arrived in Asia some ten thousand years later.
The HP board really knows how to pick 'em, doesn't it?
It is a testament to the employees resourcefulness that HP is still as strong as it is after this remarkable serial abuse by incompetent top management. Not sure how much more abuse the company can take.
I googled the subject many times over the years and found some good stuff, yet some things that have been recommended here I had not stumbled upon. So I found this slashdot story quite helpful.
Google's ranking system is a poor substitute for the judgment of people who actually studied the subject.
On the other hand I would have never asked for help here at/. due to the high anti-social quota.
Where are my mod points when there's an AC comment to be rescued from obscurity.
Myvirtualid doesn't offer bad advice but the AC's comment is also spot on. You only get so far without the math.
I studied physics but never took classes on topology and differential manifolds and this severely hampers me in getting a good grip on GR although I am perfectly comfortable with Einstein's thought experiments.
So in a sense I agree with myvirtualid's stance: Don't start with the math but you will need it later and then the math may lead you to completely new insights as pointed out by the AC.
Fair enough, but wouldn't this be an even better argument for sampling from various individuals? Other wise how are you going to determine where the deltas are?
I am in no position to judge the biological relevance of this 1% error.
But I am also puzzled why the focus is on one individual's DNA. Wouldn't it make more sense to work with samples of several individuals in order to throw out the - presumably minute - individual variances? I would expect the latter not to be very helpful for medical research.
if the techniques used don't account for mycoplasma contamination then all the samples will be affected.
If indeed the contamination is that common it'll amount to what would be considered a systematic error in my field (Disclaimer: my academic background is physics).
Usually this means going back to the drawing board and figuring out how to collect clean data unless you're lucky and can exactly isolate how the data was skewed and it doesn't add too much noise. In that case you can still filter out the information you're after.
Since I am not a biologist I can only guess that this implies that you need to know the entire possible parameter space of the mycoplasma genome (I assume there is more than one variant). Even then as you point out I don't see how it's possible to control for not erroneously removing human genes if we share some proteins with this critter.
I read this as cleaning up an already corrupted database. Hence my question why you don't go back to the source? Preferably repeatedly and independently to have a better statistic in separating "noise" i.e. Mycoplasma from "signal" i.e. human genome.
My understanding is that nowadays new high speed sequencing machine can get an entire human genome processed in a couple of month.
So I would think that after a couple of independent runs one should be able to flush out the non-human DNA assuming the same bacteria contamination is not ever present?
Obviously this is not a cheap endeavor but given that there is quite a bit of commercial interest in using correct human genome data this seems to me to be a worthwhile investment.
I find it puzzling that the abstract of the article does not allude to this.
I have an option to upgrade my old corporate provided blackberry.
The supported phones that I can chose from are:
Blackberry Torch
iPhone
Dell Streak
If I wanted a consumer device only I'd go with the iPhone. But as a consultant who is on the road quite a bit email functionality is still key to me.
I am still considering the iPhone if there is an easy way to pair it to my Laptop so that I have a decent keyboard.
Yet, all Torch users I've been talking to were very happy with the device.
On the other hand I am just inclined to wait and see if you can do better. For now my old blackberry does what I need it for. For play time I have an Notionink Adam at home. Wouldn't want any corporate data on that device for sure.
I think if you keep your focus on the business crowd i.e. security, reliability, long battery life, good remote admin tools, keyboard, key business apps you'll remain the guys to beat in that domain.
BTW originally I hated my Blackberry having been forced to give up my Moto A760. But it won me over. What it does is what I need to do my job and what it does it does well.
My mother used to share your fantasy during the first big OPEC oil crisis. She is an avid horse woman and was very much looking forward to it. I am quite comfortable on a horse as well and am sorry that I don't find the time any more for this beautiful sport.
Makes me wish we could really go back to horses. People would be in such better shape.
Slashdot Mirror
This is based on Einstein's field equation using perturbation theory to construct a solution for the examined case.
My bet is on general relativity once again delivering the goods. Quite a strike against the case for dark matter.
Which several analyses of the cosmic microwave background suggest may in fact not be valid assumptions.
With regards to this I really like this new theory. It has the advantage of also doing away with dark energy.
The invariance of a particular speed in all inertial frames.
This you can use as an experimentally verified starting point if you go with the mainstream interpretation of Michelson-Morley. All the rest follows very easily by just drawing a Minkowski diagram. No need to go through the whole clock syncing rigmarole. The LT are immediately accessible.
But again, you don't need that shortcut if you take the much more general approach outlined in the 1976 paper. The latter is certainly the way I'd introduce it to a student.
This is an unfortunate and very common misconception. Most textbooks still follow the clock synchronization route to SR because that is how Einstein derived it in the first place. But as with most theories the oldest presentation and approach is usually not the best or most elegant one.
To derive SR all you need is some basic assumptions about space and time (homogeneity, isotropy) and one extra bit that you don't find in classical physics: The invariance of a particular speed in all inertial frames.
A nice presentation how this leads to SR can be found in this rather remarkable textbook that otherwise mostly deals with QM (Disclaimer: I am not the author nor do I know him or benefit otherwise from an endorsement).
Yet, there is even a more general approach to SR that can be taught on an introductory level. Here the assumption of an invariant speed is not required either and substituted by group law first principles that feel just as intuitively right as the assumption that space is homogeneous and isotrope. Namely we require that our transformations must always have an inverse one and a composition of them must result in the same class of transformations. Out pops SR.
This paper is really a thing of beauty. Professor who still teaches SR starting with clock synchronization should be punished to copy it by hand until their fingers bleed.
The sad thing is it has already been published 1976!
But to this day SR is still taught following Einstein's original convoluted path. Of course with the predictable results.
In quantum physics we are already accustomed to situations were the measurement, i.e. act of observation, can determine a particular physical outcome.
If superluminal neutrinos are real we may have a similar situation. I.e. they can only be measured as faster than light in a reference frame if no measurement is attempted in another frame that'll break causality.
Let's just call it "Quax's principle" :)
They imply that light speed is an invariant under coordinate transformation i.e. the implicitly contain the Lorentz transformations. The explicit experimental confirmation for this invariance of c is the MichelsonMorley experiment..
'we screwed up but we don't know why so look at these'
Really don' t think that is how they put it. But maybe you watched the CERN webcast and know something I don't.
My understanding is that they started looking for this effect because it was speculated about in this paper.
Some quantum gravity models allow for subliminal neutrino dispersion.
Yet, given how extraordinary this results is you certainly want to make sure every aspect of it is thoroughly scrutinized.
Quantum computing is adiabatic computing. I.e. fully reversible without entropy increase. Hence a complex quantum computation is theoretically not an my more energy intensive then a simple one. Entropy only increases at the end when the final measurement is performed.
What makes the process tricky is keeping quantum coherence over the length of the algorithm.
What stood out to me was that they found about 5% Denisovan DNA. The latter being an early human that evolved independently from Homo erectus. This genome can also be found in some other Asian aboriginal populations but not modern day dominating populations such as the Han Chinese.
This supports the theory of an early first migration wave out of Africa into Asia about 70,000 years ago that then encountered Denisovans and interbred. Thus there are two implications: Denisovan probably settled far further south than Siberia (were the original fragment was found). And they were no longer around when a second wave of modern humans arrived in Asia some ten thousand years later.
The HP board really knows how to pick 'em, doesn't it?
It is a testament to the employees resourcefulness that HP is still as strong as it is after this remarkable serial abuse by incompetent top management. Not sure how much more abuse the company can take.
Good luck!
Truer words were never posted.
No high priced outfit will allow such cyber squatting of their realty.
They will unleash hordes of lawyers to peel back the augmented reality layers.
When did /. become a tabloid?
Let me take a stab at this: About maybe 8 years ago?
I googled the subject many times over the years and found some good stuff, yet some things that have been recommended here I had not stumbled upon. So I found this slashdot story quite helpful.
Google's ranking system is a poor substitute for the judgment of people who actually studied the subject.
On the other hand I would have never asked for help here at /. due to the high anti-social quota.
No reason to invite unwarranted abuse.
Where are my mod points when there's an AC comment to be rescued from obscurity.
Myvirtualid doesn't offer bad advice but the AC's comment is also spot on. You only get so far without the math.
I studied physics but never took classes on topology and differential manifolds and this severely hampers me in getting a good grip on GR although I am perfectly comfortable with Einstein's thought experiments.
So in a sense I agree with myvirtualid's stance: Don't start with the math but you will need it later and then the math may lead you to completely new insights as pointed out by the AC.
Damn, I read /. long before I bothered to sign up.
Little did I know this could turn into a geek badge of honor.
Anyhow: Goodbye Rob and thanks for all the fish!
If I had mod points right now I'd threw some your way. A fork seems very much in order.
Care to define "best" for us?
No offense, but it boggles the mind that such a throw-away comment is regarded as +5 "Insightful" by the /. hive-mind.
Fair enough, but wouldn't this be an even better argument for sampling from various individuals? Other wise how are you going to determine where the deltas are?
I am in no position to judge the biological relevance of this 1% error.
But I am also puzzled why the focus is on one individual's DNA. Wouldn't it make more sense to work with samples of several individuals in order to throw out the - presumably minute - individual variances? I would expect the latter not to be very helpful for medical research.
if the techniques used don't account for mycoplasma contamination then all the samples will be affected.
If indeed the contamination is that common it'll amount to what would be considered a systematic error in my field (Disclaimer: my academic background is physics).
Usually this means going back to the drawing board and figuring out how to collect clean data unless you're lucky and can exactly isolate how the data was skewed and it doesn't add too much noise. In that case you can still filter out the information you're after.
Since I am not a biologist I can only guess that this implies that you need to know the entire possible parameter space of the mycoplasma genome (I assume there is more than one variant). Even then as you point out I don't see how it's possible to control for not erroneously removing human genes if we share some proteins with this critter.
I read this as cleaning up an already corrupted database. Hence my question why you don't go back to the source? Preferably repeatedly and independently to have a better statistic in separating "noise" i.e. Mycoplasma from "signal" i.e. human genome.
My understanding is that nowadays new high speed sequencing machine can get an entire human genome processed in a couple of month.
So I would think that after a couple of independent runs one should be able to flush out the non-human DNA assuming the same bacteria contamination is not ever present?
Obviously this is not a cheap endeavor but given that there is quite a bit of commercial interest in using correct human genome data this seems to me to be a worthwhile investment.
I find it puzzling that the abstract of the article does not allude to this.
I have an option to upgrade my old corporate provided blackberry.
The supported phones that I can chose from are:
If I wanted a consumer device only I'd go with the iPhone. But as a consultant who is on the road quite a bit email functionality is still key to me.
I am still considering the iPhone if there is an easy way to pair it to my Laptop so that I have a decent keyboard.
Yet, all Torch users I've been talking to were very happy with the device.
On the other hand I am just inclined to wait and see if you can do better. For now my old blackberry does what I need it for. For play time I have an Notionink Adam at home. Wouldn't want any corporate data on that device for sure.
I think if you keep your focus on the business crowd i.e. security, reliability, long battery life, good remote admin tools, keyboard, key business apps you'll remain the guys to beat in that domain.
BTW originally I hated my Blackberry having been forced to give up my Moto A760. But it won me over. What it does is what I need to do my job and what it does it does well.
It is pretty well established philosophically that there is no purely logical way to prove or disprove and existence of God (as usually imagined in the Christian) doctrine.
After all these kind of arguments have been going on for about forever.
It's called believe for a good reason. I don't mind believers of whatever persuasion as long as they don't stray onto the turf of science.
The catholic church after fighting this with their considerable power throughout the centuries finally wised up to the fact that they are fighting a loosing battle.
Pretty ironic: I guess if you don't want to have your kids subjected to Intelligent Design in the US you'd better send them to a catholic school.
Well, i guess it's appropriate for a dystopian fantasy but you do realize that there hasn't been Deutschmark in circulation since 31 December 2001, don't you?
My mother used to share your fantasy during the first big OPEC oil crisis. She is an avid horse woman and was very much looking forward to it. I am quite comfortable on a horse as well and am sorry that I don't find the time any more for this beautiful sport.
Makes me wish we could really go back to horses. People would be in such better shape.