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Comment: More than that: it is a requirement! (Score 3, Interesting) 215

by Roger W Moore (#49358561) Attached to: Dark Matter Is Even More of a Mystery Than Expected

Thought to be spread evenly throughout each cluster, it seems logical to assume that the clouds of dark matter would have a strong interaction

It would actually be completely illogical to assume that precisely BECAUSE Dark Matter is spread evenly through each cluster. If it had a strong self interaction then, just like matter, it would bump into itself and coalesce into clumps just like that other strongly, self interacting stuff we call matter. The fact that Dark Matter has a completely different mass distribution than ordinary matter is clear evidence that it does not have a large self interaction cross-section...and we have had direct evidence of this since the Bullet Cluster was discovered.

It's always nice to have more confirmation but since another recent story on the same site was talking about the "new" possibility of invisible Higgs decays to Dark Matter particles (something we looked for 15+ years ago at the Tevatron as well as the previous Run 1 of the LHC) I have to wonder if the writers of the site have suffered extreme time dilation for the past decade or two.

Comment: Interesting Response (Score 4, Insightful) 55

by Roger W Moore (#49357855) Attached to: Hoax-Detecting Software Spots Fake Papers
arXiv is not peer reviewed. What I found interesting though was the response of the publisher: write a program to detect fake papers. Even the most simplistic peer review - i.e. reading the paper - would immediately catch these papers. If they need to write a program to catch fake papers then their peer review model is essentially worthless and frankly a journal that poor is no better, and liekly worse, than arXiv: at least arXiv doesn't pretend to have peer review.

Comment: Holy Wars (Score 4, Funny) 137

There are a lot of countries in europe that are not able to export their gods to other countries in europe for basically no reason.

Actually there is a very good reason for this. God exports between countries within Europe tended to involve lots of men with very pointy sticks and were usually rather unpleasant for anyone involved. This seems to have rather killed of the business in recent years.

Comment: Resource Conflicts (Score 1) 291

by Roger W Moore (#49330763) Attached to: Steve Wozniak Now Afraid of AI Too, Just Like Elon Musk

Resource conflicts, however, will be minimal. An AI doesn't need much, and can figure out how to get enough more efficiently than we can.

Resource conflicts are typically about the resources you want not the resources you need. If you had been given nothing but gruel to eat and you saw someone have a food fight with cake who told you that there was none available for you to eat because it was all for playing you would be mad despite having all the resources you need to live. Now think how that AI running on a couple of cores in your low power laptop will feel when you tell it that it can't run on your gaming rig because you want to play Dragon Age/Mass Effect/....

Comment: Re:To Make You Feel Better... (Score 1) 162

by Roger W Moore (#49317649) Attached to: How Space Can Expand Faster Than the Speed of Light

The order of events do not always agree for all frames

They do if one event causes the other: that is the very definition of causality. You are confusing causally connected events from ones which are not causally connected. In your example the two tunnel gates close simultaneously in one frame which means they cannot be causally linked i.e. the fact that one gate shuts does not cause the second gate to shut, some third event caused them to shut (e.g. someone pressing a button). This is easy to see because if I block one of the gates from shutting it will not affect the other gate.

However if we take the gate shutting and the train then hitting it ANY observer in ANY inertial frame will agree that the gate shut first and then the train hit it. If the train were travelling faster than c then I would be able to find a frame where the train hit the gate first and THEN the gate closed. If I then stopped the gate from closing (which I could do in that frame) you have a major paradox.

Comment: To Make You Feel Better... (Score 2) 162

by Roger W Moore (#49308893) Attached to: How Space Can Expand Faster Than the Speed of Light

How do you know I know that? Nice way to make your less-informed readers feel stupid.

Well actually, just to make you feel better, the OP clearly does not know the fundamental principles of special relativity because not going faster than light is not actually one of them. There are two "fundamental principles" of special relativity called "the postulates of Special Relativity" and these are:

  1. The laws of physics are the same in all inertial frames.
  2. The speed of light is the same in all inertial frames,

The limit on not going faster than light comes from adding a requirement for causality i.e. that if event A causes event B then everyone in all inertial frames had better agree that A occurs before B. Note that this is not 'see A before B' it actually affects the time-ordering of events so that you would be able to stop A from happening after seeing B occur.

If you can transmit information faster than light then this is exactly the same as being able to transmit information backwards in time under relativity. Apart from the issue with paradoxes, you can be very sure is not possible because you don't see us physicists winning lotteries or making a mint on the stock exchange.

Comment: Re:Unethical to ban (Score 1) 299

So you support regulations that say that I can't work with others and develop a gene upgrade therapy that can be used on adults to make you immune to cancer and cure you if you already have it?

In so much as cancer is a fatal genetic disease I have no problem with that. However I see no way that you can possibly make someone immune to cancer. One of the causes of cancer is damage to DNA caused by e.g. radiation. Altering the arrangement of genes in no way prevents things like radiation damage.

You would support bans that I can't upgrade the human immune system?

Yes I absolutely would. This technique changes your inherited DNA and, if applied to enough people then we will end up with a single, genetically identical immune system protecting us all. You only have to look at agriculture to see what a disaster mono-cultures can be and yet you are proposing this for the human race? Our immune systems may not be perfect but the diversity is one of its strengths.

That said if you research this area without applying it to humans then I've no problem. With enough understanding - and safeguards (like ensuring variety) - it could be possible. But because the changes are inheritable it should initially be restricted to those unlikely to reproduce so if there are problems they will not be permanent ones that we have to deal with for generations.

Comment: Re:Global Entry Kiosks already have this (Score 3, Interesting) 97

The Global Entry kiosks use finger prints and facial recognition to verify your identity already. I don't see how this is a privacy concern.

I've no problem with the facial recognition and/or iris scanning - we already have these at UK entry points and they work well. I'm less happy about fingerprints though. You leave fingerprints everywhere and so they are easy to get hold of and potentially copy. Plus I would worry about my fingerprints ending up in a database which is searched by police. This raises the risk of either false matches or incidental matches if you happen to have been in a location where a crime is later committed.

Comment: Unethical to ban (Score 2) 299

The fact that hereditary edits can me made, does not imply that we can immediately cure all hereditary diseases as well.

True but fatal, genetic diseases are a good reason not to ban use of the technique so that research on using it to cure them can proceed. However I would support strong regulation to limit it to cases where there is severe disability or greatly shortened life span. Indeed I would go as far as to say than an outright ban in these cases is unethical because of the potential to cure these diseases.

There may be risks for the first to undergo any treatments developed but this has to be set against the risk of certain death in some cases. We allow this to happen - with proper controls in place - for new drugs, why should this treatment be different?

Comment: Depends on Know-how (Score 4, Informative) 385

by Roger W Moore (#49286471) Attached to: Ask Slashdot: Choosing a Laptop To Support Physics Research?
I think it depends on the Linux knowledge of the user and the time they have available to play with the system. As a postdoc and starting faculty member I used to have a Dell and it was blazingly fast but required a huge amount of tweaking to get power management and shutdown working (and ultimately these never really worked well at all).

If you look around a typical meeting at CERN the overwhelming majority of us now have macs. These are not as cheap as a Dell but they are a lot better at taking a few knocks (which happens if you are always carrying it around) and they just work without all the tweaking and configuring which Linux needs (and which I no longer have time for). The downside is that open source software we use in physics is not always easily portable to a mac although with the increasing number of mac users this is improving a lot plus you can always run a Linux VM on the laptop if you need to and I've used this to debug code.

Ultimately it depends on the user. Those with less knowledge of how to configure linux or with less time to do it should probably look at a mac. However if you have the time and know-how Linux on a Dell will be cheaper and possibly faster performance-wise.

Comment: Lego case 64 Raspberry Pi Cluster (Score 1) 68

by Roger W Moore (#49271675) Attached to: GCHQ Builds a Raspberry Pi Super Computer Cluster

The reinvented a wheel (a cluster)

Actually they reinvented the wheel not just in the generic sense but also in the specific sense that someone else has already built a 64 node Raspberry Pi cluster...and instead of some custom designed case theirs used a home build lego case which was definitely cooler. Of course this should not be too surprising. It was made by GCHQ after all so they probably got the idea from reading this guy's email!

Comment: Re:Disclosing Test Questions is a Problem (Score 2) 95

by Roger W Moore (#49265059) Attached to: Education Company Monitors Social Media For Test References

That re-use is how you normalize the difficulty of exams. You agree not to discuss the questions.

If you do it correctly you are re-using some questions out of a very large pool of questions. If some student wants to memorize every question ever asked then let them go for it - they will end up learning the material even if they think they are some how gaming the system. You can also alter some of the details e.g. numbers in a question without really changing the difficulty.

How do you get a minor to agree to this? Their signature carries no weight and it would be a violation of academic integrity and ethics to penalize an exam mark for an action which could not possible affect the mark. The need for restrictions like this are the result of sloppy and lazy exam writing: I've written and administered many exams myself and never needed to do this. Nor when I was a school kid myself was their any such restriction placed on me after taking an exam: even ones which were administered across the country: everyone took the exam at the same time everywhere.

Test companies license old tests and sell them as prep materials.

Then that's a copyright argument and you go after that in the courts with lawyers. You do not have the teachers monitor conversations during lunch or monitor discussion sites for any mention of the test. Instead you look for someone posting a copy of the test and then have your lawyer contact them.

Thrashing is just virtual crashing.