5 ms·

Physicists extend special relativity

61 points by soofy 14y ago

lloeki 14y ago
> I have a feeling the world will change in some dramatic way as we move through the speed of light. All sorts of things could happen. Time and space could interchange. Penrose diagrams, light cones and scenarios like approaching a black hole event horizon help a lot on gathering what he means here.
soofy 14y ago
Quote from original paper: "In this highly controversial topic, our particular purpose is not to enter into the merits of existing theories, but rather to present a succinct and carefully reasoned account of a new aspect of Einstein's theory of special relativity, which properly allows for faster than light motion." http://bit.ly/RswJIr http://bit.ly/RswJIr
_of 14y ago
Seems like an interesting article, sad that it is behind a paywall.
- geuis 14y ago
  Apologies. Did you mean this? http://rspa.royalsocietypublishing.org/content/early/2012/09/25/rspa.2012.0340.abstract http://rspa.royalsocietypublishing.org/content/early/2012/09...
  - deleted 14y ago
    [deleted]
  - andyjohnson0 14y ago
    The article on phys.org is a summary of a paper published in Proc Royal Soc, the abstract for which is at [1]. The full paper is paywalled, and I believe that this is what @_of is referring to. Unfortunately there doesn't seem to be a preprint on ArXive. Edit: All articles since November 2010 seem to be paywalled. [1] http://rspa.royalsocietypublishing.org/content/early/2012/09/25/rspa.2012.0340.abstract http://rspa.royalsocietypublishing.org/content/early/2012/09...
geuis 14y ago
Don't editorialize the title. The title of the article is "Physicists extend special relativity beyond the speed of light"
oneandoneis2 14y ago
..I was under the impression that special relativity only forbade accelerating to the speed of light - particles that always traveled FTL (i.e. tachyons) were explicitly fine. So.. what have they added with this work, exactly? IDGI.
- andyjohnson0 14y ago
  That was my understanding too. Although its worth noting that the existence of Tachyons is entirely speculative.
- stargazer-3 14y ago
  Tachyons have complex mass, for one thing. The authors described the way to move between frames of reference of superluminal particles, so that they (particles) seem to have real finite physical properties. At least that's my understanding.
  - cygx 14y ago
    There are two different concepts of tachyons: Quantum fields with imaginary mass and faster-than-light particles. Tachyonic fields still (anti)commute at space-like separation, which preserves causality. Such fields are maximally unstable and do not permit a particle picture. They are used to describe spontaneous symmetry breaking. Tachyonic particles are a concept from special relativity. While one can also attribute an imaginary mass to such particles, this basically encodes a sign convention. These theoretical particles exhibit some perculiar properties (zero-energy particles which travel at infinite velocity and finite momentum, different observers will disagree on emitter and absorber - in fact, during a tachyonic interaction, both endpoints may claim to be emitter or absorber in their respective rest frames depending on their relative motion, ...). According to Recami[1], no causal paradoxa occur. [1] http://dinamico2.unibg.it/recami/erasmo%20docs/SomeRecentSCIENTIFICpapers/ExtendedRelativity/TachyonCausalParadoxesSOLVED.pdf http://dinamico2.unibg.it/recami/erasmo%20docs/SomeRecentSCI...
nik61 14y ago
No need to travel faster than the speed of light if you can cross the universe in 19 days? http://www.fourmilab.ch/documents/OhMyGodParticle/ http://www.fourmilab.ch/documents/OhMyGodParticle/ Of course, everything will be dust before you get back including all your friends and relations. This might be difficult for everyone involved to cope with?
deleted 14y ago
[deleted]
tokenadult 14y ago
Several comments here are reminding me of general objections to PhysOrg as a source. As I recall, PhysOrg appears to have been banned as a site to submit from by Reddit. Users here on HN think there are better sites to submit from. Comments about PhysOrg: http://news.ycombinator.com/item?id=3077869 http://news.ycombinator.com/item?id=3077869 "Yes Physorg definitely has some of the worst articles on the internet." http://news.ycombinator.com/item?id=3198249 http://news.ycombinator.com/item?id=3198249 "Straight from the European Space Agency, cutting out the physorg blogspam: http://www.spacetelescope.org/news/heic1116/ http://www.spacetelescope.org/news/heic1116/ (press release), http://www.spacetelescope.org/videos/heic1116a/ http://www.spacetelescope.org/videos/heic1116a/ (video), http://www.spacetelescope.org/static/archives/releases/science_papers/heic1116.pdf http://www.spacetelescope.org/static/archives/releases/scien... (paper). "PhysOrg: just say no." http://news.ycombinator.com/item?id=3611888 http://news.ycombinator.com/item?id=3611888 "The physorg article summary is wrong, I think." http://news.ycombinator.com/item?id=4108857 http://news.ycombinator.com/item?id=4108857 "Phys.org is vacuous and often flat wrong."
- netcat 14y ago
  Could you point to alternatives? I read phys.org since it has a useable mobile interface, which is a lot cleaner than the somewhat cluttered main page. Reading news by categories is also a bonus, I especially like the Other Sciences category. I know of eurekalert.org, but since they have no mobile site that's a no go. Also, I think of them less as blogspam than as a news aggregator. I can't read all the direct press releases, so having the info all in one place and categorized is nice.
- soofy 14y ago
  I also gave link to the original article. PhysOrg also gives link to the original article and cites a few other sources. I thought in this particular cases it was fine as an overview article.
caller9 14y ago
So is this just saying that a particle traveling at .75 c will appear to be moving at 1.5 c to another particle moving towards it at .75 c? If so then duh?
- Tuna-Fish 14y ago
  > So is this just saying that a particle traveling at .75 c will appear to be moving at 1.5 c to another particle moving towards it at .75 c? If so then duh? The real DUH is that it doesn't. A particle that is moving at .75c towards an observer going at it at .75c would appear to move at .96c. Velocities cannot be composited like that when you are moving really fast.
  - deleted 14y ago
    [deleted]
- sageikosa 14y ago
  No. If: V(a)=0.75c (relative to observer at (c)) and V(b)=0.75c (relative to observer at (c)) and (a) and (b) appear to be on parallel and oppositely signed vectors from (c)'s vantage point, the observed velocity of (b) @ (a), or (a) @ (b) will not equal 1.5c.
warmwaffles 14y ago
Well the answer is obvious. Just make light go faster.
- mcguire 14y ago
  I've giv'n her all she's got, an' I canna give her no more.
DennisP 14y ago
I wish the full paper were available. Stepping into general relativity, there's been a fair amount of work lately on Alcubierre's warp drive idea. The original required enormous amounts of negative mass and was infeasible in other ways, but more recent papers have modified it in ways that almost sound workable. Now a guy at NASA named Harold White is trying an experiment. (Google turns up plenty of articles.) Not directly related: experiments continue on Woodward's Mach effect idea.

61 points by soofy 14y ago

> I have a feeling the world will change in some dramatic way as we move through the speed of light. All sorts of things could happen. Time and space could interchange. Penrose diagrams, light cones and scenarios like approaching a black hole event horizon help a lot on gathering what he means here.

soofy 14y ago

Quote from original paper: "In this highly controversial topic, our particular purpose is not to enter into the merits of existing theories, but rather to present a succinct and carefully reasoned account of a new aspect of Einstein's theory of special relativity, which properly allows for faster than light motion." http://bit.ly/RswJIr http://bit.ly/RswJIr

_of 14y ago

Seems like an interesting article, sad that it is behind a paywall.

geuis 14y ago
Apologies. Did you mean this? http://rspa.royalsocietypublishing.org/content/early/2012/09/25/rspa.2012.0340.abstract http://rspa.royalsocietypublishing.org/content/early/2012/09...
- deleted 14y ago
  [deleted]
- andyjohnson0 14y ago
  The article on phys.org is a summary of a paper published in Proc Royal Soc, the abstract for which is at [1]. The full paper is paywalled, and I believe that this is what @_of is referring to. Unfortunately there doesn't seem to be a preprint on ArXive. Edit: All articles since November 2010 seem to be paywalled. [1] http://rspa.royalsocietypublishing.org/content/early/2012/09/25/rspa.2012.0340.abstract http://rspa.royalsocietypublishing.org/content/early/2012/09...

geuis 14y ago

Don't editorialize the title. The title of the article is "Physicists extend special relativity beyond the speed of light"

oneandoneis2 14y ago

..I was under the impression that special relativity only forbade accelerating to the speed of light - particles that always traveled FTL (i.e. tachyons) were explicitly fine. So.. what have they added with this work, exactly? IDGI.

andyjohnson0 14y ago
That was my understanding too. Although its worth noting that the existence of Tachyons is entirely speculative.
stargazer-3 14y ago
Tachyons have complex mass, for one thing. The authors described the way to move between frames of reference of superluminal particles, so that they (particles) seem to have real finite physical properties. At least that's my understanding.
- cygx 14y ago
  There are two different concepts of tachyons: Quantum fields with imaginary mass and faster-than-light particles. Tachyonic fields still (anti)commute at space-like separation, which preserves causality. Such fields are maximally unstable and do not permit a particle picture. They are used to describe spontaneous symmetry breaking. Tachyonic particles are a concept from special relativity. While one can also attribute an imaginary mass to such particles, this basically encodes a sign convention. These theoretical particles exhibit some perculiar properties (zero-energy particles which travel at infinite velocity and finite momentum, different observers will disagree on emitter and absorber - in fact, during a tachyonic interaction, both endpoints may claim to be emitter or absorber in their respective rest frames depending on their relative motion, ...). According to Recami[1], no causal paradoxa occur. [1] http://dinamico2.unibg.it/recami/erasmo%20docs/SomeRecentSCIENTIFICpapers/ExtendedRelativity/TachyonCausalParadoxesSOLVED.pdf http://dinamico2.unibg.it/recami/erasmo%20docs/SomeRecentSCI...

nik61 14y ago

No need to travel faster than the speed of light if you can cross the universe in 19 days? http://www.fourmilab.ch/documents/OhMyGodParticle/ http://www.fourmilab.ch/documents/OhMyGodParticle/ Of course, everything will be dust before you get back including all your friends and relations. This might be difficult for everyone involved to cope with?

deleted 14y ago

[deleted]

tokenadult 14y ago

Several comments here are reminding me of general objections to PhysOrg as a source. As I recall, PhysOrg appears to have been banned as a site to submit from by Reddit. Users here on HN think there are better sites to submit from. Comments about PhysOrg: http://news.ycombinator.com/item?id=3077869 http://news.ycombinator.com/item?id=3077869 "Yes Physorg definitely has some of the worst articles on the internet." http://news.ycombinator.com/item?id=3198249 http://news.ycombinator.com/item?id=3198249 "Straight from the European Space Agency, cutting out the physorg blogspam: http://www.spacetelescope.org/news/heic1116/ http://www.spacetelescope.org/news/heic1116/ (press release), http://www.spacetelescope.org/videos/heic1116a/ http://www.spacetelescope.org/videos/heic1116a/ (video), http://www.spacetelescope.org/static/archives/releases/science_papers/heic1116.pdf http://www.spacetelescope.org/static/archives/releases/scien... (paper). "PhysOrg: just say no." http://news.ycombinator.com/item?id=3611888 http://news.ycombinator.com/item?id=3611888 "The physorg article summary is wrong, I think." http://news.ycombinator.com/item?id=4108857 http://news.ycombinator.com/item?id=4108857 "Phys.org is vacuous and often flat wrong."

netcat 14y ago
Could you point to alternatives? I read phys.org since it has a useable mobile interface, which is a lot cleaner than the somewhat cluttered main page. Reading news by categories is also a bonus, I especially like the Other Sciences category. I know of eurekalert.org, but since they have no mobile site that's a no go. Also, I think of them less as blogspam than as a news aggregator. I can't read all the direct press releases, so having the info all in one place and categorized is nice.
soofy 14y ago
I also gave link to the original article. PhysOrg also gives link to the original article and cites a few other sources. I thought in this particular cases it was fine as an overview article.

caller9 14y ago

So is this just saying that a particle traveling at .75 c will appear to be moving at 1.5 c to another particle moving towards it at .75 c? If so then duh?

Tuna-Fish 14y ago
> So is this just saying that a particle traveling at .75 c will appear to be moving at 1.5 c to another particle moving towards it at .75 c? If so then duh? The real DUH is that it doesn't. A particle that is moving at .75c towards an observer going at it at .75c would appear to move at .96c. Velocities cannot be composited like that when you are moving really fast.
- deleted 14y ago
  [deleted]
sageikosa 14y ago
No. If: V(a)=0.75c (relative to observer at (c)) and V(b)=0.75c (relative to observer at (c)) and (a) and (b) appear to be on parallel and oppositely signed vectors from (c)'s vantage point, the observed velocity of (b) @ (a), or (a) @ (b) will not equal 1.5c.

warmwaffles 14y ago

Well the answer is obvious. Just make light go faster.

mcguire 14y ago
I've giv'n her all she's got, an' I canna give her no more.

DennisP 14y ago

I wish the full paper were available. Stepping into general relativity, there's been a fair amount of work lately on Alcubierre's warp drive idea. The original required enormous amounts of negative mass and was infeasible in other ways, but more recent papers have modified it in ways that almost sound workable. Now a guy at NASA named Harold White is trying an experiment. (Google turns up plenty of articles.) Not directly related: experiments continue on Woodward's Mach effect idea.