# Doubly Special Relativity

Zefram
What are the basic ideas behind this? What problems does it solve? What's "doubly special" about it? My knowledge of regular special relativity is pretty layman, with some of the easier (algrabraic) math mixed in.

So can anyone explain this easily? Is it cutting edge "wave of the future" stuff?

Staff Emeritus
Gold Member
All I know about it is that a new observer-independent scale is introduced, namely that of energy. Other accounts say it is length, mass, or momentum, but these differences are just a consequence of the use of natural units, I think.

Here is a short article on the subject:
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v418/n6893/full/418034a_r.html

Here are two articles written by the original theorist, Giovani Amelino-Camelia:
http://xxx.lanl.gov/PS_cache/gr-qc/pdf/0207/0207049.pdf
http://xxx.lanl.gov/PS_cache/gr-qc/pdf/0210/0210063.pdf

David had a really great post on this in PF v2.0, and he wrote an article for Nature magazine, I believe. When he comes back, you should bug him about it.

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FZ+
Newscientist, actually?
Any specific questions? I'll post a very basic PP article soon on it.

Zefram

Nothing really specific, FZ, I'm just wondering what it's all about and how it differs from regular special relativity.

Originally posted by Tom
All I know about it is that a new observer-independent scale is introduced, namely that of energy. Other accounts say it is length, mass, or momentum, but these differences are just a consequence of the use of natural units, I think.

This would be a revolutionary theory, it seems. If the observed energy and momentum are no longer considered to be linear, but would
be different in each frames of refference, this would mean that two bodies of different mass, observed to be traveling side by side in one observer's frame would be observed differently on a second frame, that is one body would travel faster than the other...the philosophical consequenses of such a theory would be tremendous; a theory of multy universes would arise from this.

mich

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heusdens
Here is another 'variation on the theme', what about the relativity of the measuring unit system? If measurements are relative, then why not also the measuring units?

Absurd? Weird?

Suppose we would use metrics/measuring units, in which the expansion of space would be a constant (measuring units 'grows' with the expansion of space). What kind of physics would we then get?