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It means that another way in which the standard model could have been broken doesn't appear, at first glance, to be broken. Improved colliders, and improved ex

by ISL 8y ago

It means that another way in which the standard model could have been broken doesn't appear, at first glance, to be broken. Improved colliders, and improved experiments generally, tend to increase the number of ways in which we can search for a departure from the plan. What we may need, at least as much as new colliders, is the right insight to open a new way forward. The standard model is large and complicated -- there aren't that many people who really understand its complexity enough to find something analogous to Gell-Mann's eightfold way.

erickj 8y ago
At roughly what scale would new colliders need to increase by to open new paths? Are proposal estimating new efforts at 100's of km? 1000s?
- chriswarbo 8y ago
  The problem is that it's very difficult to rule out most hypotheses, since they can be tweaked to avoid whatever a particular experiment said. Usually this means that colliders can't rule out a hypothesis; they can only put a limit, like "no effect is observed below energies of 14TeV". Rather than trying to rule out a hypothesis completely, it's easier to place limits outside of which a hypothesis is essentially useless. IIUC, if the LHC didn't spot the Higgs mechanism below 14TeV then that wouldn't work as an explanation of other particles' mass. At that point there might have still been a Higgs mechanism at higher energies, but we wouldn't really care either way since the whole point of coming up with the Higgs mechanism was to explain the mass of other particles: if it can't do that, it becomes inconsequential. That's why the LHC was so important for the Higgs: we would either find it, and hence have a better explanation of particles' mass; or we would know that particle mass doesn't follow the Higgs mechanism. At the moment we have a bunch of hypotheses which predict effects that larger colliders might see, but I don't think we have (feasible) limits which let us discard these hypotheses. Hence new colliders don't have a goal to aim at: it's just a case of going as big as possible to have the highest chance of seeing new effects. Yet we might see nothing, and that wouldn't actually tell us much, since the predictions could just be tweaked again.
  - whatshisface 8y ago
    An analogy I like is a person in a primitive culture planning an expedition to determine the curvature of their planet. How far do they have to go until it is detectable? Well, it depends on the curvature, which is what they're trying to find out in the first place.

by ISL 8y ago

erickj 8y ago

At roughly what scale would new colliders need to increase by to open new paths? Are proposal estimating new efforts at 100's of km? 1000s?

chriswarbo 8y ago
The problem is that it's very difficult to rule out most hypotheses, since they can be tweaked to avoid whatever a particular experiment said. Usually this means that colliders can't rule out a hypothesis; they can only put a limit, like "no effect is observed below energies of 14TeV". Rather than trying to rule out a hypothesis completely, it's easier to place limits outside of which a hypothesis is essentially useless. IIUC, if the LHC didn't spot the Higgs mechanism below 14TeV then that wouldn't work as an explanation of other particles' mass. At that point there might have still been a Higgs mechanism at higher energies, but we wouldn't really care either way since the whole point of coming up with the Higgs mechanism was to explain the mass of other particles: if it can't do that, it becomes inconsequential. That's why the LHC was so important for the Higgs: we would either find it, and hence have a better explanation of particles' mass; or we would know that particle mass doesn't follow the Higgs mechanism. At the moment we have a bunch of hypotheses which predict effects that larger colliders might see, but I don't think we have (feasible) limits which let us discard these hypotheses. Hence new colliders don't have a goal to aim at: it's just a case of going as big as possible to have the highest chance of seeing new effects. Yet we might see nothing, and that wouldn't actually tell us much, since the predictions could just be tweaked again.
- whatshisface 8y ago
  An analogy I like is a person in a primitive culture planning an expedition to determine the curvature of their planet. How far do they have to go until it is detectable? Well, it depends on the curvature, which is what they're trying to find out in the first place.