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An energy of 13 TeV in the center-of-mass frame means that you can produce particles with a total invariant mass of up to 13 TeV/c^(2). So for example, you could produce a particle/antiparticle pair where each particle has a mass of 6.5 TeV/c^(2).

>With GUT energy and Plank Energy occurring at from what I understand at a order of magnitude of around 1025eV and 1 X 1028eV why do some physicists believe they will find new physics at say 200TeV?

There could still be new physics between what we've currently observed and where we expect the GUT scale to be.

How likely could that be? And the range of the next colliders only go up like 1 I order of magnitude from what I understand. Far away from what the GUT scale might be: I only ask because I was reading about criticisms of new particle colliders and some physicists believe if the next collider is anything below like 200TeV it won’t be worth the money as it’s essentially guessing in the dark.

And also the same physics said that only use would be to rule out theories that are more likely than not false.

With some exceptions for certain kinds of hypothetical phenomena, where we have reason to expect a certain energy scale or range of energy scales (like how we expected to find the W and Z bosons around the scale of the Fermi constant, roughly 100 GeV), it seems to be generally considered unlikely.

High-energy particle physicists often consider what is known as the [desert](https://en.wikipedia.org/wiki/Desert_(particle_physics)), which is a large gap in energy scales between the electroweak and strong scales where no significant new physics is anticipated to be found.

There are some valid reasons to be skeptical about whether there is such a desert though, of course, and there are certain classes of hypothetical phenomena that are proposed to lie within the desert, such as heavy superpartners to each of the known particles if supersymmetry exists but is spontaneously broken in nature, or heavy sterile neutrinos if right-handed neutrinos exist and there is a see-saw mechanism that drives the right-handed neutrinos to have very heavy masses while driving the left-handed neutrinos to have very light masses.

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Well it comes to the theories themselves I understand they have certain eV ranges. Are these ranges gigantic ? I read somewhere that while the current large hadron detector has constrained Large Extra dimensions. It still seems to suggest that the possible eV Range of detections of what I assume is either branes or some kind of extra dimensions goes all the way from 3TeV which is what apparently we have checked so far goes possibly up to the GUT scale itself.

Does that mean unless we build some kind of Gigantic particle collider that is somehow the distance of Earth to Mars. We may very well never reach these scales for possibly centuries? Can you observe certain phenomenon at those scales with telescopes from some mechanism. I’m sorry if I’m asking a billion questions this stuff is just amazing to me.

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In principle yes, in practice the range is lower for most particles. Searches for microscopic black holes are the only example I know that comes close to the collision energy.

Protons are composite particles, and can be treated as collection of quarks and gluons each carrying some part of their energy. What we actually study (in most cases) are collisions of one quark or gluon from one proton with one quark or gluon from the other proton, so the effective collision energy is lower. The rest of the protons does some lower energy stuff we usually don't care about (LHCf physicists, don't hurt me).

In addition, many proposed particles would be produced in pairs, so you need at least twice their mass as collision energy. Sometimes they are only produced together with other particles, then you need energy for them as well. And finally the cross section (which tells us the probability of a process) is very low if you have just the minimum amount of energy required: It would mean all particles are almost at rest relative to each other, which comes with a very small phase space.

Combine all that and most searches are happening in the range of 100 GeV to 2000 GeV. We also look for particles with lower energy, but previous accelerators could look for them already, and particles with higher energy, but often we don't have enough statistics to limit theory models.

Going to 100-200 TeV collision energy would give us another order of magnitude in energy and increase the useful search range by a similar factor, yes. It's possible that there is nothing, but it would be unusual - so far we always found something new when increasing the energy significantly. Finding something not too far away could also solve some open questions about the particles we have found already, e.g. why the Higgs boson is relatively light.

Particles can be discovered even when the energy is not sufficient to produce them directly. They can alter properties of existing particles, like their production or decay modes. These indirect searches are harder to interpret (if they find a deviation from the Standard Model), but they can potentially find signs of particles far heavier than the collision energy.

>Well it comes to the theories themselves I understand they have certain eV ranges. Are these ranges gigantic ?

The gap between the electroweak and GUT scales is pretty gigantic. As for theories of new physics between them, it depends on the theory. Some have narrower constraints on their possible ranges than others.

>It still seems to suggest that the possible eV Range of detections of what I assume is either branes or some kind of extra dimensions goes all the way from 3TeV which is what apparently we have checked so far goes possibly up to the GUT scale itself.

Yes, my understanding is that colliders like the LHC can only raise the lower limit on the energy scale (or equivalently, lower the upper limit on the length scale) at which any small extra dimensions could become apparent, but since there isn't really any way to place an upper limit I am aware of, the range of possibilities is quite large.

>Does that mean unless we build some kind of Gigantic particle collider that is somehow the distance of Earth to Mars. We may very well never reach these scales for possibly centuries?

Essentially, yes. We can keep making incremental improvements — perhaps even a few substantial leaps — but speaking frankly a lot of the hypothetical higher-energy phenomena that is closer to the GUT scale are likely to be practically inaccessible to us for ... well, probably more than just centuries. Personally I place the likelihood that human civilization peaks and wanes to be greater than the likelihood that we ever make it far enough to test any physics that might lie near the GUT scale.

>Can you observe certain phenomenon at those scales with telescopes from some mechanism.

Only if you can find a natural system out there in the cosmos which both exhibits those phenomena and is observable with a telescope. Some important high-energy phenomena, such as those at the surface of a neutron star, might become observable (but also with some very dramatic improvements in telescope capacities). But it's not like we could point a telescope and see things like individual particles out there in space, especially not high-energy particles that nearly instantly decay after being produced. That might happen in, say, a supernova event, but imagining the feat of engineering it would take to make such tiny and precise measurements in the vicinity of a supernova without being obliterated ... it's probably much simpler to just create any such particles in a laboratory on or near Earth, even if it does take up such an enormous amount of energy to access.

>I’m sorry if I’m asking a billion questions this stuff is just amazing to me.

Nah, no worries, it is good that you are curious! :) You are asking good and thoughtful questions; keep 'em coming if you like!

Cheers,

Hahaha thank you for the answers

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