
Concept design for a post-LHC future circular collider at CERN - est31
https://home.cern/news/press-release/accelerators/international-collaboration-publishes-concept-design-post-lhc
======
gigatexal
Less than 10 billion euros for something that will do amazing things for
science? Where do I donate?

~~~
kgwgk
> something that will do amazing things for science

Maybe it will, maybe it won't.

[http://backreaction.blogspot.com/2019/01/particle-
physicists...](http://backreaction.blogspot.com/2019/01/particle-physicists-
want-money-for.html)

[http://backreaction.blogspot.com/2018/12/cern-produces-
marke...](http://backreaction.blogspot.com/2018/12/cern-produces-marketing-
video-for-new.html)

~~~
selectodude
Can anybody explain why we know there's exciting stuff at 15 orders of
magnitude more power than what we currently have? I'm off today and I'd love
to fall into a high-energy particle physics wikipedia wormhole.

~~~
walrus1066
That's the energy scale where the force of gravity becomes strong enough to
influence subatomic particle interactions.

Currently, our model of nature at subatomic scales (the 'Standard Model') does
not include gravity. This is fine for LHC energy scale, because gravity is so
weak compared to the other three forces (electromagnetism, strong & weak
nuclear force), that it can be ignored. The mass of quarks, electrons etc is
tiny, you can make precise predictions on stuff like 'particle X will decay
into particles Y & Z at this likelihood', without accommodating gravity.

But at the planck energy scale, gravity is too strong to be ignored, and the
Standard Model breaks down, it can't make predictions. So this is why the
planck scale is where you're 100% guaranteed to see 'new physics'.

[https://en.m.wikipedia.org/wiki/Planck_units](https://en.m.wikipedia.org/wiki/Planck_units)

EDIT: think the reason gravity becomes stronger at higher energies, is because
the _relativistic mass_ of particles increases with their velocity.

So if you bang two electrons a&b together at nearly the speed of light, the
effective mass of electron a from the frame of reference of electron b will be
orders of magnitude greater than the 'rest mass of electron a'. Because
strength of gravitational interaction is proportional to mass of particles
involved, electron b will feel stronger gravitational pull of electron a (and
vice versa).

So if the electrons are traveling at planck scale speeds, the strength of
gravitational interaction becomes comparable to the electromagnetic
interaction between them. Then all standard model predictions of how the
electrons interact goes out of the window, because SM cannot model gravity.

[https://en.m.wikipedia.org/wiki/Mass_in_special_relativity](https://en.m.wikipedia.org/wiki/Mass_in_special_relativity)

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PhilWright
As the Higgs fills in the last missing particle for the Standard Model,
creating such a new accelerator seems very speculative. Maybe there is nothing
else to find at higher energies, there is no hint of them at the LHC and the
Standard model does not predict anything. I understand professionals always
want more experimental power, but given the $10billion+ cost, it seems hard to
justify.

~~~
verytrivial
Yes, I found Sabine Hossenfelder's summary of LHC++ rather sobering.
[http://backreaction.blogspot.com/2018/12/cern-produces-
marke...](http://backreaction.blogspot.com/2018/12/cern-produces-marketing-
video-for-new.html?m=1) (Very interesting blog, BTW)

~~~
orbifold
She does not work in the field and is not an expert. She also has an axe to
grind, because she barely got tenure after many years in academia.

------
DFXLuna
Looks like SERN is moving ahead of schedule.

Be safe.

El Psy Congroo

~~~
TeMPOraL
I may or may not have a pristine IBM 5100 for sale.

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fasteddie31003
Has there been any progress of the AWAKE accelerator technology?
[https://home.cern/science/experiments/awake](https://home.cern/science/experiments/awake)
Seems like that could be a cheaper method of particle acceleration.

~~~
magicalhippo
There was a discussion over at Physics Forums regarding wakefield
acceleration.

[https://www.physicsforums.com/threads/two-stage-electron-
wak...](https://www.physicsforums.com/threads/two-stage-electron-wakefield-
acceleration.948303/)

Note that mfb works as a physicist in the CMS detector team, Vanadium 50 and
ZapperZ are current or have been high-energy physicists as well.

In summary, issue seems to be that the strong acceleration provided reduces
beam quality, which kind of negates the gains you got from the higher energy.
Though it doesn't seem to be a fundamental limitation, just a difficult
engineering issue.

~~~
dukwon
I always thought mfb worked on ATLAS

~~~
magicalhippo
I can't find the reference right now, but in one thread he said something
about how the CMS team did their analysis and then commented along the lines
that ATLAS did something similar but he wasn't sure of the details. That's why
I got the impression he was on the CMS team.

Anyway, he works with one of them, so he's not just a random internet armchair
expert was my point :)

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sandworm101
I'd support this if there was some notion of compromise, some sharing of the
load between projects. Why not build the new ring to incorporate the current
detector halls? Get the ring 90% done, then punch through into one of the
existing LHC detector arrays. Use as much of the current LHC equipment as
possible. Once those abilities have been maxed, then move forwards with costly
new detectors.

~~~
jessriedel
The detectors are heavily, heavily optimized based on the properties of the
beam, and they are not that expensive compared to the cost of the accelerator,
operations, and data analysis.

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nraynaud
wouldn't it be better to put it where the ground is not active?

~~~
fasteddie31003
I'd also put it where labor prices are not the highest in the world.

~~~
m_mueller
tunneling in Switzerland is actually reasonable compared internationally. Take
a look at the NEAT project. Roughly 100km of tunnels built for 22bn or so, in
highly difficult terrain. NYC built like a couple of km and a station for
almost the same cost.

~~~
nraynaud
my understanding is that they had very bad difficulties drilling in CH for the
Gotthard project: [http://www.spiegel.de/international/europe/the-gotthard-
base...](http://www.spiegel.de/international/europe/the-gotthard-base-tunnel-
miracle-under-the-alps-a-723202.html) .

~~~
m_mueller
my point was that despite all these difficulties, long duration and it being
Switzerland, cost was actually reasonable. ~22M / tunnel kilometer is an order
of magnitude lower than many other projects abroad. In general I find public
infrastructure projects here to be well run and within reasonable budget. With
these kinds of things, labour cost seems to be less of important than
inefficiences due to administration and legal uncertainties (unions, nimbys
etc.)

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lokimedes
Good news, but it’s not a CDR collider. It collides particles not reports.

~~~
FreeFull
Technically reports are made out of particles, though

