LHC Q&A

reply to post by TeraBlight


Once again, I see the same irresponsible and misleading argument from the scientists that have an interest themselves in the LHC at CERN. That argument is that we are safe because we are already bombarded with these particle collisions everyday, such as x-rays and gamma rays hitting the Earth's atmosphere. This is far from the truth and I will explain a few of the reasons why, and what the scientists are failing to report in their efforts to skirt the real issues with the LHC.

Cosmic rays hitting the Earth, are hitting a relatively stationary object on a cosmic scale at velocities below the speed of light. Most of these particles are deflected around the Earth by Earth's own magnetic field.
The particle collisions that they propose to do at the LHC, have protons accelerated to near the speed of light, but from opposite directions head-on into one another. This has the same effect of a proton hitting a stationary object at almost twice the speed of light, which HAS NOT been observed to occur in our natural universe that we know. This is very simple math... a no-brainer so to speak.

Einstein theorized that mass could not be accelerated faster than the speed of light, that once matter reached the speed of light, or greater, it would in fact become energy, and a collision could not happen, and those two sources of matter would simply pass right through one another upon their meeting. The fact that they are able to make a particle collision at above light speeds show Einstein's equations were wrong or flawed on this aspect of physics.

Einstein's famous equation, E=mc squared, must not apply to the subatomic world. The 'm' in this equation represents mass, and the scientist at LHC are seeking to deconstruct mass to try and understand what and where mass comes from (the quest for the theoretic Higgs Boson particle). That given, we can replace the 'm' in the equation with an unknown 'x', so E=xc squared. Now comes the problem... if the variable 'x' is a negative value, highly possible when deconstructing a particle, it then represents anti-matter, then E becomes -E, or in other words anti-energy. This anti-energy and anti-matter may very well be what forms theoretical black holes and 'strangelets'... we simply don't know.

The 'Big Bang' theory hypothesizes that this event happened from a singularity, so there is no such thing as a 'small re-creation' of this event. Size and volume are properties of mass, and do not exist in the realm where there is no mass, such as the conditions they are trying to create at LHC. They could quite possibly create the actual 'Big Bang' again, as there is no size to a singularity, therefore there is no size to the re-creation of their 'Big Bang' event.

Steve Hawking is a brilliant man, although he is still a man, and all men make errors. The entire safeguard for the LHC project not producing stable black holes is based around Hawking's theories. Brilliance aside, Hawking's Radiation is still just a theory and not a verifiable fact.

The bottom line is, that these scientists at the LHC DO NOT KNOW what will happen when they try and create their 'miniature re-creation' of the 'Big Bang'. The pursuit of knowledge is not justified when the stakes could possibly be the end of humanity.

I am not a 'doom-monger', nor radical, but one that places great value in the sciences. What concerns me the most is the fact that the scientists involved are not relaying the true facts about LHC, and only expound on science that is only a theory and not fact, this to assure us we will all be OK with their experiments. If they have nothing to hide, then why do they misrepresent the facts?

Woot hooray for the LHC!

In all seriousness, the ramifications of this project (from my own limited research and inferrence) are great. It is also safe to assume that there will be some kind of military use for the technology, considering most, if not all, of the technological advances of the past have been made specifically for military use or then changed to have military use.

Also, I was under the impression that the collider will in fact teach us more about nuclear fusion, which would be an incredible leap in technology.

I'm all for it, although whatever good this does for civilisation will undoubtedly take a back seat to whatever is better for making $$$$!!!!!

At last, someone who makes logical sense out of all this without all the doom and gloom. Thank you for sharing your knowledge!

reply to post by philjwolf


We can and should continue with the experiment but at REDUCED
initial energies which should be stepped up on a gradual basis
and not right at the 5 to 7 Tera-Electron Volts they want to start
with on October 21, 2008.

It's call Test, Study, Wait, Step Up The Energy, Test, Study, Wait,
and test again at a slightly higher energy level so that we can see
the likely "Shock Waves" that precede the "Energy Barrier" before
stepping over into the unknown high-energy abyss of
Unknown Quantum Physics.

It is foolish to dive into a murky river without, at the very
least, testing how deep it is by stepping SLOWLY and SURELY
a little ways in at a time until the comfort zone is reached and
then dive only when one is CONFIDENT that their safety
won't be compromised. In this case...the LHC is diving off
a very high cliff without testing the waters below for sharp rocks.

The LHC physicists, although stating that the risk of something bad
happening is extremely low, IT IS NOT A ZERO percent chance.
And at these energy levels it's like playing Russian Roulette...
we just might shoot ourselves in the head on the VERY FIRST try!

So my suggestion is to start SLOWLY and increase energy levels
at each experiment by a few tens of thousands of electron volts
at a time and in two to three years of the slow but steady climb
in energy levels, mine the LHC data streams for evidence of
preliminary shock waves that indicate we might be nearing
the Energy Wall that will blow us apart if we go past it.

The untold technological riches that could come from
the LHC have been largely unheralded and
TRULY ARE THERE FOR THE TAKING.....BUT.....There IS quicksand
surrounding the treasure which COULD swallow us whole
if we're not careful.

Proceed slowly and carefully is the advice I WANT THEM LHC
PHYSICISTS TO HEED !!!!!!!!

Originally posted by argentus
I'm very interested in the interactions that might be indicative or produce evidence toward gravitational energies being translated into other dimensions. I kind of think of this as akin to higher levels of orbital energies, but not certain that's a proper analogy. What are your thoughts on this aspect of the experiments?

There are two flavours of extra-dimensional theories with regards to particle physics, broadly speaking, "small" and "large". I've read a bit on small extra dimensions, which refer to space-like aspects of the "fabric of reality" that are either closed in themselves, or have intrinsic properties that prohibit any interaction of spatially separated particles. The LHC will be able to study these, if they exist, for the same reason that electron microscopes can achieve higher magnification than light microscopes: Higher energies allow higher resolution. This is a direct corollary of the Uncertainty Principle, among other things.
With regards to large extra dimensions, which as I understand it are the only relevant ones when it comes to gravity, I'm afraid I'm quite out of my depth.

I don't have any fears of micro-singularities, but would also like to know if the theorized situations that might occur to produce strangelets are random, or are steps being taken to avoid formation of them?

It's not possible to take any kind of precautions, as far as I'm aware. High-energy physics is really quite simple - you smash things together and see what happens. Some of the collision products are absorbed by the detector and the rock surrounding the ring, some are not and escape into space. The usual assumption is that anything that can pass through hundreds of metres of rock without interacting will also pass through anything that might suffer from damage (like people), and it's quite a reasonable assumption, if you ask me. Naturally, none of this will be any use if a runaway effect, like those that have been predicted for microscopic black holes and strangelets, occurs. But the same reasoning applies for both: Cosmic rays and other astrophysical phenomena are involved in similar collision all the time, so if any runaway effects were possible, they would have occurred naturally long before now.

Originally posted by Shere Khaan
I guess my point is that currently science's best guess about gravity at the moment is the higg's boson. When they presumably don't find what they are looking for (I'm with Hawkings on this one) they pretty much have to go back to the drawing board.

The Higgs mechanism is the most natural extension of the experimentallly verified parts of the Standard Model. But, as the name suggests, there are plenty of alternative models around, so not finding the Higgs, while a bit of a surprise for most of the community, wouldn't leave anybody stumped. As I said previously, there is the remote possibility that they won't find anything new at all, which would be very annoying because while ruling out several existing models it wouldn't give us any better handle on the multitude of models that aren't ruled out than we have today.


[edit on 11-9-2008 by TeraBlight]

Updates from the newsfeed:

September 10

21.30 at least 300 turns!

September 11

On the menu for today/tomorrow

• Beam 1 beam based measurements, circulating beam
  
• Beam dump commissioning, either beam
  
• RF capture (beam 2 ready)
  
• Consolidation of settings and recycle
  
• Instrumentation commissioning
  

Sounds like no collisions today...

Originally posted by antar
What a great time you must have had working there can you tell us more of your personal experiences?

Personal experiences? Heh, actually the weekends stand out most... I was at CERN for three months during the summer, together with about 200 other physics students from all over the world, and since the region is very beautiful and Geneva has a great nightlife, we pretty much went hiking/mountaineering during the day and clubbing during the night every saturday and sunday. Resulting in waking up monday morning feeling completely knackered and not being able to do much work... thankfully, my supervisor was pretty relaxed about that, as long as I got the work done eventually. Which, in all modesty, I did.
My thesis work itself was done at my university, not at CERN, liaising with the relevant CERN groups once a week by video conference. It had to do with "trigger" software for ATLAS. The detectors produce insane amounts of data, and there is neither a way (technically) nor a need to store most of it, so there are three filtering stages between detector output and data storage. The first runs on dedicated hardware, located close to the detector itself, and throws out about 99% of the collisions, based directly on the raw data. The next runs on normal PCs, does some preliminary reconstruction (meaning, it infers particle trajectories from the raw data, and then particle properties like energy and charge from the trajectories), and throws out again 99% of the remainder. The final stage does full reconstruction of the collision, tentatively identifies particles and throws out everything that doesn't exhibit interesting physics, which is expected to be >99%. So, between one event in a million and one in a billion is expected to be worth storing for analysis leading to new physics, overall.

how did you find us and how long have you been reading the
forum?

I found you via a link to TinWiki in the discussion pages for the LHC articles at Wikipedia, just a few hours before posting this thread.

Originally posted by srsen
Could it be speculated that the Higgs-particle is not actually being created at the moment of impact, but is instead actually simply shifting its dimensional nature, therefore becoming detectable?

Could the Higgs-particle be the result of some kind of dimensional rift which the particle collision and the high energy levels creates?

Well, first off, anything about the "nature" of particles goes really beyond the realm of physics and into metaphysics. One of the things that's tough to accept at first when studying quantum mechanics is that things don't make sense. Most of classical physics, even relativity to an extent, can be quite nicely illustrated with examples from everyday experience that appeal to common sense. QM, on the other hand, cannot be understood in this manner. The mathematical models used, which we know to be valid because they can be used to accurately predict things that are directly observable, simply are so different from those we are intuitively familiar with from living in the macroscopic world that the differences are irreconcilable.
That being said, the current model is indeed rather similar to what you are describing. We imagine that vacuum is filled with a "sea" of virtual particles, which are constantly created out of nothing (out of zero-point energy) and annihilate each other. We call them "virtual" because they don't have enough energy to separate and avoid annihilation. By smashing two protons into each other, we're basically supplying a localized energy boost to this particle sea, which pushes some of them across the barrier that separates virtual from actual particles. The remainder of the energy is carried off by the particles and registers in the detectors.
Again, let me emphasize that this is just a model, and what "really happens" is more of a philosophical question.

Hi,
Just tossing a coin for discussion into this thread.

One man named John Titor called himself a timetraveller from 2036
in a BBS forum in 2000 who said that (in 2000) CERN will do a high energy
experiment shortly that will give a big boost in physics that will eventually
lead to time traveling.

You may find his story in many web pages (google : John Titor)

If his claims of TT is true, this CERN experiment may trigger the tme travel.

carry on with discussions.

Originally posted by son of PC
I don't think that the scientists can destroy the planet, but they could quite easily blow themselves up.

Well, then you need to read more background material. I don't see how there is any chance that LHC might lead to an explosion - again, collision like these happen in the upper atmosphere all the time, and we would have observed those explosions if they took place. Small explosions might happen, I suppose, but since the ring is 100 m underground, this would merely damage the equipment.
The thing that some people claim to be afraid of are runaway effects of a nature that cannot be contained. If this were indeed to happen, it would indeed be a threat to the entire planet (but NOT to the universe, as some threads here seem to claim).

Originally posted by ...and justice for some
do you think that the LHC could start any new weapons like a super nuke or something?

As said in the OP, I'm very certain that LHC has nothing to do with directed weapons research. But, of course, that doesn't mean that the results obtained won't eventually be used to construct weapons. After all, I very much doubt the Curies were thinking about nuclear weapons when they began to investigate radioactivity.
It's important to bear in mind that particle accelerators need to be big, it's physically impossible to scale them down beyond a certain point, no matter what technology is available. So, it won't ever be produce effects like those in LHC using something like a bomb. Deathstar-type weapons would be more feasible.

Originally posted by whatukno
what do you think the next step is going to be? What (if any) data can be extrapolated in the fraction of a second that the particles collide?

The collision itself happens in the vacuum of the beampipe and cannot directly be observed. What is being observed are the collision products, i.e. the particles created in the collision that penetrate the detectors which have been contructed around the collision sites. This data is then preprocessed as described above, stored and investigated at one's leisure.

I had also heard that this machine was also going to be used to create a tiny singularity. (sigh) Any insight into why this singularity will just evaporate instead of grow into a massive black hole and engulf the entirety of the solar system?

If my understanding about singularities is correct, (just based on reading a brief history of time, and a book from his cambridge lectures) which I will admit, I didn't understand completely. Singularities will just evaporate over a given amount of time based on the origional energy put into the singularity instead of grow because of the energy collected from the edge of the event horizon. Is this the case with the singularity proposed to be created at LHC?

Black holes are still hypothetical objects, although the astronomical data that supports that they do indeed exist is piling up lately. The one that I find most convincing, personally, are observations of certain types of accretion disks that occur both around neutron stars and black holes. Accretion disks consist of particles spiralling in towards a central object, and glow because of friction between the particles. The resulting spectrum is completely smooth, as the disk gets hotter the closer the particles get to the center.
In some cases, there is distinct spike superimposed on this smooth spectrum, which without much doubt is the result of the particles impacting on the central object. In other cases, however, there is no such spike. Short of speculating about ways for the particles to vanish entirely, an event horizon (the defining the characteristic of a black hole) is the only good explanation for this.

Microscopic black holes are a lot more speculative, because their creation and behaviour falls into the domain of quantum gravity, for which we have a bunch of (incomplete) theories, none of which have been experimentally confirmed in any way. The idea that LHC might produce such entities is based on a relatively recent version.
Hawking radiation, the mechanism by which black holes may evaporate, is based on the effect the event horizon has on the particle sea mentioned earlier. Basically, it assumes that quantum effects override the "no escape" rule that follows from the relativitic model. The mathematical formulation predicts that the smaller a black hole, the more relevant the quantum effects become, and that a black hole with a mass as low as those produced in an LHC collision would have would shrink much faster by this mechanism than it would grow by attracting matter.

The important aspect is what I stated in the OP, really. We don't really know what will be produced, we don't really know how the things that are produced will behave, but we do know that we're not doing anything that doesn't happen in nature all the time. So, it follows that either no black holes will be produced in the first place, or if they are produced they are short-lived. Catastrophic results can be ruled out a priori (we're still here), not because we understand the physics involved.

[edit on 11-9-2008 by TeraBlight]

Originally posted by antar
Are there people/civilians that live within that 17 mile area inside the ring? And if not how close are domiciles to the experimentation area? I would love to hear if they have strange anomalies happen after this really gets moving and shaking.

Sure, the region is quite densely populated, see map. If any strange effects were to happen, I'd expect them to occur either in proximity to the four collision sites (pretty much the only points at which surface structures tell you that you're currently directly above the ring) or at those places at which the plane in which the ring lies intersects the Earth's surface, which should be roughly 25 km outside the ring. But, as said above, there is no reason to assume that something that can traverse 100 m or even 25 km of rock without effect would have an effect on something on the surface.

Also if we google the coordinates where on earth is the opposite end on the planet? Wonder if they will experience anything out of the norm?

Interesting idea. CERN (zoom in), opposite CERN (zoom out). The bits of land to the north-west are the Chatham Islands, I believe. Someone please find out how deep the sea is there...

Also if they are attempting to discover the billionth second after the big bang, how do they stabilize that affect in order to observe?

They don't. All we can do is try and deduce the conditions at the point and moment of collision from the collision products.

Originally posted by seb2882
I've read somewhere that the next step in the project was going to generate an "enormous energy concentration". Just how much energy would it be, and as a pointer, to what can we compare it to?

Yes, creating an "enormous energy concentration" is not only the next step but the whole point of LHC and all particle accelerators. The energy of a proton-proton collision, as observed by an observer at rest, will be 14 TeV at full power. 1 eV is the energy an electron picks up when it traverses a voltage differential of 1 Volt, and corresponds to about 10^-19 Joules, so 14 TeV correspond to about 10^-6 Joules. The energy needed to lift 1 gram by 1 mm on the Moon, roughly. Or, to use the example everyone seems to be using, about the energy of two mosquitos colliding in flight.
What is enormous is not the energy itself but the energy density, since this amount is squeezed into a space many times smaller than a single atom. Yet another example - it's the energy set free when three heavy atoms and three heavy anti-atoms annihilate, but significantly more focussed than that.

Sorry if this is the wrong place but still its a question, Are there any good feeds still running or a place to get latest updates of whats currently happening, the webcast was great but now thats gone i cant find much

[edit on 11-9-2008 by pazcat]

Originally posted by eaganthorn
Perhaps you could shed some light on the number theories that might be addressed as well as the number and purpose of the various sensors that are installed.

Even an outline would take several pages, and there are many sites that do a much better job at this than I ever could. I suggest Wikipedia as a starting point, as always.

What I can do is give a short overview of how the detectors work. There are 7 in total, the one I was working on is called ATLAS, short for "A Toroidal LHC ApparatuS" (this has got to be the worst reverse acronym ever). The purpose of all of them is, fundamentally, to identify particles. Most of them consist of two principal systems, a "tracker" on the inside and a "calorimeter" on the outside. The tracker is used to map out the trajectory of a particle, usually by means of silicon chips, in which the particles cause an electrical signal (similar to solar cells or CCD chips in digital cameras), and/or chambers filled with a substance that scintillates when traversed by relativistic particles (as mentioned earlier, this can be done with a human eyeball, if one is so inclined). Since a magnetic field is applied across the detector, charged particles give curved trajectories. The calorimeter consists simply of big blocks, which ideally absorb the particle's entire energy. One of the main challenges in designing a detector is that it needs to be able to reset very quickly, as the collision occur very rapidly.

Originally posted by glad_to_be_His
I'm just wondering if the higher-energy factor that occurs in nature isn't the very thing that protects us from the disaster? Is that possible?

Not at all, cosmic rays occur at all energies, and there are many more in the TeV-range (LHC energies) than in the 10^18 eV range (a million times LHC energies). (Graph)
The reason I mentioned the higher-energy ones was just to emphasize that not only is LHC not doing anything unusual, but it's not even close to the most extreme cases that occur in nature. Sorry if that was unclear.

Originally posted by Yarcofin
Why are multiple governments pooling together 6 billion dollars to make this machine to study particle collision? What use is it? What technologies or applicable groundbreaking discoveries will come out of this project?

Why is this project a better descision than, say, spending 6 billion on alternative energy (unless this experiment will contribute advanced knowledge of nuclear fission/fusion) or medicine?

There is no easy answers to that. From personal experience, most physicists do physics for the same reason as artists do art - for its own sake. Humans are curious by design, and science is one of the purest expressions of this curiosity. In a way, it's the basis for civilization itself.
Other than that, justifying the benefits of pure as opposed to applied science is always a difficult task. One of the arguments used most often is the historical analogy - the likes of Newton and Maxwell didn't live to see any direct benefit for mankind come from any of their discoveries. And, I daresay, they couldn't have cared less. They were scientists, not inventors or engineers. Yet, without their work, pretty much none of the scientific progress made during the twentieth century would have been possible. The same thing may well turn out to be the case for any discoveries made at LHC - we might not live to see any technological progress based upon it, but in one or two hundred years these might prove all the more pivotal.

Thanks to the OP for creating this excellent thread!

I also found this cool and also quite educational rap video at YouTube, and thought this was the best place to post it. (Forgive me if it has been posted before here at ATS, I am having trouble with the search function at the moment. I keep getting error messages.)

Large Hadron Rap

However, as has been stated many times, nothing that happens at LHC doesn't happen in nature (in space) all the time, and at yet much higher energies (typical ultra-high-energy cosmic rays are a million times as energetic as LHC protons). The reason for recreating these events in a controlled fashion is simply to enable us to put the detector in the right place. So, all reason suggests that if something catastrophic could occur, it would have occured naturally long before now.

You stated the above, so can you please explain to me when in nature on earth have these particles smashed into each other at such high speeds,
And if it does happen like you say, then does that mean mini black holes are popping up in front of our eyes all the time, but so fast we dont see them.

Also if it is true what you say then what is the force that shoots the particles around us at such high speed without the use of an LHC macine.

You also say that if something catastrohpic could occur, it would have done naturally before now, Why? in nature something could happen but nature may have a counterbalance to correct it. so you are creating something that you say happens naturally in nature, does this mean you know the counterbalance to correct it if anything goes wrong, as nature may do.

Do not forget you have these things sealed, they are not in open air as in nature where a natural element may be to counterbalance any bad effect.

I hope I have explained enough for you to see where I am coming at.

Maybe I dont fully understand the LHC, but I saw your statement above and had to ask.

Originally posted by qonone
Do you know what could happen if the machine (tunnel pipeline) breaks on collision impact? The unknown particles should enter the surrounding atmosphere, not?

"Breaks" is the wrong word, the beam would simply penetrate the pipe-wall, burning a hole into it in the process. It would then enter the surrounding rock, where it would create a particle cascade no different from the one that will regularly occur when the beam is "dumped" onto the targets that are made just for this purpose. So, the only significant consequence would be minor equipment damage, it would pretty much be the most benign malfunction imaginable.

Originally posted by oatie
If the cooling system failed it would be catastrophic. the magnets would explode and pretty much destroy the 5.8 billion dollar experiment.

I don't think so. The system should have enough thermal inertia that even a complete, system-wide cooling failure would not depolarize the magnets quickly enough to prevent them from dumping the beam before it gets out of control. A microsecond is all that's needed. But, as I'm not a techinician, this is just my best guess.

Originally posted by noobfun
and as for the mini blackholes calculations showed that if they were created only 1 in 10 or 100 ish would get trapped by the earth and they would be so small they could actually travel through the empty space in solid objects and on the rare occasions they actual do collide it would take years for them to eat a single proton and exahust thm selves long before the millions of years they would take to start causing problems for anything bigger then stray particles

I dunno, the basic physics in Roessler's (the guy who launched the European court case against LHC) pa per seem sound enough to me. It's conceivable that microscopic black holes would be created, it's conceivable they wouldn't evaporate, it's conceivable they would attract matter electromagnetically by a quasar-like mechanism, and it's conceivable that this would lead to exponential growth. The point is that since we know so little about what to expect, being conceivable applies to a lot of scenarios. What we know is that whatever happens won't be catastrophic, because... well, I think I made the point often enough now.

Originally posted by qonone
I am just thinking if (a big if) at collision in October the machine cracks or break. Those "unknown" particles they are searching for should surely enter our atmosphere and seeing it is unknown no one can truly be sure what would happen. Sure they have a back up, well i hope.

There are two types of particles that are produced, strongly and weakly interacting ones. Irrespective of whether there is a malfunction or not, neither will be a problem. The strongly interacting ones are meant to be absorbed by the detector, but if they aren't, they'll be absorbed by the rock instead. The weakly interacting ones will indeed escape, but since they are weakly interacting, this is not a problem, they don't interact with human tissue any more than they do with rock. That's part of the reason why they build these things underground.

[edit on 11-9-2008 by TeraBlight]

Originally posted by pazcat
Are there any good feeds still running or a place to get latest updates of whats currently happening, the webcast was great but now thats gone i cant find much

The best thing I can find is the feed I linked earlier.

If I understand their jargon correctly, it's basically saying that they successfully finished calibrating the machine for continuous clockwise operation, and will do the same thing for counterclockwise operation tonight. Once this is accomplished, they will be able to inject both beams simultaneously and circulate them indefinitely. Which means we can expect first collisions tomorrow morning (low energies and low rates, though). If they stick with injection energies and don't apply an RF boost, which I think is the plan, this will still be well below previously established levels.

reply to post by TeraBlight


From TeraBlight:

"However, as has been stated many times, nothing that happens at LHC doesn't happen in nature (in space) all the time, and at yet much higher energies (typical ultra-high-energy cosmic rays are a million times as energetic as LHC protons). "

_____________________________________

Let us say that this is true. But where in nature is there seen high energy cosmic rays focused in a tight oscillating super cunducting magnetically bound beam where it is sent smashing in 180% fashion into another beam of equivalent speed and focus. My point is this, Sunlight is harmless unless using a mgnifying glass. Light is harmless unless focused into a lasar beam.

Secondly, is there even the slightest possibility of CERN making a black hole, and if so, is there a possibility that it could receive enough mass to grow if that mass is at the event horizon. What I mean by this is, if the mini black hole is in the Earth, the Earth would constantly feed the hole over the event horizon would it not?

Thankyou for your imput.

Starred.. thank you for bringing sanity to the boards.

In the special I saw on the history channel about the LHC, the scientists seem quite unconcerned about major issues. They were being very cautious in regards to the issues they really feel they could have, but have practiced the shutdowns extensively above-ground, before the bits were even put into the tunnel.