I'm very familiar with the scientific model, which is why they are running experiments at the LHC rather than just announcing supersymmetry as fact.
However, the scientific model doesn't tell you what experiments to run, or what theories to form or test. Scientists have to decide what they think "needs" an explanation, then they can look around for an explanation which fits the existing data and devise experiments to acquire new data to test it. If the new data fits the theory well enough the theory becomes part of our model of the universe, which is now a little more complete and precise. If it doesn't they try again. The last part is what is usually called "scientific method" but it doesn't help you decide what to try and explain, or which explanations to test first.
In this case, physicists, backed by decades of experience have identified the low mass of the Higgs boson (relative to the Planck mass, as it happens) as the kind of thing that might be expected to have an explanation (beyond just "that's how the universe is") so they have looked around for such an explanation. There are a few competing ones, of which supersymmetry is the best worked out. Actually supersymmetry is not just one theory, it has many variations, The new LHC run may support or exclude some or all of these.
Pretty much what it says. The theory that relates all the existing particles ("The standard model") doesn't predict a mass for the Higgs boson, it's a number you have to measure and put into the theory. The theory does suggest limits -- it can't be less than zero or more than about a million million million times what it is. So it's a bit like finding something that could in principle be anywhere on a line from New York to San Fransisco but happens to be less than one atomic diameter from the New York end of the line. It could be chance but it doesn't feel right. That "not feeling right" is what I mean by unaesthetic.
Experience in physics is that things that "don't feel right' in this way usually hint at a deeper explanation which we don't understand. This one might not, but it seems worth looking.
One goal is to better understand the properties of the HIggs boson by making lot more of them. This will surely happen. There are a bunch of similar things where they just want more data to get details of something already discovered.
After that, the biggest target is supersymmetry. This is a purely theoretical notion (at present) which would offer a nice explanation for one of the major mysteries of current particle physics -- why particles like the Higgs are as light as they are. At the moment we have a bunch of equally "natural" theories in which Higgs masses range from little or nothing to massively more than they are now. Hitting a value this close to zero by chance is unaesthetic and experience suggests that when something like this happens there is usually a deeper explanation. Supersymmetry is a candidate for such an explanation.It would predict a whole slew of new particles, the lightest of which might be stable and might be within reach of the new LHC. They also might make up some or all of the "dark matter" which seems to make up most of the Universe.
The dark matter is also a target in its own right. Even if it isn't made of supersymmetry particles, it might be made of some other kind of particle light enough for the LHC to make some.
Then there are more exotic conjectures around like extra dimensions and dark energy particles wjich might show up.
You are right that the no moving parts thing is speculation, but it's what I'd do. Several people have worried about disk failures and such like as a concern with the idea, and noise would also be a concern.
Regarding cabling, yes, you are right. In densely populated areas of the Netherlands there is probably fibre to the apartment building already, but they might have a low-networking workload in mind.
Simulations suggest that it is very sensitive to exactly where the gas giants form and the density of different parts of the dust cloud. Small changes in initial conditions mean that they may head in and stay there -- hot Jupiters; never head in at all -- hot super-Earths; or do what ours did and dive in and then out.
1. Thermodynamics: if you need to convert electricity to heat for any purpose you can get computation out for free. Electricity is very low entropy, low-grade heat over a large area very high, you can have the difference as useful computation
2. The article makes clear these are compute servers, not data servers or web servers. They may well be bitcoin mining, or running large-scale compute jobs for universities or the local met office or rendering a movie or... In any event you expect a proportion of the servers in any job to fail. When you think they may have failed you restart the tasks they were doing somewhere else. Most of these tasks do not need much security either. There is little to gain by stealing or changing the predicted air pressure in a 100x100x10km block of air over Belgium next Thursday.
3. They are surely custom servers, not standard racks -- no moving parts. SSD for boot, application data over the net and a fanless design. They can be totlally sealed units entirely immune to junior's orange juice. Use mainly nonstandard form factors and they become basically unsellable reducing the theft problem and getting round some more security issues.
3. The article says that the supplier supplies power. Whatever cable they use for that can easily have a fibre built in for data.
4. Since this is cloud compute, it doesn't matter much if it gets turned off on rare hot days in the Netherlands, but if you care, pay the owner to open a window instead.
Have we any reason to think the water was actually ever liquid on Mars's surface to any great extent. The young sun would have been cooler than todays. Could the water not have been present as ice, or perhaps as an ocean covered by a thick layer of ice.
I think the idea is this: You have a large volume of clathrates underneath ice or frozen soil. As things warm, they start to break down and a reservoir of methane gas builds up at high pressure. Eventually the pressure reaches the point where it can push aside or lift up or whatever the ice at its weakest point and it finds a route to the surface.
Now you have a LOT of gas rushing through some kind of hole, a little bit like an oil well blowout and the gas flow erodes the sides of the hole and throws soil or ice into the air and generally starts to make a crater.
Furthermore the escape of all this gas lowers the pressure down where the clathrates are quite suddenly, so the breakdown accelerated greatly, providing still more gas to ruch up through the hole.
So not really an explosion, perhaps more like a blowout, but still fairly violent simply because of the amount of gas and the pressure.
You need to find out about methane clathrates. They are very roughly a chemical compound of methane and water which is solid and stable at low temperatures and moderately high pressures (as found under a few hundred meters of water or ice, for instance. When they get a bit too warm, or the pressure drops a bit they turn back into methane gas and water. One cubic meter of clathrate released almost 200 cubic meters of methane gas, which then has to go somewhere producing something like an explosion. At no point did the methane burn (it was nowhere near any free oxygen until it got to the surface, it was just a gas pressure explosion.
Know is a tricky word, but there is plenty of evidence that most of the dark matter is not baryonic. The proportions of light elements formed at the end of the big bang gives a contstaint on the baryon density of the universe at the time, as do the ripples in the cosmic microwave background (which reveal the balance between radiation pressure and gravity in the early universe and tell us that most of the mass did not interact with photons at all). The bullet cluster is another piece of evidence. The stars in the colliding galaxies interacted with one another and with dust and merged into one bigger galaxy, but something, detectable by its gravitational lensing of galaxies beyond it, went straight through. It's hard to see how brown dwarves would have done that.
As I recall the best choice for a low-mass sunshield is a grid of fine conductive wires about 100nm or so apart in both directions. This forms a Faraday cage at optical frequencies. There's a complicated tradeoff between what you make the wires out of, how much is reflected and how much absorbed and how fine you can make the wires without them melting. I'm not sure what the winner is for this application, but the area density of such a material can be less than that of a carbon monolayer, since it's mostly holes, just holes too small for light to get through.
You can probably keep it on station without rockets by opening and closing flaps in the sail to manage light and solar wind pressure, although the control processing might be pretty severe.
You can use similar techniques to terraform Venus and Mars -- for Mars you make the "shield" into a Fresnel lens that actually concentrates sunlight.
I seem to recall third, but the stars that make and scatter medium-weight elements are big bright short-lived ones, so the first generation might only have taken 10 million years. There is some uncertainty about where the heavier elements (gold, uranium, etc.) come from. It is possible they are produced by a much rarer process.
You talk about ""science" --- the one with hypothesis, testing, reproduction of results". These things do kind of apply to cosmology. Hypothese are about things like the statistical distribution of galaxy sizes and redshifts, or the exact spectrum of the cosmic microwave background or the proportions of elements in the oldest stars or... The speculators are working out these prediction so that the observational astronomers can test them with their next set of instruments. Or in some of the other areas, about what we will see in the LHC when we reproduce on a very small scale certain conditions.
Reproduction of results is harder, because we only have one universe, but people only become convinced of an explanation when there are multiple chains of evidence supporting it. So dark matter is supported by galaxy rotation, features of the cosmic microwave background spectra, gravitational lensing AND siumulations of galaxy distribution.
creating a spark that lasts seconds and outputs more energy than the sun has in the past million years.
Actually it lasts only about a millisecond, but the 1 MYears of solar output part is right. It's about the mass of the moon converted to RF energy in 1 ms.
Constant approaching velocity is special relativity again, and again the velocities don't add the way you expect.If the planets in your example are approaching at 2/3 c they each see the other approaching at 12/13 c and they will very definitely and messily interact. Each exists for the other.
In this case acceleration makes no essential difference though. In either planets frame of reference there is an event horizon behind it (in GR acceleration and gravity are equivalent) but none in front of it, so they can see each other and interact freely.
If you're dealing with constant velocities, you are in the territory of special relativity. In this world there are no event horizons and every object can interact with every other. If two galaxies are each receding in opposite directions from a third central one at 2/3 c they will each see the other receding at 12/13 c according to https://en.wikipedia.org/wiki/... (section 2). Velocities do not add up the way you think they do and when they get to a decent proportion of light speed it starts to matter. This has been experimentally checked using moving atomic clocks. Thus they can keep on exchanging messages, although the messages will be quite redshifted when they arrive and take longer and longer to make the journey.
However, the original article deals with accelerating motions, since that is what the universe seems to be doing. This is crucial.
One way of seeing what happens is to imagine two galaxies accelerating away from one another. Assume there are clocks freely falling in both galaxies. Define a function f so that a signal sent from one galaxy at lightspeed (could be photons, gravitons, neutrinos, doesn't matter) at time t on the local clock arrives at the other galaxy at time f(t) on its local clock. It's not hard (for anyone with a degree in astrophysics) to work out exactly what function f is. It turns out that there is critical time T such that as t approaches t from below, f(t) approaches positive infinity. In other words the last few signals emitted by one galaxy as it's clock ticks towards T are spread out across the whole of the rest of time when they finally catch the other galaxy and no signal emitted at or after time T can ever arrive. The critical time T depends on the current separation, velocity and acceleration of the galaxies in a fairly straightforward way. After local time T nothing you do can affect the other galaxy. After its time T you can never find out what happened to it.
Could do, although there is no evidence of such an effect up to now. The laws of physics could also just change tomorrow for no particular reason, in thi sarea, or in some much more down-to-earth one, like whether the proton is stable. We can never know.
The article is essentially in the business of explaining the consequences of the laws as we currently conjecture them to be (which fit what we can observe pretty well). It can't make any stronger claim to be "correct" than that, but, apart from refining "pretty well" to "very well" nor can any physical theory.
To get very far away from us they started receding from us at a higher speed than objects that are closer. However, nobody can point to where an object "disappeared" - it's all conjecture unsupported by experiment or direct observation. Who knows, maybe when the fabric of the universe gets too thin, the repulsive force becomes an attractive force. We simply don't know enough yet.
Of course. Anything could happen, but there is a remarkably consistent, and mathematically simple, if somewhat unintuitive picture emerging of how the universe has evolved on the largest scales. The picture in general (dark matter, dark energy, etc,) is consistent with a number of independent sets of data, for example supernova surveys and detailed analysis of the cosmic microwave background. The article is trying to explain the consequences of this picture.
What we can see are galaxies at very high redshifts and evidence for accelerating expansion. If the dark energy explanation for the expansion is right, then lighjt emitted from those galaxies (which we can see) a few billion years after the light we see them by now, will never reach us. Of course some unknown thing could intervene to prevent this happening, but we see no sign of such a thing yet.
If B and C are close enough to be gravitationally bound then A will lose contact with both of them at the same time.
Objects don't have to be gravitationally bound to influence each other. A rogue plantoid passing through our system isn't gravitationally bound to it, but our gravity still can modify its path.
You're right, but you've misunderstood my point. If A, B and C are all "far" apart then all the distances are increasing at an accelerating velocity and the situation is as I described it. The last paragraph deals with the special case where B and C are close enough that they are not accelerating apart. In this case B and C will remain in contact forever, and so A will lose touch with both of them at the same time.
Doesn't work. If you try and relay light (or any other message) along the line from the distant galaxy to us, what happens is that it reaches each relay station just as the relay station loses contact with us. It never arrives.
Can there still be interaction between the galaxy that just disappeared, and a galaxy mid-way between us? Yes.
Can there still be interaction between the middling galaxy and us? Yes..
Both true, but these interactions don't combine. Suppose you have three galaxies in a line A--- B---C and A and C are just leaving causal contact. Suppose a light-speed message is sent from A towards B and C. B will indeed receive it, and be able to reply to it (maybe) but that will happen just as B and C leave causal contact (the universe having carried on expanding), so that if that message is forwarded towards C it will still not arrive. The photons in the forwarded message cannot overtake those in the original message that are still flying from B towards C.
If B and C are close enough to be gravitationally bound then A will lose contact with both of them at the same time.
Slashdot Mirror
I'm very familiar with the scientific model, which is why they are running experiments at the LHC rather than just announcing supersymmetry as fact.
However, the scientific model doesn't tell you what experiments to run, or what theories to form or test. Scientists have to decide what they think "needs" an explanation, then they can look around for an explanation which fits the existing data and devise experiments to acquire new data to test it. If the new data fits the theory well enough the theory becomes part of our model of the universe, which is now a little more complete and precise. If it doesn't they try again. The last part is what is usually called "scientific method" but it doesn't help you decide what to try and explain, or which explanations to test first.
In this case, physicists, backed by decades of experience have identified the low mass of the Higgs boson (relative to the Planck mass, as it happens) as the kind of thing that might be expected to have an explanation (beyond just "that's how the universe is") so they have looked around for such an explanation. There are a few competing ones, of which supersymmetry is the best worked out. Actually supersymmetry is not just one theory, it has many variations, The new LHC run may support or exclude some or all of these.
Wat do u mean unaesthetic.
Pretty much what it says. The theory that relates all the existing particles ("The standard model") doesn't predict a mass for the Higgs boson, it's a number you have to measure and put into the theory. The theory does suggest limits -- it can't be less than zero or more than about a million million million times what it is. So it's a bit like finding something that could in principle be anywhere on a line from New York to San Fransisco but happens to be less than one atomic diameter from the New York end of the line. It could be chance but it doesn't feel right. That "not feeling right" is what I mean by unaesthetic.
Experience in physics is that things that "don't feel right' in this way usually hint at a deeper explanation which we don't understand. This one might not, but it seems worth looking.
One goal is to better understand the properties of the HIggs boson by making lot more of them. This will surely happen. There are a bunch of similar things where they just want more data to get details of something already discovered.
After that, the biggest target is supersymmetry. This is a purely theoretical notion (at present) which would offer a nice explanation for one of the major mysteries of current particle physics -- why particles like the Higgs are as light as they are. At the moment we have a bunch of equally "natural" theories in which Higgs masses range from little or nothing to massively more than they are now. Hitting a value this close to zero by chance is unaesthetic and experience suggests that when something like this happens there is usually a deeper explanation. Supersymmetry is a candidate for such an explanation.It would predict a whole slew of new particles, the lightest of which might be stable and might be within reach of the new LHC. They also might make up some or all of the "dark matter" which seems to make up most of the Universe.
The dark matter is also a target in its own right. Even if it isn't made of supersymmetry particles, it might be made of some other kind of particle light enough for the LHC to make some.
Then there are more exotic conjectures around like extra dimensions and dark energy particles wjich might show up.
You are right that the no moving parts thing is speculation, but it's what I'd do. Several people have worried about disk failures and such like as a concern with the idea, and noise would also be a concern.
Regarding cabling, yes, you are right. In densely populated areas of the Netherlands there is probably fibre to the apartment building already, but they might have a low-networking workload in mind.
Simulations suggest that it is very sensitive to exactly where the gas giants form and the density of different parts of the dust cloud. Small changes in initial conditions mean that they may head in and stay there -- hot Jupiters; never head in at all -- hot super-Earths; or do what ours did and dive in and then out.
1. Thermodynamics: if you need to convert electricity to heat for any purpose you can get computation out for free. Electricity is very low entropy, low-grade heat over a large area very high, you can have the difference as useful computation
2. The article makes clear these are compute servers, not data servers or web servers. They may well be bitcoin mining, or running large-scale compute jobs for universities or the local met office or rendering a movie or ... In any event you expect a proportion of the servers in any job to fail. When you think they may have failed you restart the tasks they were doing somewhere else. Most of these tasks do not need much security either. There is little to gain by stealing or changing the predicted air pressure in a 100x100x10km block of air over Belgium next Thursday.
3. They are surely custom servers, not standard racks -- no moving parts. SSD for boot, application data over the net and a fanless design. They can be totlally sealed units entirely immune to junior's orange juice. Use mainly nonstandard form factors and they become basically unsellable reducing the theft problem and getting round some more security issues.
3. The article says that the supplier supplies power. Whatever cable they use for that can easily have a fibre built in for data.
4. Since this is cloud compute, it doesn't matter much if it gets turned off on rare hot days in the Netherlands, but if you care, pay the owner to open a window instead.
Have we any reason to think the water was actually ever liquid on Mars's surface to any great extent.
The young sun would have been cooler than todays. Could the water not have been present as ice, or perhaps as an ocean covered by a thick layer of ice.
I think the idea is this:
You have a large volume of clathrates underneath ice or frozen soil.
As things warm, they start to break down and a reservoir of methane gas builds up
at high pressure.
Eventually the pressure reaches the point where it can push aside or lift up or whatever the ice at its weakest point
and it finds a route to the surface.
Now you have a LOT of gas rushing through some kind of hole, a little bit like an oil well blowout and the gas flow erodes the sides of the hole and throws soil or ice into the air and generally starts to make a crater.
Furthermore the escape of all this gas lowers the pressure down where the clathrates are quite suddenly, so the breakdown accelerated greatly, providing still more gas to ruch up through the hole.
So not really an explosion, perhaps more like a blowout, but still fairly violent simply because of the amount of gas and the pressure.
At no point does it combust.
You need to find out about methane clathrates. They are very roughly a chemical compound of methane and water which is solid and stable at low temperatures and moderately high pressures (as found under a few hundred meters of water or ice, for instance. When they get a bit too warm, or the pressure drops a bit they turn back into methane gas and water. One cubic meter of clathrate released almost 200 cubic meters of methane gas, which then has to go somewhere producing something like an explosion. At no point did the methane burn (it was nowhere near any free oxygen until it got to the surface, it was just a gas pressure explosion.
This approach to government canbe seen working well in Somalia.
OK. I stand corrected.
Know is a tricky word, but there is plenty of evidence that most of the dark matter is not baryonic. The proportions of light elements formed at the end of the big bang gives a contstaint on the baryon density of the universe at the time, as do the ripples in the cosmic microwave background (which reveal the balance between radiation pressure and gravity in the early universe and tell us that most of the mass did not interact with photons at all). The bullet cluster is another piece of evidence. The stars in the colliding galaxies interacted with one another and with dust and merged into one bigger galaxy, but something, detectable by its gravitational lensing of galaxies beyond it, went straight through. It's hard to see how brown dwarves would have done that.
As I recall the best choice for a low-mass sunshield is a grid of fine conductive wires about 100nm or so apart in both directions. This forms a Faraday cage at optical frequencies. There's a complicated tradeoff between what you make the wires out of, how much is reflected and how much absorbed and how fine you can make the wires without them melting. I'm not sure what the winner is for this application, but the area density of such a material can be less than that of a carbon monolayer, since it's mostly holes, just holes too small for light to get through.
You can probably keep it on station without rockets by opening and closing flaps in the sail to manage light and solar wind pressure, although the control processing might be pretty severe.
You can use similar techniques to terraform Venus and Mars -- for Mars you make the "shield" into a Fresnel lens that actually concentrates sunlight.
I seem to recall third, but the stars that make and scatter medium-weight elements are big bright short-lived ones, so the first generation might only have taken 10 million years. There is some uncertainty about where the heavier elements (gold, uranium, etc.) come from. It is possible they are produced by a much rarer process.
You don't get relatavistic velocities with fission or fusion propulsion at reasonable mass ratios. You need antimatter for that.
You talk about ""science" --- the one with hypothesis, testing, reproduction of results". These things do kind of apply to cosmology. Hypothese are about things like the statistical distribution of galaxy sizes and redshifts, or the exact spectrum of the cosmic microwave background or the proportions of elements in the oldest stars or ... The speculators are working out these prediction so that the observational astronomers can test them with their next set of instruments. Or in some of the other areas, about what we will see in the LHC when we reproduce on a very small scale certain conditions.
Reproduction of results is harder, because we only have one universe, but people only become convinced of an explanation when there are multiple chains of evidence supporting it. So dark matter is supported by galaxy rotation, features of the cosmic microwave background spectra, gravitational lensing AND siumulations of galaxy distribution.
creating a spark that lasts seconds and outputs more energy than the sun has in the past million years.
Actually it lasts only about a millisecond, but the 1 MYears of solar output part is right. It's about the mass of the moon converted to RF energy in
1 ms.
Constant approaching velocity is special relativity again, and again the velocities don't add the way you expect.If the planets in your example are approaching at 2/3 c they each see the other approaching at 12/13 c and they will very definitely and messily interact. Each exists for the other.
In this case acceleration makes no essential difference though. In either planets frame of reference there is an event horizon behind it (in GR acceleration and gravity are equivalent) but none in front of it, so they can see each other and interact freely.
If you're dealing with constant velocities, you are in the territory of special relativity. In this world there are no event horizons and every object can interact with every other. If two galaxies are each receding in opposite directions from a third central one at 2/3 c they will each see the other receding at 12/13 c according to https://en.wikipedia.org/wiki/... (section 2). Velocities do not add up the way you think they do and when they get to a decent proportion of light speed it starts to matter. This has been experimentally checked using moving atomic clocks. Thus they can keep on exchanging messages, although the messages will be quite redshifted when they arrive and take longer and longer to make the journey.
However, the original article deals with accelerating motions, since that is what the universe seems to be doing. This is crucial.
One way of seeing what happens is to imagine two galaxies accelerating away from one another. Assume there are clocks freely falling in both galaxies.
Define a function f so that a signal sent from one galaxy at lightspeed (could be photons, gravitons, neutrinos, doesn't matter) at time t on the local clock arrives at the other galaxy at time f(t) on its local clock. It's not hard (for anyone with a degree in astrophysics) to work out exactly what function f is. It turns out that there is critical time T such that as t approaches t from below, f(t) approaches positive infinity. In other words the last few signals emitted by one galaxy as it's clock ticks towards T are spread out across the whole of the rest of time when they finally catch the other galaxy and no signal emitted at or after time T can ever arrive. The critical time T depends on the current separation, velocity and acceleration of the galaxies in a fairly straightforward way. After local time T nothing you do can affect the other galaxy. After its time T you can never find out what happened to it.
Could do, although there is no evidence of such an effect up to now. The laws of physics could also just change tomorrow for no particular reason, in thi sarea, or in some much more down-to-earth one, like whether the proton is stable. We can never know.
The article is essentially in the business of explaining the consequences of the laws as we currently conjecture them to be (which fit what we can observe pretty well). It can't make any stronger claim to be "correct" than that, but, apart from refining "pretty well" to "very well" nor can any physical theory.
To get very far away from us they started receding from us at a higher speed than objects that are closer. However, nobody can point to where an object "disappeared" - it's all conjecture unsupported by experiment or direct observation. Who knows, maybe when the fabric of the universe gets too thin, the repulsive force becomes an attractive force. We simply don't know enough yet.
Of course. Anything could happen, but there is a remarkably consistent, and mathematically simple, if somewhat unintuitive picture emerging of how the universe has evolved on the largest scales. The picture in general (dark matter, dark energy, etc,) is consistent with a number of independent sets of data, for example supernova surveys and detailed analysis of the cosmic microwave background. The article is trying to explain the consequences of this picture.
What we can see are galaxies at very high redshifts and evidence for accelerating expansion. If the dark energy explanation for the expansion is right, then lighjt emitted from those galaxies (which we can see) a few billion years after the light we see them by now, will never reach us. Of course some unknown thing could intervene to prevent this happening, but we see no sign of such a thing yet.
What sort of proof do you want, and how does gravity come into it? Happy to try.
If B and C are close enough to be gravitationally bound then A will lose contact with both of them at the same time.
Objects don't have to be gravitationally bound to influence each other. A rogue plantoid passing through our system isn't gravitationally bound to it, but our gravity still can modify its path.
You're right, but you've misunderstood my point. If A, B and C are all "far" apart then all the distances are increasing at an accelerating velocity and the situation is as I described it. The last paragraph deals with the special case where B and C are close enough that they are not accelerating apart. In this case B and C will remain in contact forever, and so A will lose touch with both of them at the same time.
Doesn't work. If you try and relay light (or any other message) along the line from the distant galaxy to us, what happens is that it reaches each relay station just as the relay station loses contact with us. It never arrives.
Can there still be interaction between the galaxy that just disappeared, and a galaxy mid-way between us? Yes.
Can there still be interaction between the middling galaxy and us? Yes..
Both true, but these interactions don't combine. Suppose you have three galaxies in a line A--- B---C and A and C are just leaving causal contact.
Suppose a light-speed message is sent from A towards B and C. B will indeed receive it, and be able to reply to it (maybe) but that will happen just as B and C leave causal contact (the universe having carried on expanding), so that if that message is forwarded towards C it will still not arrive. The photons in the forwarded message cannot overtake those in the original message that are still flying from B towards C.
If B and C are close enough to be gravitationally bound then A will lose contact with both of them at the same time.