But as a scientist you do need to trust. You can't do everything from scratch and need to make use of previous results. If you are doing an experiment with X-rays, you may need to trust someone else's instrument on the spectrum of the X-rays that are hitting your sample. You may not have prepared the sample yourself but need to trust whoever did to have done so correctly. You may rely on someone else's detectors to see the results of the experiment.
To some extent you can cross check the most difficult / risky parts of the experiment, but you can't cross-check everything withing a reasonable time and money budget.
We use matlab extensively at SLAC. If the license fee isn't a problem, it is a very powerful language for numerical work. The language includes a variety of high performance toolkits with multi-processor, distributed computing and GPU support.
OCTAVE and the other free versions really do not substitute for matlab - I'd recommend python instead if matlab is too expensive.
I've used python as well, and it is OK, but IMHO less optimized in structure for numerical work (even with pylab etc) than matlab, but better for other types of programming.
Because if they weren't paid, some of them would become unhappy and find other work. The cost of replacing those people could easily exceed the cost of paying for the furlough. I'm fortunate to work for a contractor (SLAC) so I wasn't furloughed, though it would have happened if the shutdown had gone on much longer. If I had been furloughed and didn't get back pay I might have been annoyed enough to see what other options are out there. I could certainly be replaced but I expect that the disruption to ongoing projects would make it more expensive that just paying me for that time.
Other organization are free to do as they want. I wonder if local coffee shops laid off workers because of reduced short term demand? I suspect that most would have kept them on to avoid the cost / risk of hiring someone new.
I think that electric vs. hybrid depends on your use pattern. If your typical use is a commute that is within the vehicle range, and you either rarely take long trips, or you have a second car, then pure electric may make sense. If you frequently need to drive beyond the recharge range of a pure electric, then a hybrid makes sense.
In my case the 30 mile range would work out OK. That would let me do my daily commute all on electric, but I would have the gas engine for long trips.
I don't personally want the sort of car the Cadillac builds, but I can see the appeal to some people. If most of your driving is 20mph in rush-hour traffic, a high performance sedan may provide no benefit at all, but soft seats, good sound system etc may make things more pleasant if you can afford them.
Whether pure-electric or hybrid is a win on CO2 likely depends on the energy mix in the area where you are charging the car. It also depends on how you measure: average energy mix or marginal energy mix? Then there are of course energy costs for the fabrication of the car, batteries etc. Overall though both approaches are quite good. The only influence I'd like to see the government apply to this is through taxes on energy sources, not specific taxes ore rebates on specific technology choices.
Many (all?) of the labs are contracted by the the government through other organizations. For example SLAC where I work is administered by Stanford University under contract with the Department of Energy. We are not shut down yet, but presumably will be soon if the government shutdown continues. We are under various restrictions to only do critical work, so, for example, the SLAC Today publication that reports on our work is not operating.
The lack of neutrons in this reactions is nice, but the protons and boron nuclei still need to overcome the Coulombe barrier. Generating practical fusion power still needs a combination of pressure, temperatures and containment times that have not yet been achieved in fusion machines. Accelerator base fusion works (for p-B, or hydrogen, but too many of the particles scatter rather than reacting so you can't reach break even.
This scheme sounds nice for R&D, but not at all clear that it can lead to break-even
Companies want to sell their products at the highest price each consumer will pay. By charging large fees for convenience items they are able to extract more money from people who place a higher value on their own time.
So, you could save money getting a SIM card for your phone to use internationally, but that would take time and make it more difficult for people to contact you. You could go to the hotel lobby for internet, but using the internet in your hotel room saves time.
This has the perverse effect that it may make sense for companies to spend extra money to waste your time or to provide worse service, if it pushes you to one of their higher priced services - assuming of course that they don't push you to a competitor.
Its just one of the very annoying effects of the free market. If you want to feel good about it, think if it as a "tax" on the wealthy who are able to put a higher value on their own time.
I've personally observed a standard digital camera interfere with the navigation radio on my Bonanza, and I've seen a flawed TURNED OFF emergency locator beacon interfere with GPS (the antenna was receiving a signal from a communication radio and the output diodes up-converted the signal into the GPS band and then this interference was re-transmitted.
I'm glad they are reducing the restrictions, but it was definitely worth studying carefully before they did so. It is NOT obvious that there is not a problem.
Were all the expenses already paid for? I've gone to a couple of conferences a year for the past 20 years and I've never been to one where there were not significant expenses that were charged at the time of the conference and reimbursed later. I'm in physics so maybe things are run very differently.
There is a real desire to save money in every way possible to delay when more people need to be furloughed. Relatively small expenses add up.
Then there is the desire for the public to see that the shutdown is having an effect. Often the effects are real, but won't be visible for a long time in the form of delays or increased costs for long term projects. Shutting down websites reminds the public of just how serious this is. Organizations that appear to be functioning without funding may see their future funding reduced.
The meals and incidental expenses per-diem rates are significant, could easily be 25% of the total travel costs. Presumably those are saved if people don't go.
I think it is a bad precedent to let employees go if they pay for their own conference travel - it would provide a career disadvantage to employees who don't have enough personal wealth to pay for their own travels.
What is the part you think is wrong? This sort of thing is difficult to explain. The "correct' description in fairly recent physics is that gravity is due to the exchange of spin-2 gravitons. Maybe by now there are even more exotic explanations. They are way beyond me - and anyone else not in the field.
General relativity is a pretty good description - it matches all observations and experiments, the only (big) problem is that it is not compatible with quantum mechanics at very large energy scales. Quantum compatible descriptions of gravity lead to gravitons, and then the more exotic stuff that I don't understand at all.
General relativity describes the curvature of 4-dimensional space time. This is really difficult to visualize. Most visualizations (like the bowling ball on a rubber sheet) are showing just the curvature of a 2 dimensional spatial object into 3 spatial dimensions. Clever people who see this are confused because it doesn't seem to make sense - and they are right. Its a bad model. Other than the Kip Thorne ants on an orange model I gave above, (which isn't great either), I haven't seen a good intuitive model of curved space time.
Meanwhile many of the posters are not physicists. So I try to come up with an explanation that doesn't involved curved space time but which at least gives a vague idea of what is going on. Of course it is wrong. General relativity is wrong . Gravitons are wrong - we don't have a working theory of quantum gravity yet. All we have are models that fit experiments under some conditions.
Remember that all this thread was started by someone asking how gravity could affect "massless" photons. Its a good question. Since then it has evolved into a discussion of black holes and as the discussion gets more detailed, a better description is needed.
Are you so sure what your nephew says is wrong?
If you didn't post as AC I could at least see which of the objections were from you and which were from other people. I can't tell if you are just complaining or are contributing since there could easily be more than one AC on this thread. Why not use your real name like I do?
Photons could have a tiny rest-mass. You can't distinguish experimentally between a particle with a tiny mass moving very near the speed of light and a massless particle moving at the speed of light (this was part of my point in talking about the limit as the rest-mass gets small). People have put limits on this though and if the photon has rest mass it is TINY. Really really tiny.(I see a paper showing 1e-54 kg).
Your neutrino comment is a good example - it was thought to be mass-less, and to move at the speed of light, but later experiments showed that it had a small rest mass (still huge compared to the limit for the photon) and that it therefore must move slightly slower than the speed of light.
You can still have black holes even if photons have rest mass. Gravity would work essentially the same way. Enough matter in a small enough space would bend space so that all time like curves could not escape. Or put classically the gravity would be so strong that no object could escape -incluing the almost-speed-of-light massive photons.
Yes gravity is very weak, but it is unique among the forces in that there are no "negative" gravity charges and that like-charges attract. The electrical forces between 2 electrons are enormously stronger than the gravitational forces. If I try to collect a lot of electrons in one place though, those forces will push them apart.
If I take neutral particles (say atoms), the gravitational force of each one is incredibly tiny - but it is attractive. If I get a LOT (like the mass of a planet together), they will attract each other and their gravity will add and become stronger than any of the other forces.
You are right that a real black hole is likely anything but black - it is probably surrounded by clouds of relativistic hot gas - and "black holes" are likely the engines at the center of the brightest objects in the universe .
The standard image in popular science of a bowling ball distorting a rubber sheet isn't very good at conveying what is going on. It is not space, but rather space-time that is curved - you need to imagine the curvature of 4-dimensional space time - which normal humans like me can't do.
Kip Thorne had an example that was easier to think about. Imagine an orange with 2 ants at the equator. In this model space is 1 dimension, east / west. Time is latitude. So if the ants are not "moving" in space, they will walk northward as they go forward in time. After a while as they near the north pole the will find themselves closer together than when the started. Some "force" has drawn them together.
If we extend this: when an ant moves it walks east or west, but since it can't move faster than "light" in this model, it is still mostly moving north. If at all points it can only go a small angle away from north, no matter what it does it will end up at the "singularity" at the north pole of the orange.
I was taking a photon as the limit of a missive particle where you increase the velocity and decrease the mass in such a way that the mass-energy remains constant.
And I am NOT colossal, and my sexuality is not a matter of public record.
Otherwise though you are correct, but I was trying for an explanation that a non-scientist could understand.
A photon has mass energy. If I take an empty box made of perfect reflectors and add a photon, it will weigh more (by a tiny bit). It will have more inertia since inertial and gravitational mass are as far as we can tell exactly equivalent (as required if you use a curved space model of gravity).
In any case, words are a bit fuzzy. A photon has 4-momentum and the mass like term (or time like term if you wish) is non-zero.
btw- curved spacetime is a perfect model for all existing measurements involving gravity, but is incompatible with quantum mechanics at very (unreachable) high energies.
Yes, all timelike curves cross the event horizon and hit the singularity (I think, maybe not for rotating black holes) because of the curvature of space.
I wanted physicists to cover their ears because I was trying for a vaguely correct explanation that didn't require too much background.
Even without general relativity you could imagine a concentration of mass what would prevent (newtonian) light from escaping.
Physicists - please cover your ears, I'm trying to simplify.
When particle move near the speed of light their mass increases. At the speed of light it becomes infinite. Imagine a very light particle, moving very fast. By making it move near C I can get any mass I want. So now imagine i make the original particle lighter, an keep moving it faster in such a way that its moving mass stays the same. In the limit a particle with zero mass moving at the speed of light can have some moving mass. That is how a photon works.
Gravity will bend light, but the effect is very weak because light is moving very quickly. Gravity around a black hole is so strong that it will stop even light.
Real relativity and general relativity changes this a little, but the basic idea is the same. Photons are very light -> massless. They move very fast -> speed of light, so they have mass from their motion. Gravity doesn't bend light much - but black holes have very strong gravity so they do bend light.
The question of how to value a human life is very difficult. Clearly the population isn't worth quadrillions since there isn't that much wealth in the world. On the other hand we can't issue human hunting licenses to wealthy people at $100K / kill.
Depends on whether the causes of failure are independent. For example the probability of all 3 engines failing on an L1011 airliner would seem to be very small because they seem to be completely independent systems. I remember one case though of a cargo L1011 with a double, almost triple (last engine was dying) failure because a mechanic made the same mistake when he overhauled all 3 engines.
We would need real details ( I assume still classified) about the design of this system. If some common problem failed 3 of the switches, but the 4th was not susceptible to that sort of common failure, then it might not have been as bad as it sounds (though still very bad!).
On the other hand one problem with classified projects is that independent review is difficult. There may not be enough outside experts who are cleared to know the real technical details of nuclear bomb design.
With well over 10,000 warheads for over 20 years, I think the number of accidental detonations was zero. Remember that this was a ~5 trillion $ effort,With a typical government estimate of the value of human life at $10M, that is the equivalent of 500,000 lives so even an accidental detonation (outside of a major city) would not have dramatically increased the cost of the cold war to society.
Like many policy / technology discussions this one is a bit backwards. Without an idea of long term human goals, deciding on means is irrational. Its like arguing which direction to turn at the next corner before you have decided where you are going.
Is the goal human colonization of space? Then it probably makes sense to get as much experience as is practical with humans in space early in the process. Technology often doesn't improve if there isn't a direct push / requirement. (look at our space launch technology over the last 40 years). Human colonization of space is is a huge, difficult and expensive proposition - needs to be a major push of the civilization, not just something we do on the side.
Is the goal learning about space science? Then automation is probably the best approach now, and will be even better in the future. This of course begs the (very important) question as to the function of humans once automation is able to to EVERYTHING better. We end up as pets.... or vermin.
Is the goal human happiness? If by that you mean average happiness, then space isn't worth it - just adjust for a happy group of 100 million or so humans on earth. If you mean total happiness, then space can (in the very long term) support vastly more of those happy humans than Earth can.
Sadly as a civilization we are really terrible at deciding on long term goals. We use fuzzy words like "happiness" or "equality" or "freedom" or "greatness" without realizing how differently they can be interpreted by different people.
For me - space colonization is the top goal. If we are the only intelligence in the universe it would be a terrible shame if no intelligent creature ever saw all those wonders. If there are other intelligences out there - history shows that when the "guys on the boats" meet the "guys on the shore" , its a LOT better to be the guys on the boats.
Slashdot Mirror
But as a scientist you do need to trust. You can't do everything from scratch and need to make use of previous results. If you are doing an experiment with X-rays, you may need to trust someone else's instrument on the spectrum of the X-rays that are hitting your sample. You may not have prepared the sample yourself but need to trust whoever did to have done so correctly. You may rely on someone else's detectors to see the results of the experiment.
To some extent you can cross check the most difficult / risky parts of the experiment, but you can't cross-check everything withing a reasonable time and money budget.
We use matlab extensively at SLAC. If the license fee isn't a problem, it is a very powerful language for numerical work. The language includes a variety of high performance toolkits with multi-processor, distributed computing and GPU support.
OCTAVE and the other free versions really do not substitute for matlab - I'd recommend python instead if matlab is too expensive.
I've used python as well, and it is OK, but IMHO less optimized in structure for numerical work (even with pylab etc) than matlab, but better for other types of programming.
Because if they weren't paid, some of them would become unhappy and find other work. The cost of replacing those people could easily exceed the cost of paying for the furlough. I'm fortunate to work for a contractor (SLAC) so I wasn't furloughed, though it would have happened if the shutdown had gone on much longer. If I had been furloughed and didn't get back pay I might have been annoyed enough to see what other options are out there. I could certainly be replaced but I expect that the disruption to ongoing projects would make it more expensive that just paying me for that time.
Other organization are free to do as they want. I wonder if local coffee shops laid off workers because of reduced short term demand? I suspect that most would have kept them on to avoid the cost / risk of hiring someone new.
I think that electric vs. hybrid depends on your use pattern. If your typical use is a commute that is within the vehicle range, and you either rarely take long trips, or you have a second car, then pure electric may make sense. If you frequently need to drive beyond the recharge range of a pure electric, then a hybrid makes sense.
In my case the 30 mile range would work out OK. That would let me do my daily commute all on electric, but I would have the gas engine for long trips.
I don't personally want the sort of car the Cadillac builds, but I can see the appeal to some people. If most of your driving is 20mph in rush-hour traffic, a high performance sedan may provide no benefit at all, but soft seats, good sound system etc may make things more pleasant if you can afford them.
Whether pure-electric or hybrid is a win on CO2 likely depends on the energy mix in the area where you are charging the car. It also depends on how you measure: average energy mix or marginal energy mix? Then there are of course energy costs for the fabrication of the car, batteries etc. Overall though both approaches are quite good. The only influence I'd like to see the government apply to this is through taxes on energy sources, not specific taxes ore rebates on specific technology choices.
Its a synchrotron light source. Compare with pictures of APS, SPring8 and ESRF.
Many (all?) of the labs are contracted by the the government through other organizations. For example SLAC where I work is administered by Stanford University under contract with the Department of Energy. We are not shut down yet, but presumably will be soon if the government shutdown continues. We are under various restrictions to only do critical work, so, for example, the SLAC Today publication that reports on our work is not operating.
The lack of neutrons in this reactions is nice, but the protons and boron nuclei still need to overcome the Coulombe barrier. Generating practical fusion power still needs a combination of pressure, temperatures and containment times that have not yet been achieved in fusion machines. Accelerator base fusion works (for p-B, or hydrogen, but too many of the particles scatter rather than reacting so you can't reach break even.
This scheme sounds nice for R&D, but not at all clear that it can lead to break-even
Companies want to sell their products at the highest price each consumer will pay. By charging large fees for convenience items they are able to extract more money from people who place a higher value on their own time.
So, you could save money getting a SIM card for your phone to use internationally, but that would take time and make it more difficult for people to contact you. You could go to the hotel lobby for internet, but using the internet in your hotel room saves time.
This has the perverse effect that it may make sense for companies to spend extra money to waste your time or to provide worse service, if it pushes you to one of their higher priced services - assuming of course that they don't push you to a competitor.
Its just one of the very annoying effects of the free market. If you want to feel good about it, think if it as a "tax" on the wealthy who are able to put a higher value on their own time.
Thank you for writing this!
I've personally observed a standard digital camera interfere with the navigation radio on my Bonanza, and I've seen a flawed TURNED OFF emergency locator beacon interfere with GPS (the antenna was receiving a signal from a communication radio and the output diodes up-converted the signal into the GPS band and then this interference was re-transmitted.
I'm glad they are reducing the restrictions, but it was definitely worth studying carefully before they did so. It is NOT obvious that there is not a problem.
Were all the expenses already paid for? I've gone to a couple of conferences a year for the past 20 years and I've never been to one where there were not significant expenses that were charged at the time of the conference and reimbursed later. I'm in physics so maybe things are run very differently.
I think two things are going on:
There is a real desire to save money in every way possible to delay when more people need to be furloughed. Relatively small expenses add up.
Then there is the desire for the public to see that the shutdown is having an effect. Often the effects are real, but won't be visible for a long time in the form of delays or increased costs for long term projects. Shutting down websites reminds the public of just how serious this is. Organizations that appear to be functioning without funding may see their future funding reduced.
The meals and incidental expenses per-diem rates are significant, could easily be 25% of the total travel costs. Presumably those are saved if people don't go.
I think it is a bad precedent to let employees go if they pay for their own conference travel - it would provide a career disadvantage to employees who don't have enough personal wealth to pay for their own travels.
What is the part you think is wrong? This sort of thing is difficult to explain. The "correct' description in fairly recent physics is that gravity is due to the exchange of spin-2 gravitons. Maybe by now there are even more exotic explanations. They are way beyond me - and anyone else not in the field.
General relativity is a pretty good description - it matches all observations and experiments, the only (big) problem is that it is not compatible with quantum mechanics at very large energy scales. Quantum compatible descriptions of gravity lead to gravitons, and then the more exotic stuff that I don't understand at all.
General relativity describes the curvature of 4-dimensional space time. This is really difficult to visualize. Most visualizations (like the bowling ball on a rubber sheet) are showing just the curvature of a 2 dimensional spatial object into 3 spatial dimensions. Clever people who see this are confused because it doesn't seem to make sense - and they are right. Its a bad model. Other than the Kip Thorne ants on an orange model I gave above, (which isn't great either), I haven't seen a good intuitive model of curved space time.
Meanwhile many of the posters are not physicists. So I try to come up with an explanation that doesn't involved curved space time but which at least gives a vague idea of what is going on. Of course it is wrong. General relativity is wrong . Gravitons are wrong - we don't have a working theory of quantum gravity yet. All we have are models that fit experiments under some conditions.
Remember that all this thread was started by someone asking how gravity could affect "massless" photons. Its a good question. Since then it has evolved into a discussion of black holes and as the discussion gets more detailed, a better description is needed.
Are you so sure what your nephew says is wrong?
If you didn't post as AC I could at least see which of the objections were from you and which were from other people. I can't tell if you are just complaining or are contributing since there could easily be more than one AC on this thread. Why not use your real name like I do?
Photons could have a tiny rest-mass. You can't distinguish experimentally between a particle with a tiny mass moving very near the speed of light and a massless particle moving at the speed of light (this was part of my point in talking about the limit as the rest-mass gets small). People have put limits on this though and if the photon has rest mass it is TINY. Really really tiny.(I see a paper showing 1e-54 kg).
Your neutrino comment is a good example - it was thought to be mass-less, and to move at the speed of light, but later experiments showed that it had a small rest mass (still huge compared to the limit for the photon) and that it therefore must move slightly slower than the speed of light.
You can still have black holes even if photons have rest mass. Gravity would work essentially the same way. Enough matter in a small enough space would bend space so that all time like curves could not escape. Or put classically the gravity would be so strong that no object could escape -incluing the almost-speed-of-light massive photons.
Yes gravity is very weak, but it is unique among the forces in that there are no "negative" gravity charges and that like-charges attract. The electrical forces between 2 electrons are enormously stronger than the gravitational forces. If I try to collect a lot of electrons in one place though, those forces will push them apart.
If I take neutral particles (say atoms), the gravitational force of each one is incredibly tiny - but it is attractive. If I get a LOT (like the mass of a planet together), they will attract each other and their gravity will add and become stronger than any of the other forces.
You are right that a real black hole is likely anything but black - it is probably surrounded by clouds of relativistic hot gas - and "black holes" are likely the engines at the center of the brightest objects in the universe .
The standard image in popular science of a bowling ball distorting a rubber sheet isn't very good at conveying what is going on. It is not space, but rather space-time that is curved - you need to imagine the curvature of 4-dimensional space time - which normal humans like me can't do.
Kip Thorne had an example that was easier to think about. Imagine an orange with 2 ants at the equator. In this model space is 1 dimension, east / west. Time is latitude. So if the ants are not "moving" in space, they will walk northward as they go forward in time. After a while as they near the north pole the will find themselves closer together than when the started. Some "force" has drawn them together.
If we extend this: when an ant moves it walks east or west, but since it can't move faster than "light" in this model, it is still mostly moving north. If at all points it can only go a small angle away from north, no matter what it does it will end up at the "singularity" at the north pole of the orange.
I was taking a photon as the limit of a missive particle where you increase the velocity and decrease the mass in such a way that the mass-energy remains constant.
And I am NOT colossal, and my sexuality is not a matter of public record.
Otherwise though you are correct, but I was trying for an explanation that a non-scientist could understand.
A photon has mass energy. If I take an empty box made of perfect reflectors and add a photon, it will weigh more (by a tiny bit). It will have more inertia since inertial and gravitational mass are as far as we can tell exactly equivalent (as required if you use a curved space model of gravity).
In any case, words are a bit fuzzy. A photon has 4-momentum and the mass like term (or time like term if you wish) is non-zero.
btw- curved spacetime is a perfect model for all existing measurements involving gravity, but is incompatible with quantum mechanics at very (unreachable) high energies.
Yes, all timelike curves cross the event horizon and hit the singularity (I think, maybe not for rotating black holes) because of the curvature of space.
I wanted physicists to cover their ears because I was trying for a vaguely correct explanation that didn't require too much background.
Even without general relativity you could imagine a concentration of mass what would prevent (newtonian) light from escaping.
Physicists - please cover your ears, I'm trying to simplify.
When particle move near the speed of light their mass increases. At the speed of light it becomes infinite. Imagine a very light particle, moving very fast. By making it move near C I can get any mass I want. So now imagine i make the original particle lighter, an keep moving it faster in such a way that its moving mass stays the same. In the limit a particle with zero mass moving at the speed of light can have some moving mass. That is how a photon works.
Gravity will bend light, but the effect is very weak because light is moving very quickly. Gravity around a black hole is so strong that it will stop even light.
Real relativity and general relativity changes this a little, but the basic idea is the same. Photons are very light -> massless. They move very fast -> speed of light, so they have mass from their motion. Gravity doesn't bend light much - but black holes have very strong gravity so they do bend light.
NOAA aviation weather tools are done in java - used extensively by pilots.
The question of how to value a human life is very difficult. Clearly the population isn't worth quadrillions since there isn't that much wealth in the world. On the other hand we can't issue human hunting licenses to wealthy people at $100K / kill.
Depends on whether the causes of failure are independent. For example the probability of all 3 engines failing on an L1011 airliner would seem to be very small because they seem to be completely independent systems. I remember one case though of a cargo L1011 with a double, almost triple (last engine was dying) failure because a mechanic made the same mistake when he overhauled all 3 engines.
We would need real details ( I assume still classified) about the design of this system. If some common problem failed 3 of the switches, but the 4th was not susceptible to that sort of common failure, then it might not have been as bad as it sounds (though still very bad!).
On the other hand one problem with classified projects is that independent review is difficult. There may not be enough outside experts who are cleared to know the real technical details of nuclear bomb design.
With well over 10,000 warheads for over 20 years, I think the number of accidental detonations was zero. Remember that this was a ~5 trillion $ effort,With a typical government estimate of the value of human life at $10M, that is the equivalent of 500,000 lives so even an accidental detonation (outside of a major city) would not have dramatically increased the cost of the cold war to society.
Completely agreed.
Also, a large part of the point of manned space is that it is difficult.
Like many policy / technology discussions this one is a bit backwards. Without an idea of long term human goals, deciding on means is irrational. Its like arguing which direction to turn at the next corner before you have decided where you are going.
Is the goal human colonization of space? Then it probably makes sense to get as much experience as is practical with humans in space early in the process. Technology often doesn't improve if there isn't a direct push / requirement. (look at our space launch technology over the last 40 years). Human colonization of space is is a huge, difficult and expensive proposition - needs to be a major push of the civilization, not just something we do on the side.
Is the goal learning about space science? Then automation is probably the best approach now, and will be even better in the future. This of course begs the (very important) question as to the function of humans once automation is able to to EVERYTHING better. We end up as pets .... or vermin.
Is the goal human happiness? If by that you mean average happiness, then space isn't worth it - just adjust for a happy group of 100 million or so humans on earth. If you mean total happiness, then space can (in the very long term) support vastly more of those happy humans than Earth can.
Sadly as a civilization we are really terrible at deciding on long term goals. We use fuzzy words like "happiness" or "equality" or "freedom" or "greatness" without realizing how differently they can be interpreted by different people.
For me - space colonization is the top goal. If we are the only intelligence in the universe it would be a terrible shame if no intelligent creature ever saw all those wonders. If there are other intelligences out there - history shows that when the "guys on the boats" meet the "guys on the shore" , its a LOT better to be the guys on the boats.