Klaynos

If you have a very good dual frequency GPS receiver you can extract column water vapour content.

A good question. The answer is basically that we don't know. The big bang is a model of the expansion of the universe from a very short time after t=0 until now. We don't know what happened before that but it looks like either the energy has always existed or the time symmetry was broken.

! Moderator Note All, please try and keep this thread civil. It's for talking about the bits of info.

The best advice is likely to be to study what we already know, which include the mathematics if it. You might not like to hear that but the only way you're going to be able to explain this to a physicist is talking our language, that's maths. It takes people around 10 years of full time study to get the basis to start making contribution without significant help from others. The experts have been studying this for 40 years and still don't have the answer you claim. This really isn't a shirt road you're heading down but it's an incredibly interesting one.

People are human, the fact one of them once got something wrong shouldn't be terribly surprising and why science doesn't care who said what only how good the models are (how well they compare to measurements).

No. If someone came along with a mathematical theory as robust as our current theory but more accurately agreed with the observations (taking error analysis into account) then we would start using the new theory. What you have to bear in mind is that BBT and general relativity are incredibly accurate in the domains of applicability. So a simple first test as to whether a new theory is valid is whether it gives the same numerical predictions as them. Interestingly this can be done for general relativity. Where Newtonian gravity works GR must produce the same result else we'd have known quickly that it was not going to work.

I completely agree. I shan't be moving my systems from GPS to another GNSS any time soon.

The last thing I read suggested that there will be significant interoperability with GPS and Galileo.

Immersat is not a positioning network. The clocks on the satellites need to have corrections applied. These include special and general relativistic corrections and will vary with orbit. There's a few GNSS networks, glonass, Galileo, GPS and beidou all exist to a certain extent. They're all in similar altitude orbits and not geostationary. Your local antenna is where I'd start fault finding. If this is really safety critical you should use more than one network.

Thank you. Very interesting stuff.

They eye is a nonlinear detector with some crazy image processing. It's a very different problem doing this in a dark tunnel compared to a moonlit night.

Yep. Depends what it's for and whether it needs to integrate with anything else. If it was me and manual control I'd use a torch.

There are several things you can do or you need to think about. - The brightness you'll be able to see will depend on the ambient light. It'll need to be much brighter if you're near a city than miles from anywhere on a moonless night. - if you want to use a traditional spherical point source bulb then your best bet is an integrating sphere and some optics. The sphere gathers the light and puts it out a single output and you can then try and use optics to collimate the light. This won't be cheap, the collimation will be limited and it'll suffer from alignment changes. - use a directional light source. You can get directional LEDs or go all the way and get a laser diode, a relatively low power one that is eye safe should be your stating point. They're pretty cheap but might mean you need to build some electronics to power it. The beam will spread out but you'll need to work out how much to see whether it'll need to be very accurately lined up. - a decent torch, they often have optics to do some limited collimaton. It's all but and ready to go... Again you might need to build some electronics to power from the solar panel.

We're not reopening that thread here.

You failed to address the points raised by Mordred. If you have a problem with the moderation action you may report a post and have it reviewed by other moderators.

The rules are clearly laid out.

! Moderator Note and this is why I'm closing it. JohnLesser, please try to learn some science if you want to contribute here but do not reintroduce this topic.

I've not used a teensy yet. They do look really interesting. EKF seems like a very sensible approach to handing the noisy data, what frequency do you measure at?

Sorry, I meant op, i assumed you'd found links of interesting things. I've seen people build sit on segway type devices that use similar systems. Mostly built around different arduinos. The rover I'm planning is more of a terrain traverser than these are likely to be. I want something that can get to the end of my garden and back. It's not far but there are steps in the way... The idea being that if it can do that then it'll be capable of crossing a grass field.

What microcontroller are you using?

This is why we use mathematical models. You can then predict numerically what you expect to see from your telescope. If that's not what you see you know you model is incomplete/wrong (depending on the circumstances). This is exactly what happened to discover dark matter. We looked into the skies with our telescopes and what we saw doesn't match what we model so our model is missing something. The placeholder name for that something is dark matter. Thus far any attempt to add something we know about other than non-elecromagnetic interacting mass into the models doesn't work.

The UK increased the age at which you could buy tobacco, from 16 (age of concent) to 18 (age you can buy alcohol). This has lead to a drop in young people smoking. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3158837/ Whilst I see the argument for removing the age as it's something you can do when you turn a certain age I think that's a bad idea for a few reasons. You would have a big increase in the short term when it's legalised as suddenly it's legal for 14 year olds to buy tobbaco, starting earlier is even worse for you than starting later in life, and it's addictive so kids are likely to try it a few times (they will make more foolish decisions than older people on average) and then be stuck.

People will also have their own conventions. I was not the first person to publish in the same field as my first publication with my first and sur names. I therefore used my middle initial as well, to keep consistent this is what I continue to do in my current field. Check out your supervisors publications to see how they are normally presented. That might not work for clinitions as they may not have published. You can always ask them.

That's why i assumed I couldn't find anything. Walking to work everyday I'm becoming more generally worried about pollution. This is wandering slightly off topic, sorry.

I'm opposed to smoking around me but this was also my thought yesterday. I briefly tried to find any papers on the relative dangers of passive smoking and general pollution but I only found news paper reports quoting who representatives and similar.