GR100

All over the world people are celebrating 100 years of General Relativity (yes! Einstein proposed the theory 100 years ago and we have been using its applications ever since!) and Imperial was one of them. This Monday Imperial College held a lecture to celebrate this huge milestone. PhD students of Professor Hawking were speakers at the event and Stephen Hawking himself was meant to be there but unfortunately fell ill and was unable to come. Nonetheless, the talk went on with Hawking there in spirit.

Following on from this Imperial College wanted to find out what we (the public) thought would happen if we were sucked into a black hole. A cute Einstein badge was up for grabs and I just had to submit my thoughts so I could get one!

Here is my answer to the question which was, of course, aided with the knowledge I have gained so far in my physics degree at Imperial. Enjoy!

Before we answer the question what would happen if you were sucked into a black hole, let’s begin with the question what is a black hole?

Einstein has taught us that gravity can be considered as warped space-time. The denser an object the more warped space time is around the object. A black hole is an extreme case of warped space time - so extreme, that at the most warped part it is a singularity! A black hole is produced by an extremely heavy star that has run out of fuel and collapsed in on itself. 

A good analogy of this is if you consider a bowling ball on your mattress - the mattress would sink inwards and near the bowling bowl you would see more sinking. Now, imagine that the bowling ball didn’t change in size but changed in density and became really, really, REALLY dense, then, you’d see a lot of sinking in! if you had a marble it would sink straight into the hole but physics inside a black hole or near it is a little strange…

At the outer boundary of a black hole is the EVENT HORIZON - if you pass this point there is NO RETURN. The event horizon is full of streams of hot particles that radiate back into the Universe due to quantum effects, this radiation bears the name of it’s discoverer: Hawking radiation. Additionally, at this point the gravitational force precisely counteracts the light’s effort to escape the black hole.

So, now go back to the question of what will happen if you were to get sucked by a black hole?

Let’s consider a friend watching you far from the black hole - she/he sees you get ‘spaghettified’. The gravitational field strength at your feet is stronger than that at your head so you get stretched! You also appear to move in slow motion the closer you get to the event horizon. At the event horizon, your friend sees you ‘frozen in time’ and you stay there motionless and stretched until you get reduced to ash because of the Hawking radiation.

But what about if we consider it from your point of view what would happen? Nothing.. just nothing. No spaghettification (except if the black hole were small). This is because you are in free fall and so feel no gravity. You cannot escape the black hole as this would involve travelling backwards in time but time only goes forwards. 

All in all, getting sucked in by black hole is more entertaining for your friend that it is for you.

Within minutes after posting it on Twitter I received a tweet from @imperialspark informing me of my winnings! I was so happy - cannot wait to receive my badge (selfies will be posted here in due course). 

Why not send your thoughts on Twitter (@ImperialCollege) or Facebook (Imperial College London) and win a badge too!

Popomatic safety sign complete!

After a long day of undergrad lab (Compton effect experiment where each reading takes half an hour!) I decided to take a break and start designing the safety sign for the popomatics (balloon-popping laser) I am building. I wanted to not defer too much from the original sign but add a modern twist to it.

The safety sign must include:

• Wavelength of the laser (532 nm - green laser)

• Type of laser (in this case CW which means Continuous Wave - basically, it has a continuous output and is not pulsed)

• Power of the laser (100 mW)

• Class of the laser (here, it is Class 3B which means you cannot look at the beam directly as it is hazardous to the eye but if you look at diffuse reflections for instance reflections from matte surfaces, preferably dark matte surfaces are not harmful - hence the need for the 'safety screens' I mentioned in the previous post here).

And also some safety statements about the permitted users and informing the user to not stare directly at the beam.

Here is the previous sign:

Original safety sign.

And here is the new one!

New laser safety sign for the popomatic!

Popomatic update!

This week I've been busy sticking the 'safety screens' onto the lids of the popomatic (balloon popping laser). 

My orders, consisting of a clear silicone sealant and vulcanised fibre washers, arrived earlier this week and I could get to work on sticking the optical hardboards ('safety screens') onto the lids! (Half of the lids are still being delivered so I couldn't stick on half of the 'safety screens'). It was great to be back in the lab and to meet all the cool PhD students and postdocs again!

Here are a few videos and pictures of me sanding down the optical hardboards and applying the glue onto the pieces and sticking them on the lids! It's nice to see the popomatic slowly take shape!

Vulcanised fibre washers

Silicone sealant

The optical hardboards were glued onto the lids!

The finished lid put onto the popomatic! But I will need to add a safety sign onto this, which will cover the glue.

#PhysicsBanter

One of the most inspirational postdocs left on Friday and it was a little bit emotional. She had helped me so much in my first summer placement with the Plasma Group and she acted as my first ever female role model at Imperial College. She was the only female in the Plasma Group and I was totally inspired by her seamless knowledge, ability to work in such a male-dominated group and how she offered to help everyone that needed it. She is now going to work at SLAC and I am so happy for her! She is an amazing laser specialist and SLAC will certainly benefit from her presence! It's sad to see her go but she will be loved just as much at SLAC as we did at Imperial!

Here are a few images highlighting the stuff we did for her leaving do - it included some very tasty cake!

The AMAZING gift the Plasma Group gave her - a ruby rod used in laser experiments and she's a laser specialist - so right up her street!

Leaving lunch!

This was SCRUMPTIOUS!

Mmmmm....

The lovely Plasma Group! <3 

#PhysicsBanter

Laser thermometer #EndlessFun

An 'optical crowd'

Where gas jet experiments happen!

More updates on the popomatic!

Last week I received the optical hardboards (basically just really dense polystyrene sandwiched by card) which shall protect our eyes from the laser beam and shall be placed on both the top and bottom lids of the popomatics! The laser used shall be a class 3b laser that is hazardous for the eyes, thus, we must implement some safety measures.

I must admit, I did crack a few of the pieces of optical hardboard whilst I was cutting out the first pieces! Whoops - but I got there in the end! :)

In the following images you'll see me draw and cut out the pieces I need from the optical hardboard. A future blog post shall hopefully see me stick the pieces onto the lids!

Colouring pencils! Feels like I'm doing art coursework for school! ;)

Referring to my lab book for dimensions - that's why we need lab books!

The places where I needed to cut were drawn out...

...and cut out.

The left overs look a bit artistic!

The finished 'safety screens' and all the equipment I used - 'all in a day's work!' ;)