Nothing more than a dull light of the computer screens illuminated the gloomy study belonging to Mr Pietraszko, MSc. Nothing happened for a long time. How long? None of them was aware of the passage of time. An hour, maybe more. They waited in silence. Yet none of them knew what they were waiting for. Pietraszko checked the communicates on the displays every few minutes trying to catch some clue, some hint as to what had happened and what to do to make that story end happily. Professor Błaszczyk had never felt so helpless before. He didn’t know how to help the teenagers. He had to rely on Mr. Pietraszko, MSc, who was surreptitiously derided by the student and openly laughed at by many fellow scientists, and on his scientific ideas balancing on the verge of sanity. Even if Pietraszko’s theories about the nature of time and events were correct, he didn’t care for it at all at that moment. He was focused on Beata and Artur.
- Something is going on – Pietraszko burst on his thought. –Markov chains no longer converge, there is no ergodicity. It looks as if the algorithm comes to some serious obstacle. In fact it’s logical –Pietraszko was talking to himself. – But they cannot jump ahead, into the future, further than 2015. Oh, well, now I see, they’re going to return to the stationary distribution – Mr. Pietraszko, MSc was very glad.
- Beata! Artur! Finally –professor Błaszczyk cried with relief seeing two people emerging behind the console located in the dark corner of the studio.
Pietraszko stopped his calculations.
- You caused a pretty mess – he said raising his eyes from the keyboard. He faced the teenagers, crossed his arms and waited. This was not a particularly warm welcome and it didn’t bode well. Bit thought that he actually preferred 19th-century tenements to this. Nothing could be worse than gloomy bearded face of unpredictable Mr. Pietraszko, MSc.
- We... - Bit said uncertainly– … didn’t want. That is... we only wanted to check where was the room we found on the map.
You found – Beta thought but she decided not to open her mouth. She let Bit explain himself.
- What map? –Pietraszko hissed and the teenagers understood that things were really bad. – Did you rummage through my private folders on my private account?
Pietraszko was turning intensively red and professor Błaszczyk could not believe what he had just heard. He knew that Bit liked to break security measures and that his satisfaction from cracking was greater than his fear of potential consequences. He knew how that felt himself. Yet he believed that Artur was wise enough not to hack the data at his father’s work. And if not Artur, then certainly Beta, who usually brought her brother down to earth.
- You broke into my own account, then to my study and then you stole my invention… – he hissed.
- Stole? – Bit was surprised.
- Yes, you stole it –Pietraszko confirmed with diabolical satisfaction. – And yes, give it back to me.
- No... I only touched it. I wanted to check and I accidentally pressed .. – Bit tried to explain incoherently as he put the invention on the console.
- So you wanted or you pressed it by chance? – Pietraszko insisted.
- You let us into your study yourself –Bit retorted.
- Let’s finish this –professor Błaszczyk cut in suddenly. – My dear friend – he turned to Mr. Pietraszko, MSc – please tell them what you expect from them.
- I’ll be honest –Pietraszko begun- and I don’t think you’ll be surprised by what I’m going to say: these kids always got on my nerves. And it’s not going to change. But I promise to forget about everything if they tell how on earth they managed to return to our times– the scientist shifted his focus from the break-in to something much more interesting to him. – The driver is not finished and it contains errors. How did you know how to calibrate it?
- Well, we had some problems with it too– Bit admitted. – Mr. Jan helped us.
- What Mr. Jan? - professor Błaszczyk asked.
- Linear regression– Beta decided that it was a good moment to join the conversation and boast of her knowledge at the same time.
- We gathered data describing the working of the watch and then we calculated the year that should be entered –Bit cut in confidently as if discovering workings of time vehicles was his everyday occupation.
- Linear regression –Pietraszko repeated with surprise. – Such a banal solution that it seems almost impossible – she said. Where did you get the data to determine it?
- We travelled in time a little –Bit answered, evidently pleased with himself.
- Even during our first travel we were thrown into a different year than we had chosen - Beta explained. – We should’ve got into 1876 but we were thrown into 1885. We didn’t care for it then. But later we entered 2015 and we got into 1945. It seemed obvious then that the machine makes errors. And in the meantime we were twice thrown into some other years for short moments.
- It must’ve happened when I was trying to find out where you were – Pietraszko observed.
- I decided than we should jump in time once more to check what was really wrong with your invention – Bit joined the story. – I entered 2098 and we got into 1981.
- How did you know what was the current year? The machines gives wrong dates – Mr. Pietraszko, MSc wanted to know every detail.
- Actually, we had a guess only once, with 1945 – Bit related. –We used a newspaper the first time –we read the year of publication –and the second time we were helped by Mr. Jan.
-You talk about that Mr. Jan again. Who’s he? - professor Błaszczyk could not wait.
- Mr. Jan protected us from the soldiers… - Bit didn’t finish.
- And helped us to solve that puzzle – Beta didn’t want her brother to rob her of the whole story. – We had four points in time: three from our jump –we knew then what was entered in the watch and what year we got into, and one point which we wanted to reach. We only needed to know what year we should enter to get back to 2015. Mr. Jan told us then about the linear regression.
- How is it possible to travel in time anyway? – professor Błaszczyk was starting to think logically again.
- It isn’t possible and I will not tell you the secret, no way –Pietraszko promised. – It’s enough for you to know that I based my calculations on the law which all of you derided. And now what? You ask me how is that possible and I’m supposed to tell you everything? None of you’ll understand or appreciate it. But the linear regression... – Mr. Pietraszko, MSc changed his tone and his face became somber. – The type of error which could not be discovered in the study. I’d have to travel in time myself to find it out – he said bitterly. He lacked the courage to do something so crazy. He’d decided it was too dangerous. And now these kids robbed him of all satisfaction. The joy he initially felt evaporated. Now he felt only regret and anger. – You’re still here? – he asked sharply after a moment. – Het out of here, I need to clean up! – he started to shout.
- So? Shall we go for these mathematical problems? And then for dinner? - professor Błaszczyk asked the teenagers. He pretended that he hadn’t heard Pietraszko’s rude question. Beta and Bit only nodded their heads; it was better to say nothing.
Beta and Bit shouted over one another relating their adventures to Jacek. They didn’t mind that they were walking along the university’s hall.
- … and that man, he was called Głowacki –Bit said.
- He protected us against some other man who was speaking Russian, I think. He said that that Głowacki was from the newspaper –Beta added.
- Where the Filters are located. Only they were under construction then. I recognized them thanks to the tower.
- Wait, you saw the construction of the filters? Głowacki? From the newspaper? - professor Błaszczyk started to laugh. – It seems that you met Bolesław Prus.
- No, Bolesław Prus signed an article in the newspaper in which we found the date –Bit explained.
Jacek quickly took out his mobile phone and started to look for something. – Did your Głowacki look like that? – he showed them a picture of a man in round glasses and sharp beard.
- Głowacki... Of course! Aleksander Głowacki was Bolesław Prus! – Beta cried.
- I think that both of you must buckle down to Polish classes–Jacek joked. – Talking about classes, I just remembered something. I left my students’ courseworks in Mr. Pietraszko’s study.
- Don’t tell me we need to go back to his cavern –Beta made a wry face. She didn’t feel like meeting the eccentric scientist again.
- I’ll go –Bit offered happily. He was afraid of unpredictable Pietraszko but his curiosity exceeded his fear.
The door to the study was still open. It means that Mr. Pietraszko, MSc hadn’t left the university yet. Professor Błaszczyk knocked but nobody answered. He entered the room. Pietraszko wasn’t inside so the professor didn’t hesitate to open the hatch under the window and step inside. The children followed him.
- My dear friend – he cried as was going downstairs.
Nothing’d changed. The computers were still working. – Haven’t I left here my students courseworks? – he asked and looked around. – Mr. Pietraszko – he cried again.
- He set off for a time travel –Bit joked.
Professor Błaszczyk went to the console. His students’ courseworks were lying there untouched. He took them and headed for the stairs when something stopped him. Not only Mr. Pietraszko, MSc was gone. The device that Bit put on the console was gone as well. Instead they saw a sheet of paper with hastily scrawled dates given by Beta and Bit. One date from a shortened version of a system of equations was circled.
- 1975 – professor read out loud.