A Level Physics Revision: All of Cosmology | Parallax, parsecs, Doppler, CMBR, Hubble's Law

[@zhelyo_physics]

Hi guys! I have also filmed some past paper questions practice. Hopefully it is helpful! : ) kzbin.info/www/bejne/pKa3lZWPgZ2LZq8

[@zoyajalal6433]

You have no idea how helpful your videos are....I'm so grateful....your way of explaining and covering each and every point is Just Amazing. Thank you so much. I've got my CIE A2 Physics tomorrow.

[@mdarmanhossain2153]

I really feel like God sent you as an angel to help me with my exam 😭. Thank you so much!

[@zhelyo_physics]

No problem! Good luck revising!

[@Vigilant69]

I'm super glad that you exist, love your explanation dear sir!

[@zhelyo_physics]

Thank you! Glad this is useful! : )

[@kxaie]

Fantastic video, helped alot, only thing is at the end with the section about dark matter, that section replayed.

[@zhelyo_physics]

Glad you enjoyed it. Thanks for letting me know, will fix that 😀

[@DRMAOMMAIZEINNG]

awesome video, really helped for my upcoming exams, which is starting with paper 1. One thing to point out is that you seem to accidently repeat the dark matter section twice, not sure if this was intentional or not.

[@gjeraldh2989]

Thank you, it is helpful to revise after my lessons.

[@zhelyo_physics]

Glad it is helpful!

[@enurih3543]

Thank you for this video! This was incredibly helpful!

[@zhelyo_physics]

Great to hear! Thanks for the comment!

[@nonviablegerm71]

Absolute legend, thanks so much for the video!

[@zhelyo_physics]

anytime! thanks for the comment!

[@neuropcs5879]

Incredibly helpful! Thank you :)

[@zhelyo_physics]

Glad to hear so! Thanks for the comment!

[@gautammorkhandikar394]

do we need to know about the doppler effect or just the equation for doppler shift in OCR? Also are we expected to know red shift and blue shift?

[@zhelyo_physics]

the equation is given in the formula booklet, and you need to know how to use it, together with red shift/blue shift. Good luck revising!

[@gautammorkhandikar394]

@@zhelyo_physics thank you!

[@bigboyali2312]

quick question! If hubble's constant a... constant, and if the age of the universe is 1 divided by hubble's constant does that mean the age of the universe is constant? frozen in time? or is hubble's constant isnt really a constant and just changes with time? in that case what would a hubble's constant against time graph look like?

[@zhelyo_physics]

such a great question!! Hubble's constant is not actually a constant....in time : ) Actually it is a constant in space meaning that it is the same at every location in the universe (so far as we can tell), but it's value is actually changing with time. Hope this helps, great question!

[@nadiaaaj6618]

awesome. thank you so much. hope this helps me on on test next week

[@zhelyo_physics]

Glad to hear! Best of luck on the test!

[@Zecos]

wow studying the big bang has made my belief in religion stronger!!!! it sounds soo stupid and even science cant explain the universe!! tysm physics ilysm :)

[@ibaba-ez3om]

lmao frr

[@justinlash]

i]s ]this sequence of big bang ]] enough for full marks

[@zhelyo_physics]

always depends what the question is asking, they are rarely on memory, typically they would throw in some specific data or something similar to comment on the question

[@emmanuelige9889]

Hi sir, do you agree with this statement or am I incorrect. If the lab wavelength is shorter than the measured wavelength then the object is moving away (Redshift), and if the lab wavelength is longer than the measured wavelength, then the object is moving closer (Blueshift).

[@zhelyo_physics]

I agree

[@hectorpearson3390]

thank you for vid, gl ppl

[@zhelyo_physics]

Anytime! Good luck!

[@yana1067]

hi hi, a quick question that i kinda need clarifying, if we got asked a question on the big bang, would we need to know the time stamps? for example it was 380000 years after the big bang when the universe started to cool down, would the time have to be stated?

[@zhelyo_physics]

I am gonna go with no. The spec doesn't explicitly state that you need to know the times, but you need to know the sequence.

[@yana1067]

@@zhelyo_physics ohh okay thank you!

[@kausarlolz]

hi sir, do we need to know the time for the big bang processes? for ocr a

[@zhelyo_physics]

I’d revise it but not stress about it as paper 3 is typically more problem solving based. You never know though. Good luck tomorrow!

[@xodusgraphicdesigns3384]

Thanks for the video really good, i like how you don’t put in useless info. Can you do a specific big bang video because the ocr exam i have done requires more info on the Big Bang. E.g the universe is hot and dense…

[@zhelyo_physics]

excellent idea! thank you so much!

[@udayreddy3705]

hi sir i came across this formula where light years = 1AU/ 1 light year. Is this right ? And if so when is it really used?

[@zhelyo_physics]

never seen it before, it's not correct too I am pretty sure as the dimensions on the left (units of distance), don't equal the dimensions on the right. Where did you come across it?

[@mikhaelhalbar417]

Amazing video thank you so much

[@zhelyo_physics]

Glad you enjoyed it!

[@Allinone-nm2jh]

thank you very much sir .

[@zhelyo_physics]

anytime! thank you for the comment!

[@SorabeeZ]

do you need to know ab olbers paradox, open,closed,flat universe and their graphs and critial density for OCR A? ive seen it come up in topic questions but its not something we learnt in school.

[@zhelyo_physics]

Hi, they are not, they used to be on the OCR spec before 2017, however not anymore.

[@videoharry_]

6:03 does Δλ/λ = -v/c rather than just v/c as you’ve put. In your “all of astrophysics” you put the former equation but in this you have the latter. I assume the former is correct?

[@zhelyo_physics]

So the two exam boards have chosen slightly different variations of the same equation.

[@jameshosking8541]

Do I need to know the exact value of an astronomical unit?

[@withtheflow8528]

If you're on the OCR A exam board it is in the formulae booklet

[@Crimseno]

@@withtheflow8528 U got to remember the exact value for the astronomical unit for OCR A, its 1.5 x 10^11m. Idk bout the other exam boards.

[@supersloths7052]

Is this video for the AQA specification?

[@zhelyo_physics]

Nope - I have filmed the whole of AQA astrophysics here: kzbin.info/www/bejne/a52aaWqoqZyWr5Ysi=JsDOQS0-wAuwRLQM Enjoy!

[@barnaby4232]

Does the AU value need to be remebered and do we not need to know the fate of the universe?

[@zhelyo_physics]

Hi, which spec are you doing? For OCR I would remember the astronomical unit, the fate of the universe is no longer on the OCR spec though. If you are doing a different exam board it might be different

[@barnaby4232]

@@zhelyo_physics yes I am doing OCR I assumed it was on the spec as it’s in the textbook, maybe it’s out of date

[@naturemc2]

thanks!

[@zhelyo_physics]

Anytime!

[@naturemc2]

@@zhelyo_physics if you add some historical information about how we get the hubble law and why parsec is useful and important. It would be great

[@zhelyo_physics]

I agree! Thanks for the idea!

[@jefferylarry-w5w]

do we need to know the mnames of the guys who invetend the background radiation theory.

[@zhelyo_physics]

nope!

[@jamiebarnes4804]

awsome video really helped me a lot in understanding parsecs but just as a side note i think you forgot to convert nm to meters for the doppler shift or i could be completely wrong

[@zhelyo_physics]

Hi, thanks! So with the Doppler Shift, because you are using change in wavelength/wavelength the units will cancel so no need to convert in a fraction. Hope this helps!

[@jamiebarnes4804]

@@zhelyo_physics ohhhhh I see cheers